CA2134745A1 - Glycosaminoglycan-synthetic polymer conjugates - Google Patents

Abstract

GLYCOSAMINOGLYCAN-SYNTHETIC POLYMER CONJUGATES

Abstract of the Disclosure Pharmaceutically acceptable, nonimmunogenic compositions are formed by covalently binding glycosaminoglycans or derivatives thereof, to hydrophilic synthetic polymers via specific types of chemical bonds to provide biocompatible conjugates. Useful glycosaminoglycans include hyaluronic acid, the chondroitin sulfates, keratan sulfate, chitin and heparin, each of which is chemically derivatized to react with a hydrophilic synthetic polymer. The conjugate comprising a glycosaminoglycan covalently bound to a hydrophilic synthetic polymer may be further bound to collagen to form a three component conjugate having different properties. The hydrophilic synthetic polymer may be polyethylene glycol and derivatives thereof having an average molecular weight over a range of from about 100 to about 100,000. The compositions may include other components such as fluid, pharmaceutically acceptable carriers to form injectable formulations, and/or biologically active proteins such as growth factors or cytokines. The conjugates of the invention generally contain large amounts of water when formed. The conjugates can be dehydrated to form a relatively solid implant for use in hard tissue augmentation. The dehydrated, solid implant can further be ground into particles which can be suspended in a non-aqueous fluid and injected into a living being (preferably human) for soft tissue augmentation. Once in place, the solid implants or particles rehydrate and expand in size approximately three- to five-fold.

Description

~13;~7~5 GLYCQ~M~QC~I,YCA~-SYNTH~C POI~lvlER CONJUGATES

2 Cross-Referenees 3 This application is a continuation-in-part of copending U.S. application Serial 4 No. 07/907,518, filed July 2, 1992, which is a continuation-in-part of U.S. Patent No. 5,162,430, issued November 10, 1992, which is a continuation-in-part of U.S. application 6 Serial No. 07/274,071, f~ed November 21,1988, subsequently abandoned, which applications 7 and issued patents are incorporated herein by reference in full and to which we claim priority under 8 35USC~20.

9 FieldoftheInvention This invention relates to biocompatible conjugates and, specifically, to pharmaceutically 11 acceptable, nonimmunogenic compositions comprising one or more glycosaminoglycans, or 12 derivatives thereof, conjugated to a synthetic hydrophilic polyrner such as polyethylene glycol 13 ~EG), which is optionally conjugated to collagen as well.

14 Background of the Invention Daniels et al, U.S. Pat. No. 3,949,073, disclosed the preparation of soluble collagen by 16 dissolving dssue in aqueous acid, followed by enzymatic digestion. The resuldng atelopeptdde 17 collagen is soluble, and substantially less imrnunogenic than unrnodified collagen. It may be 18 injected into suitable locadons of a subject with a fibril-formadon promoter (described as apolym-19 erizadon promoter in the patent) to form fibrous collagen implants in situ, for augmendng hard or soft dssue. This material is now commercially available from Collagen Corporation (Palo Alto, 21 CA) under the trademark Zyderm~\ Collagen Im~lant.
22 Luck et al, U.S. Pat. No. 4,48~,911, disclosed a method for preparing collagen in solution 23 (CIS), wherein nadve collagen is extracted from animal dssue in dilute aqueous acid, followed by 24 digesdon with an enzyme such as pepsin, trypsin, or Pronase~D, a tradernark of ATnerican Hoechst Corporadon, Somerville, Nl. The enzymatic digesdon removes the telopepdde portions of the 26 collagen molecules, providing "atelopepdde" collagen in solution. The atelopepdde C IS so pro-27 duced is substandally nonimmunogenic, and is also substandally non-crosslinked due to loss of the ;iii ~ ' .

2 ~

prirnary crosslinking regions. The CIS may then be precipitated by dialysis in a moderate shear 2 environment to produce collagen fibers which resemble native collagen fibers. The precipitated, 3 reconstituted fibers rnay addidonally be crosslinked using a chemical agent (for exarnple, aldehydes 4 such as formaldehyde and glutaraldehyde), heat, or radiation. The resulting products are suitable for use in medical implants due to their biocompatability and reduced imrnunogenicity.
6 Wallace et al, U.S. Pa~ No. 4,424,208, disclosed an improved collagen formulation 7 suitable for use in soft tissue augmentadon. Wallace's formulation comprises reconstitut~d fibrillar 8 atelopepdde collagen (for example, ZydermtD Collagen) in combination with particulate, g aosslinked atelopeptide collagen dispersed in an aqueous mediurn. The addition of par~culate crosslinked collagen irnproves the implant's persistence, or ability to resist shr;nlcage following 11 implantation.
12 Smestad et al, U.S. Pat. No. 4,582,640, disclosed a glutaraldehyde crosslinked 13 atelopeptide CIS preparation (GAX) suitable for use in medical implants. The collagen is aoss-14 linked under conditions favoring intrafiber bonding rather than interfiber bonding, and provides a product vith higher persistence than non-aosslinked atelopeptide collagen. Said product is com-16 mercially available from Collagen Corporation under the trademark Zyplast~ Collagen Irnplant.
17 Nguyen et al, U.S. Pat. No. 4,642,117, disclosed a method for reducing the viscosity of 18 atelopeptide CIS by mechanical shearing. Reconstituted collagen fibers are passed through a fine-19 mesh saeen until viscosity is reduced to a practical level for injection.Nathan et al, U.S. Pat. No. 4,563,350, disclosed osteoinductive bone repair compositions 21 comprising an osteoinductive factor, at least 5% nonreconstituted (afibrillar) collagen, and the 22 remainder reconstituted collagen and/or mineral powder (e.g., hydroxyapatite). CIS may be used 23 for thc nonresonstituted collagen, and Zyderrnt!D Collagen Implant (ZCI) is preferred for the 24 reconstituted collagen component. The material is implanted in bone defects or fractures to speed ingrowth of osteoclasts and promote new bone growth.
26 Chu, U.S. Pat. No. 4,557~764, disclosed a "second nucleation" collagen precipitate which 27 exhibits a desirable malleability and putty-like consistency. Collagen is provided in solution (e.g., 28 at 2-4 mg/mL), and a "first nucleation product" is precipitated by rapid titration and centrifugation.
29 The remaining supernatant (containing the buLk of the original collagen) is then decanted and allowed to stand overnight. The precipitated second nucleation product is collected by centri-~l3~74~l fugation.
2 Chu, U.S. Pat. No. 4,689,399, disclosed a collagen membrane preparation, which is 3 prepared by compressing and drying a collagen gel. The resulting product has high tensile 4 s~rength.
Silver et al., U.S. Pat. No. 4,703,108, disclosed the preparation of a sponge prepared by 6 crosslinking insoluble collagen using dehydrothermal means or by using cyanamide. Berg et al., 7 U.S. Pat. No. 4,837,285, disclosed the preparation of collagen in bead form for soft tissue 8 augmentation. Brodsky et al., U.S. Pat. No. 4,971,954, have disclosed a method of crosslinking 9 collagen using ribose or other reducing sugars.
Miyata et al., Japanese patent application 4-227265, published August 17, 1992, discloses 11 a composition comprised of atelopeptide collagen linked to a polyepoxy compound. The 12 composition is injected into the body to obtain sustained skin-lifting effects.
13 J.A.M. Ramshaw et al, Anal Biochem (1984) ~U:361-65, and PCT application 14 W087/04078, disclosed the precipitation of bovine collagen (types I, II, and m) from aqueous PEG soludons, where there is no binding between collagen and PEG.
16 Werner, U.S. Pat. No.4,357,274, disclosed a method for improving the durability of 17 sclero protein (e.g., brain meninges) by soaking the degreased tissue in hydrogen peroxide or 18 polyethylene glycol for several hours prior to Iyophilization. The resulting modified whole tissue 19 exhibits increased persistence.
Hiroyoshi, U.S. Pat. No. 4,678,468, disclosed the preparation of polysiloxane polymers 21 having an interpenetradng network of water-soluble polymer dispersed within. The water-soluble 22 polymer may be a collagen derivative, and the polymer may additionally include heparin. The 23 polymers are shaped into artificial blood vessel grafts, which are designed to prevent clotting.
24 Other patents disclose the use of collagen preparations incorporating bone fragments or mincrals. For example, Miyata et al, U.S. Pat. No.4,314,380, disclosed a bone implant prepared 26 by baking anlmal bone ægments, then soaking the baked segments in a solution of atelopeptide 27 collagen. Deibig et al, U.S. Pat. No.4,192,021, disclosed an implant material which comprises 28 powdered calcium phosphate in a pasty forrnulation with a biodegradable polymer (which may be 29 collagen). Commonly owned U.'3. application Serial No. 061855,004, filed April 22, 1986, now abandoned, disclosed a particularly effective bone repair materia1 comprising autologous bone ~ ~ ;

'.~.tr ~: ~i3 57~
176-88C~PB
rnaIrow, collagen, and particulate calciurn phosphate in a solid, rnalleable fornmllation.
2 There are several references in the art to proteins modified by covalent conjugation to 3 polymers to alter the solubility, antigenicity, and biological clearance of the protein. For example, 4 U.S. Pat. No. 4,261,973 disclosed the conjugation of several allergens to PEG or PPG
(polypropylene glycol~ to reduce the proteins' immunogenicity. U.S. Pat. No. 4,301,144 dis-6 closed the conjugation of hemoglobin with PEC; and other polymers to increase the protein's 7 oxygen-carrying capability. EPO 98,110 disclosed coupling an enzyme or interferon to a poly-8 oxyethylene-polyoxypropylene (POE-POP) block polymer to increase the protein's half-life in 9 serum. U.S. Pat. No. 4,179,337 disclosed conjugating hydrophilic enzymes and insulin to PEG
or PPG to reduce immunogenicity. Davis et al, ~ancet (1981) ;~:281-83, disclosed the enzyme I l uricase modified by conjugation with P3~G to provide uric acid metabolism in serurn having a long 12 half-life and low immunogenicity. Nishida et al, LPharm Pharmac~l (1984) 36:35~55, disclosed 13 PEG-uricase conjugates administered orally to chickens, demonstrating decreased serum levels of 14 uric acid. Inada et al, Biochem & Biophvs Res Comm (1984) ~:845-50 disclosed lipoprotein l~pase conjugated with PEG to render it soluble in organic solvents. Takahashi et al, Biochem 16 Bio~hvs Res Cornm (1984) 121:261-65, disclosed HRP conjugated with PEG to render the 17 enzyme soluble in benzene. Abuchowski et al, Cancer Biochem Biopl~ (1984) ~:175-86, -18 disclosed that enzymes such as asparaginase, catalase, uricase, arginase, trypsin, superoxide dis-19 mutase, adenosine deaminase, phenylalanine ammonia-lyase and the like conjugated with PEG
exhibit longer half-lives in serum and decreased immunogenicity. However, these references are 21 essentially concerned with modifying the solubility and biological characteristics of proteins 22 administered in low concentrations in aqueous solution.
23 M. Chvapil et al, l Biomed Mater Res (1969) ;~:315-32, disclosed a composition prepared 24 f~om collagen sponge and a crosslinked ethylenc glycol monomethacrylate-ethylene glycol dimethacryl~te hydrogel. The collagen sponge was prepared by lyophilizing an aqueous mixture of 26 bovine hide collagen and me~hyl,glyoxal, a tanning agent. The sponge-hydrogel composition was 27 prepared by polymerizing ethylene glycol monomethacrylate and ethylene glycol dimethacrylate in 28 the sponge.
29 A series of related patents disclose various types of collagen-containing materials. The patents are U.S. Patent 4,703,108, issued October 27, 1987; 4,861,714, issued August 29, 1989;

~13`~745 :

4,863,856, issued September 5, 1989; 4,925,924, issued May 15, 1990; 4,970,298, issued 2 November 13, 1990; and 4,997,753, issued March 5, 1991. All of these patents disclose collagen 3 materials wherein type I, Il, and m collagens aIe contacted with a crosslinking agent selected from 4 the group consisting of a carbodiilnide or a succinirnidyl active ester. Various types of treatrnent may be carried out prior to or after crosslinking in order to form particular types of desired 6 materials such as sponges and/or sheets.
7 In U.S. Patent No. 5,162,430, we described chemical conjugates whereby various forrns 8 of collagen were conjugated using synthetic Xydrophilic polymers such as polyethylene glycol.
9 Such conjugates are useful for a variety of applications, such as soft tisspe augrnentation and the formation of implants useful in bone repair. In U.S. application Serial No. 07/907,518, we 11 disclose that it is possible to form such conjugates with biomaterials other than collagen.
12 S~ecifically, synthetic hydrophilic polyr~ers are used to crosslink insoluble biocompatible, 13 biologically inert (preferably naturally occurring) polyrners other than collagen. Activated 14 polyethylene glycol is the preferred crosslinking agent. We now describe specific biocompatible polymer conjugates and their methods of synthesis, which include conjugates of 16 glycosaminoglycans, and/or their derivatives, which can be used in a manner sirnilar to the 17 collagen-polymer conjugates described in our earlier, above-referenced U.S. Patent No.
18 5,162,430, which is incorporated herein by reference.

19 ~mmarvoftheInvention Biocompatible, pharmaceutically acceptable, nonimrnunogenic conjugates are formed by 21 covalently binding glycosaminoglycans, and/or derivatives thereof, to a synthetic hydrophilic 22 polymer, such as an activated polyethylene glycol, and optionally covalently binding the conjugate 23 to collagen.
24 The synthedc hydrophilic polymer is preferably an activated polyethylene glycol or a derivative thereof having an average molecular weight in the range of about 100 to about 100,000, 26 preferably between 1,500 to 20,0()0. Compositions comprising the conjugates may optionally 27 include other components such as pharmaceutically acceptable fluid carriers to form injectable 28 formulations, and/or biologically active proteins such as cytol~nes or growth factors. Thc 29 biocompatible conjugates of the invention generally contain large amounts of water when fo~ned.
~.
S

.... ~ , .

7 ~ 5 The conjugates can be dehydrated to form relatively solid implants for hard dssue augmentation, 2 such as the rep ur or replacement of bone or cartilage. The dehydrated, solid irnplant can f~ther be 3 ground into pardcles which can be suspended in a nonaqueous fluid and injected into a living being 4 for soft tissue augrnentation. Once in place, the solid implants or particles rehydrate and expand in S size five-fold o. more.
6 The invention relates to biocompatible conjugates which may be used in a varie~ of 7 medical and pharmaceudcal applications. The most basic embodiment includes the biocompatible 8 eonjugates and pharmaceutical composidons forrnulated using these conjugates, which may 9 additionally include pharmaceutically acceptable carriers in different types and amounts. The eonjugates include a synthetic hydrophilic polymer, one or more type of glycosaminoglycan, and 11 optionally, collagen.
12 One of the most irnportant uses for the conjugates and compositions of the invendon is in 13 soft tissue augmentation. The compositions are formulated into a flowable forrn and injected into 14 patients, such as into facial areas, for the purpose of soft dssue augmentation. The method can be varied so that the reacdon between the glycosaminoglycan and the synthetic polymer occurs in situ.
16 Furthermore, the conjugates can be dehydrated and then ground into particles, suspended in an 17 inert nonaqueous carrier, and injected into a patient. After injecdon, the carrier will be removed by 18 natural physiological conditions and the particles will rehydrate and swell to their wiginal size.
19 The conjugates ean further be molded into a desired shape, then dehydrated to form a solid implant for use in hard tissue augmentation, such as for the repair or replacement of cartilage or 21 bone.
22 The conjugates of the inv~ndon ean be combined with eytokines or growth factors. The 23 eytokines ean be either simply admixed with the glyeosaminoglyean-synthetic polymer conjugate, 24 or ean be ehemieally eonjugated to di- or muld-funcdonally aetivated polyrner (e.g., glyeo~sarninoglycan-synthetie polymer-cytokine). In the ease of an admixture, the eylolcines or 26 g~owth faetors are not ehemieally bound to the eonjugate and may diffuse out from the site of 27 administradon into the surrounding dssue, providing for sustained release and loeal therapeude 28 effeets. In the ease of the eytokine or growth factor being ehemieally conjugatcd to the polyrner 29 eonjugate, the eytokine or grow~ factor retains its biologieal activity while bound to the conjugate and may also be released by erosion of the polymer eonjugate.

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'ir'.. '': . ~ ' : ' - - : :

~13`'5 7~5 176-88CIP~
The conjugates of the invention, and compositions containing such conjugates, are useful 2 in a wide range of therapeutic applications. For example, the conjugates are useful in dermal 3 wound healing and cardiovascular applications where isnmunological reactions are to be n~inimized 4 or blood coagulation is to be avoided. The conjugates rnay also be used in various ophthalmic applications, such as vitreous fluid replacement, corneal shields for delivery of drugs to the eye, or 6 as lenticules. Other indications include use of the conjugates in orthope~c surgery or as joint 7 lubricants in the treatment of arthritis. O~her potential uses for the conjugates are as an injectable 8 drug or cell delivery system, as a dermal wolmd dressing, or as a coating for solid implants 9 intended for long-term use in the body.
The conjugates can filrther be made into a variety of forrns, including, but not limited to, 11 membranes, beads, sponges, tubes, sheets, and forrned irnplants. Formed implants can be used as 12 prosthetic devices for replacement or augrnentation of various organs and body parts such as heart 13 valves, patellas, ears, noses, cheekbones, etc.
14 A primary feature of the invention is to provide biocompatible conjugates fonned by cl)valendy binding syndletic polymers such as activated polyethylene ~Iycol to one or more species 16 of glycosaminoglycan.
17 Another feat~e of the invention is to provide glycosaminoglycan-synthetic polyrner 18 conjugates which are further covalently bound to collagen.
19 Another feature of the invention is to proYide pharmaceutically acceptable, nonimrnunogenic compositions comprising phamnaceutically acceptable lluid carriers in which the 21 conjugates are dispersed.
22 Another feature of the invention is to provide a method of tissue augrnentation comprising 23 forrning biocompadble glycosaminoglycan-synthetic polymer conjugates, dehydrating the 24 conjugates to form a solid, grinding the solid into particles, suspending the pardcles in a pharrnaceutically acceptable nonaqueous fluid carrier, and injecting the suspension into the site of 26 augrnentadon, after which the parlicles will rehydrate and expand in sizc.
27 An irnponant advantage of the present inventdon is that the glycosarninoglycan-synthcdc 28 polyrncr conjugates nave a greata degree of stability in vivo as cornpared with conventdonal 29 glycosaminoglycan composidons.

~13 ~74 ~

l76-sscrPg Another feature of the invention is ~at the glycosaminoglyean-synlhetic polyrner2 eonjugates ean be formed using a range of different molecular weight synthetic polymers in order 3 to adjust the physical charaeteristics of the composition.
4 Another advantage of the present invention is that the glycosaminoglycan-synthetic polymer S eonjugates have superior handling charactelistics as compared with conventional 6 glycosaminoglycan compositions.
7 Another advantage of the present invention is that the glycosaminoglycan-synthetic polymer 8 conjugate compositions generate a decreased ilrunune reaction as compared with conventional 9 collagen compositions.
Anothçr advantage of the present invention is that the glycosaminoglycan-synthetic polymer 11 conjugate compositions have irnproved moldability, malleability, and elas~city as compared with 12 conventional glycosaminoglycan compositions.
13 Other features of the present invention include the ability to formulate dle compositions and 14 conjugates in combination ~,vith pharrnaceutieally active proteins such as cytokines or growth factors in order to improve the activity and available half-life of sueh eytokines or growth factors 16 under physiologieal eonditions.
17 Another feature of the present invention is that the glycosaminoglyeans or derivatives ~ ~
18 thereof may be bound to the synthetie polymer by means of a variety of types of covalent linkages ~ ~ -19 ineluding ester and ether linkages. -Another advantage of the present invendon is that an ether linkage may be used to form the 21 covalent bond to ereate the eonjugate and this bond is resistant to hydrolysis.
22 Another advantage of the invention is that the three-part eonjugates eomprising eovalently 23 bonded glyeosaminoglyean-synthetie polymer-collagen have dfflerent physieal and ehemieal 24 properdes than either glyeosaminoglycan-synthede polymer eonjugates or eollagen-synthede polymer eonjugates alone, whieh properties can be manipulated as desired by varying the rdative 26 ratios of g1yeosarninoglyean and eollagen in the eomposition.
27 These and other features of the present invention will become apparent to those skilled in 28 the art upon reading the details of the strueture, synthesis, and usage of the glyeosaminoglyean-29 synthetie polymer conjugates set forth below.

2~3`-~7~

Detailed Descn~tion ~Lf the Pref~arçd Embodimen~ of the Inven~on 2 It must be noted that, as used in this specification and the appended claims, the singular 3 forms "a", "an", and "the" include plural referents unless the context c1early dictates otherwise.
4 Thus, for example, reference to "a polymer" includes rnixtures of such polymers, reference to "an S attaching group or a linking group" includes one or more different types of groups known by those 6 s~lled in the art or capable of forming a covalent bond, and refeIence to "the synthetic polymer"
7 includes rnixtures of different types of synthetic polymers such as various activated polyethlene 8 glycols and so forth.
9 Unless defined otherwise, all technical and scientific tenns used herein have the sarne meaning as commonly understood by one of ordinary sl~ll in the art to which this invention I l belongs. Although any methods and materials similar or equivalent to those described herein rnay 12 be useful in the practice or testing of the present invention, only the preferred methods and 13 rnaterials are described below; it is not inteneded that the invention be limited to these preferred 14 embodirnents, however.
All publications mentioned herein are incorporated herein by referenee. Further, speeific 16 terminology of particular irnportance to the description of the present invention is defined below.

17 Definitions 18 The terrn "glyeosarninoglycan" is intended to encompass complex polysaccharides which 19 are not biologieally active (i.e., not eompounds such as ligands or proteins) having repea~ng units of either the same saccharide subunit or two different sacc haride sùbunits. Some examples of 21 glyeosalTunoglyeans include dermatan sulfate, hyaluronic aeid, the chondroitin sulfates, ehitin, 22 heparin, keratan sulfate, keratosulfate, and derivatives thereof. In general, the glycosaminoglyeans 23 are extracted from a natural souree and pu-ified and derivatized. However, they may be 24 synthetieally produeed or synthesized by modified mieroorganisms sueh as baeteria.
2S The term "hyaluronie aeid" is intended to eneompass naturally oeeurring and synthe~e 26 forrns of the polymer~C8HI3O4N)n-(C6H8os)no~n=l to n= about 5,000), and derivatives 27 thereo Partieularly preferred derivatives inelude thoæ having funetionalized moieties whieh 28 allow ehemieal reaetion with another molecule to form a eovalent bond, such as deacetylated 29 hyaluronie aeid. The eompound ineludes altemating units of l,~linked N-aeetylglueosarnine and 2 1 3 ~

176-~8CIP8 glucuronic acid u uts. Hyaluronic acid is a viscous, high molecular weight mucopolysaccharide 2 found in m~nrnalian fluids and connective tissue. The formula for hyal~onic acid is shown 3 below.

4 ~valuronicAcid ,__ OH H NHCOCH3 , S Alternating units of l,~linked 6 N-acetylglucosamine and glucuronic acid 7 wherein n ranges from I to about 5,000.

213 ~74a 176-88~1P8 The terrn "chondroitin sulfate", as used herein, is intended to encompass dlr~e major 2 compowlds: chondroitin sulfate A, dermatan sulfate (also known as chondroitin sulfate B, which 3 is an isomer of chondroitin sulfate A), and chondroitin sulfate C. The structures of these three :
4 compounds are shown below.

Chondroitin S~fate A ~:
. : :

-, COOH HO3S CH20H
~,~

, _ OH H NHCOCH3 3 Repeating unit of chondroitin sulfate A

4 wherein n ranges from about 10 to about 300;

Chondroitin Sulfate C

COOH CU2OSO3H ~ ~:

7 Repeating unit of chondroitin sulfate C

8 wherein n ranges from about 20 to about 200; -9 Dermatan Sulfate ~ HO3S CH2OH
H/c~H ~

j ~ V ~H , . ..
, _ OH H NHCOcH3 ' n 3Repeating unit of dennatan sulfate 4 (chondroitin sulfate B) 5 wherein n ranges from about 10 to about 300.

2~ 3`~7~5 ~

The term "chitin" is intended to encompass polymers comprising repeating units of N-2 acetylglucosamine. The structure of chitin is shown below.

3 Chitin _ H Ntl-CO-CH ~ ~ I aH-CO-CH3 n N-Acetyl~lucosamine N-Acet~lQlucos~mine wherein n ranges from about 500 to about 2,000.

13 -~

- 2~3i~7~

The term "chitosans" Iefers to both partially and fully deacetylated chitins. The tenn 2 "chitosan 1" refers to par~ally deacetylated chitin, as shown below. : :

3 Chitosan 1 CH20H CH20H , "
'~
H NH-CO-CH3 H NH2 n N-Acetyl~lucosamine :
','' ,'~
4 ff'artially deacetylated chitin) :
S wherein n ranges from about 500 to about 2,000.

,~

~- 213-~7~ 176-8~IP8 The term "chitosan 2" refers to fully deacetylated chit~, as shown below.

2 Chitosan 2 H NH2 H NH2 n 3 (Fully deacetylated chitin) 4 wherein n ranges from about 500 to about 2,000.
. The term "keratan sulfate" refers to polymers having the repeating structure shown below.

6 Keratan Sulfate OH OH I H

4 Repeating unit of keratan sulfate S wherein n ranges from about 10 to about 100. ~ ~:

~:

-DEC 28 '9~ 08:46RM FILLMORE & RILEY I~P~i P.2~2 . ~- 213~74 1 176-~8ClP8 The ce~n "ke~atosulfa~e" refers to a polym~ rhat is an iSDl'nel ~ l~eratall Slllfate. ha~illg the 2 repea~2g s~cn~re shown below.
3 Keratosu~fa~

~ ~' H OH H NHCOCH3 .
11 R~peadng Ullit of J~ osulfate 12 wherein n ranges f~om about 10 to about 100, 13 The term "he~a~in" rdcrs to polyrr~s compris~ng alterna~ng units of sul~ated glusosan~ne 14 and s~fated gluclrronic acid, as shawn ~elow.

H NH-SO3H H OSO3H n :

Sulfated glucos4min~ Sulfat6d ~lucuronic acid wher~ n ranges ~om about 2 to about 3,000.

16 ;

2134~4~ ~

The terms "biologically inert polymers", "biocompatible polymers", and "biologically inert, 2 biocompatible polyrners" are used interchangeably herein. The terms refer to biologically inert, 3 insoluble, biocompatible polymers and their derivatives which can be covalently bound to synthetic 4 hydrophilic polymers to form the conjugates of the invention. These terms encompass polymers S that are biologically inert, insoluble, nontoxic and do not generate any appreciable irnrnune reaction 6 when incorporated into a living being such as a human.

7 Preferred synthetic polymers for use in the present invention are hydrophilic and are highly 8 pure or are purified to a highly pure state such ~hat the polymer is or is treated to become 9 pharmaceutically pure so that it may be injected into a human patient. Most hydrophilic synthetic polymers can be rendered water-soluble by incorporating a suff1cient number of oxygen (or less fre-11 quently nitrogen) atoms available for forming hydrogen bonds in aqueous solutions. Preferred 12 synthetic polymers are hydrophilic but not necessarily water-soluble. Hydrophilic synthetic 13 polymers used herein include activated forrns of polyethylene glycol (PEG), polyoxyethylene, poly-14 methyl~ne glycol, polytrimethylene glycols, polyvinylpyrrolidones, and derivatives thereof with activated PEG being particularly preferred. The synthetic polymers can be linear or multiply 16 branched, but are typically not substantially crosslinked. Other suitable hydrophilic synthetic 17 polyrners include polyoxyethylene-polyoxypropylene block polymers and copolymers. Polyoxy-18 ethylene-polyoxypropylene block polymers having an ethylene diarnine nucleus (and thus having 19 four ends) are cornrnercially available and rnay be used in the practice of the invention. Naturally occurring polymers such as proteins, starch, cellulose, heparin, hyaluronic acid and derivatives 21 thereof and the like are expressly excluded from the scope of this definition. All suitable synthetic 22 polymerswill be non-toxic, non-inflammatory, and nonimmunogenic when administered 23 subcutaneously, and will prefcrably be essentially nondegradable in vivo over a period of at least 24 several months. The hydrophilic synthetic polymer may increase the hydrophilicity of the conjugate, but does not render it water-soluble. The most preferred hydrophilic synthetic polymers 26 include mono-, di-, and muldfunctionally acdvated polyethylene glycols. Monofuncdonally 27 acdvated PEG has only one reactive hydroxy group, while difunctionally activated PEG has 28 reacdve groups at each end. Monofuncdon~lly acdvated PEG preferably has an average rnolecular 29 weight between about 100 and about 15,000, more preferably between about 200 and about 8,000, and most preferably about S,000. Difunctionally acdvated PEG preferably has an average 31 molecular wdght of about 400 to about 40,000, more preferably between about 3,000 to about .~:'',;' '' `, ', , ' :
",~':;"' ' '' " ' ' ' ' ' i ~,~ ` ' ' ' ,.' ` ~13.~7~j 176-~8CIP~3 10,000. Multifunctionally ac~vated PEG preferably has an average molecular weight between 2 about 3,000 and 100,000.
3 PEG can be rendered monofunctionally activated by forming an alkylene ether group at one 4 end. The alkylene ether group rnay be any suitable alkoxy radical having 1~ carbon atoms, for S exasnple, methoxy, e~hoxy, propoxy, 2-propoxy, butoxy, hexyloxy, and the like. Methoxy is pres-6 ently preferred. Difunctionally activated PEG is provided by allowing a reactive hydroxy group at 7 each end of the linear molecule. The reactive groups are preferably at dle ends of the polyrner, but 8 rnay be provided along the length thereof. Multifunctionally activated synthetic polyrners are 9 capable of crosslinldng ~he compositions of dle invention, and may be used to attach cyto~nes or growth factors to the glycosaminoglycan-synthetic polymer conjugate.

11 The term "nonimmunogenic" refers to molecules and compositions which produce no 12 appreciable imrnunogenic or allergic reaction when injected or otherwise implanted into the body of 13 a human subject.

14 The term "chemically conjugated" as used herein means attached dlrough a covalent che~ueal bond. In dhe practice of dhe invention, a hydrophilic synthetic polymer and a 16 glyeosaminoglycan or derivative thereof may be chemieally eonjugated by using a linking radical, 17 so that the hydrophilie synthetie polymer and glycosaminoglycan are eaeh bound to the radieal, but 18 not directly to eaeh other. The term "biocompatible conjugate" refers to a biologieally inert, 19 bioeompatible polymer chemieally eonjugated to a hydrophilic synthetie polymer, within the meaning of this invention. For example,"PEG-hyaluronie aeid" denotes a eomposition of the 21 invention wherein hyaluronie acid is ehemieally eonjugated to PEG. The hydrophilie synthetie 22 polymer may be "ehemically eonjugated" to the glyeosaminoglyean such as hyaluronie aeid by 23 means of a number of different types of ehemieal linkages. For example, the eonjugation can be 24 via an ester or a urethane linkage, but is more preferably by means of an ether linkage. An ether linkage is prefelTed in that it ean be formea without the use of toxie ehemieals and is not readily 26 suseeptiUe to hydrolysis in vivo.
27 Those of ordinary skill in the art will appreeiate that hydrophilie synthetie polymers sueh as 28 polyethylene glyeol eannot be pre~pared praetieally to have exact moleeular wdghts, and that the 29 term "moleeular weight" as used herein refers to the average moleeular weight of a number of rnoleeules in any given sample, as eommonly used in the art. Thus, a sample of PEG 2,000 r~ught 31 eontain a stadstical mixture of polymer molecules ranging in weight from, for example, 1,500 to ' ~
`, ;.

.
.~
,j , 213~745 2,500, ~,vith one molecule differing slightly fiom the next over a range. Specification of a range of 2 molecular weight indicates that the average molecular weight may be any value between the lirnits 3 specified, and may include molecules outside those limits. Thus, a molecular weight range of 4 about 800 to about 20,000 indicates an average molecular weight of at least about 800, ranging up to about 20,000.
6 The term "available Iysine residue" as Hsed herein refers to lysine side chains exposed on 7 the outer surface of natural polymer molecules, which are positioned in a rnanner to allow reaction 8 with activated PEG. The n lmber of available lysine residues may be deterrnined by reaction with 9 sodium 2,4,6-trinitrobenænesulfonate (TNBS).
The terms "treat" and "treatrnent" as used herein refer to augrnentation, repair, prevention, 11 or alleviation of defects, particularly defects due to loss or absence of soft tissue or soft tissue 12 support, or to loss or absence of bone. Additionally, "treat" and "treatrnent" also refer to the pre-13 vention, maintenance, or alleviation of disorders or disease using a biologically active protein 14 coupled to a conjugate-containing composition of the invention. Accordingly, treatrnent of soft tis-sue includes augmentation of soft tissue, for exarnple, irnplantation of conjugates of the invention 16 to restore normal or desirable derrnal contours, as in the removal of dermal creases or furrows, or 17 as in the replacement of subcutaneous fat in maxillary areas where the fat is lost due to aging, or in 18 the augmentation of submucosal tissue, such as the urinary or lower esophageal sphincters.
19 Treatment of bone and cartilage includes the use of biocompatible conjugates, particularly in com-bination with suitable particula e materials, to replace or repair bone tissue, for example, in the treat-21 ment of bone nonunions or fractures. Treatment of bone also includes use of conjugate-containing 22 compositions, with or without additional bone growth factors. Compositions comprising 23 conjugates with ceramic particles, preferably hydroxyapatite and/or tricalcium phosphate, are par-24 ticularly useful for the repair of stress-bearing bone due to its high tensile strength.
The terms "cytokine" and "growth factor" are used to describe biologically active moleculcs 26 and active peptides (which may Ibe either naturally occurring or synthetic) which aid in healing or 77 regrowth of normal tissue inclucling growth factors and activc peptides. The function of cytokines 28 is two-fold: 1) they can incite local cclls to produce new collagen or ~dssue, or 2) they can at~ract 29 cclls to the site in need of correction. As such, cytokines and growth factors serve to encourage "biological anchoring" of the im~lant within the host tissue. As previously described, thc 31 cytokines can either be admi~ced with the conjugate or chcrnically coupled to the conjugate. For "I , . .
.,., . ~
., `

. ~ .
.,. j ~ ~ .

"' , ~.: ,. ' , ~13`17~ ,~
176-88CIP~
exarnple, one may incorporate cytokines such as interferons (lFN), tumor necrosis factors (~), 2 interleukLns, coiony stirnulating factors (CSFs), or growth factors such as osteogenic factor extract 3 (OFE), epidermal growth factor (EGF), transforrning growth factor (TG~;) alpha, TGF-B
4 (including any combination of TGF-Bs), TGF-Bl, TGF-B2, platelet derived growth factor (PDGF-S AA, PDGF-AB, PDGF-BB), acidic fibroblast growth factor (FGF), basic FGF, cormective tissue 6 activating peptides (CTAP), B-thromboglobulin, insulin-like growth factors, ~rythropoietin (EPO), 7 nerve growth factor (NGF), bone morphogenic protein (P.MP), osteogenic factors, and the like.
8 Incorporation of such cytokines, and appropriate combinations of cytokines and growth factors can 9 facilitate the regrowth and rernodeling of the implant into normal tissue, or may be used in the treatment of wounds. Further, one may chemically link the cytokines or growth factors to the 11 glycosaminoglycan-synthetic polymer conjugate by employing a suitable amount of multifunc-12 tionally activated synthetic polymer molecules during synthesis. The cytokines or growth factors 13 may then be attached to the functional sites of the multifunctionally activated synthetic polymers by 14 the same method used to attach activated PEG to glycosaminoglycans, or by any other suitable rnethod. By tethering cytokine or ~owth factor molecules to the implant, the arnount of cytokines 16 or growth factor required to be therapeutically effective is substantially reduced. Conjugates 17 incorporated with cytokines or growth factors rnay serve as effective controlled release drug 18 delivery means. By varying the chemical linkage between the glycosaminoglycan and the synthetic 19 polymer, it is pGssible to vary the effect with respect to the release of the cytokine or growth factor.
For example, when an "ester" linkage is used, the linkage is more easily broken under 21 physiological conditions, allowing for sustained release of the growth factor or cytokine from the 22 matrix. However, when an "ether" linkage is used, the bonds are not easily broken and the 23 cytokine or growth factor will remain in place for longer p~iods of time with its active sites 24 cxposed, providing a biological eFfect on the natural substrate for the active site of the protein. It is possible to include a mixture of conjugates with different linkages so as to obtain variations in the 26 effect with respect to the release of the cytokine or growth factor, i.e., the sustained relcase effect 27 can be modified to obtain the des;~ed rate of release.
28 The term "effecdve amoune" refcrs to the amount of compositdon required in order to obtain 29 the effect desired. Thus, a "tissuc growth-promoting amount" of a composition containing a cytokine or growth factor refers to the arnount of cytokine or growth factor needed in order to 31 stDnulate tissue grow~ to a detectable degree. .Tissue, in this context, includes connective tissue, :, ~.. . .. .
,. !7,-"~

.:.`'-.'.

2 1 3 ~ 7 ~ 5 l76-88CIP8 bone, cartilage, epiderrnis and dermis, blood, and other tissues. The actual amount which is 2 deterrnined to be an effective amount will vary depending on factors such as the size~ condition, 3 sex and age of the pa~ient and can be more readily detern~ined by the caregiver.
4 The term "sufficient amount" as used herein is applied to the amount of carrier used in combination with the conjugates of the invention. A sufficient amount is that amount which, when 6 mixed with the conjugate, renders it in the physical form desired, for exarnple, injectable solution, 7 injectable suspension, plastic or malleable implant, rigid stress-bearing implant, and so forth.
8 Injectable formulations generally include an amount of fluid camer suffilcient to render the 9 composition smoothly injectable, whereas malleable implants have substantially less carrier and have a clay-like consistency. Rigid stress-bearing implan~s may include no carrier at all and have a I l high degree of structural integrity. ~he arnount of the carrier can be varied and adjusted depending 12 on the particular conjugate used and the end result desired. Such adjustments will be apparent to 13 those skilled in the art upon reading this disclosure.
14 The term "suitable particulate material" as used herein refers to a particulate material which l 5 is substantially insoluble in water, nonirnmunogenic, biocompatible, and imrniscible with collagen-16 polymer conjugate. The particles of material may be fibrillar, or rnay range in size from about 20 17 to 250 llm in diameter and be bead-like or irregular in shape. Exemplary particulate materials 1 B include without limitation fibrillar crosslinked collagen, gelatin beads, crosslinked collagen~PEG
l 9 particles, polytetrafluoroethylene beads, silicone rubber beads, hydrogel beads, silicon carbide beads, and glass beads. Preferred par~culate materials are calcium phosphates, most preferably 21 hydroxyapatite and/or tricalcium phosphate particles.
22 The term "solid implant" refers to any solid object which is designed for inserdon and use 23 within the body, and includes bone and car~lage implants (e.g., ar~lcial joints, retaining pins, 24 cranial p]ates, and the like, of metal, plasdc and/or other materials), breast implants (e.g., silicone gel envdopes, foam forms, iand the like), catheters and cannulas intended for long-terrn use 26 (beyond about three days), ar~ficial organs and vessels (e.g., ar~ficial hearts, pancreascs, kidneys, 27 blood vessels, and the like), drug delivery devices (including monolithic implants, pumps and con-28 1rollcd release devices such as Alzct~lD minipurnps, steroid pellets for anabolic growth or 29 contraception, and the like), sutures for derrnal or internal use, periodontal membranes, lenticules, comeal shields, platinum wires for aneurysrn treatment, and the like.

. ( ,, - : .
. jr~
,`~` "' ' ' ': ' , ' ' : '.,i". , 2~3 74:i The term "suitable fibrous material", as used herein, refers to a fibrous material which is 2 substantially insoluble in water, nonimrnunogenic, biocompatible, and immiscible with the 3 biocompatible conjugate of the invention. The fibrous material may comprise a variety of materials 4 having these characteristics and are combined with compositions of the conjugate in order to ~orm 5 and/or provide structural integrity to various irnplants or devices used in connection with medical 6 and pharmaceutical uses. For example, the conjugate compositions of the invention can be coated 7 on the "suitable fibrous material" which can then be wrapped around a bone to provide structural 8 integrity to the bone. Thus, the "suitable fibrous material" is useful in forming the "solid implants"
9 of the invention.
The term "in situ" as used herein means at the site of administration. Thus, the injectable 11 reaction mixture compositions are injected or other vise applied to a site in need of augrnentation, 12 and allowed to crosslink at the site of injection. Suitable sites will generally be intradermal or su~
13 cutaneous regions for augmenting dermal support, at the site of bone fractures ~or wound healing 14 and bone repair, and within sphincter tissue for sphincter augmentation ~e.g., for restoration of 15 continence).

16 The term "aqueous mixture" includes liquid solutions, suspensions, dispersions, colloids, 17 and the like containing a natural polymer and water.

18 The term "collagen" is used in its conventional sense to describe a material which is the 19 major protein component of the extracellular matrix of bone, cartilage, skin, and connective tissue 20 in animals and derivatives. Collagen in its native forrn is typically a rigid, rod-shaped molecule 21 approximately 300 nm long and 1.5 nm in diarneter. It is composed of three collagen polypeptides 22 which form a tight triple helix. The collagen polypeptides are characterized by a long rnidsection 23 having the repeating sequence -Gly-X-Y-, where X and Y are of len proline or hydroxyproline, 24 bounded at each end by the "telopeptide" regions, which constitute less than about 5% of the 25 molecule. The telopeptide regions of the collagen chains are typically responsible for- the cross-26 linking between chains, and for the im!nunogenicity of the protein. Collagen occurs in several 27 "types", having differing physical properties. The most abundant types are Types I-m. The 28 present disclosure includes these and other known types of collagen including natural collagen and 29 collagen which is processed or rnodified, i.e., various collagen derivatives. Collagen is typically 30 isolated from natural sources, such as bovine hide, cartilage, or bones. Bones are usually dried, 31 defatted, crushed, and demineralized to extract collagen, while hide and cartilage are usually , J

~. 21~7~5 rr~inced and digested with pro~olytic enzymes (other than collagenase). As collagen is resistant to 2 most proteolytie enzymes, this procedure conveniently serves to remove most of the contaminating 3 protein found with collagen.
4 - The term "dehydrated" means the rnaterial is air~ied or lyophilized to remove substantially S all unbound water.

6 General Method 7 To forrn the conjugates of the invention, glycosaminoglycans are, in general, chernically 8 derivatized and then covalently bound to a functionally activated hydrophilic synthetic polyrner.
9 This can be carried out using a nurnber of suitable methods. In accordance with one method, (1) the hydrophilic synthetic polymer is activated, (2) the glycosaminoglycan is subjected to 11 chemical modification by deacetylation and/or desulfa~on, and (3) the activated syn~etic polymer 12 is reaeted with the chemically modified glycosaminoglycan.

13 Activation of Polyethvlene Glvcol (PEGl 14 The first step in forming the eonjugates of the invention generally involves functionalization, or activation, of the synthetic hydrophilic polymer. Although different synthetic 16 hydrophilie synthetic polyrners ean be used in connection with forming the eonjugate, the polymer 17 must be bioeo~patible, hydrophilie, but relatively insoluble, and is preferably one or more forrns 18 of derivatized polyethylene glycol (PEG), due to its known biocompatibility. Various forrns of 19 derivatized PEG are extensively used in the modifieation of biologically aetive molecules because PEG ean be formulated to have a wide range of solubilities and beeause it laeks toxicity, ;
21 antigenicity, imrnunogenieity, and does not typically interfere with the enzymatic activities and/or 22 eonformations of peptides. Fur~hermore, PEG is generally non-biodegradable and is easily 23 exereted from most living organisms ineluding hurnans.
24 Various funetionalized polyeth~ylene glyeols have been used effeetively in fields sueh as protein modifieation (see Abuehlowski et al., EnzYrnes as Drues, John Wiley & Sons: New York, 26 NY (1981) pp. 367-383; and Dreborg et al., Crit. Rev. Therap. Dru~ Car~rier Svst. (1990) :315 ), 27 peptide ehemistry (see Mutter et al., The Peptides. Aeadernie: New York, NY 2:285-332; and 28 Zalipsky et al., Int. J. Pepdde Protein Res. (1987) ~:740), and the synthesis of polymerie drugs Z9 (soc&'dpsl~etal.,dur.Polvm.J.(198~ 1177 ardOuchdotal.,J.Macromol,Sci.-Chcm, '., , ., , ' ~3~74~

(1987) A24:1011). Various types of conjugat~s formed by the binding oî activated2 (funcdonalized) polyethylene glycol with specific pharmaceutically acdve proteins have been 3 disclosed and found to have useful medical applications in part due to the stability of such 4 conjugates with respect to proteolytic digestion, reduced immunogerucity, and longer half-lives within living organisms.
6 One form of polyethylene glycol which has been found to be particularly useful is 7 monomethoxy-polyethylene glycol (mPEG), which can be activated by the addition of a compound 8 such as cyanuric chloride, then coupled to a protein (see Abuchowski et al., J. Biol. Chem. (1977) 9 252:3578). Although such methods of activating polyethylene glycol can be used in connection with the present invention, they are not particularly desirable in that the cyanuric chloride is 11 relatively toxic and must be completely removed from any resulting product in order to provide a 12 pharmaceuticallyacceptablecomposition.
13 Activated forms of PEG, including activated forms of mPEG, can be made from reactants 14 which can be purchased commercially. One fomn of activated PEG which has been found to be partic~larly useful in connection with the present invention is mPEG-succinate-N-16 hydroxysuccinimide ester (SS-PEG) (see Abuchowski et al., Cancer Biochem. ;Biphvs. (1984) 17 7:175). Activated forrns of PEG such as SS-PEG react with the proteins under relatively mild 18 condidons and produce conjugates without destroying the speci~lc biological acdvity and specificity 19 of the protein attached to the PEG. However, when such activated PEGs are reacted with proteins, they react and form linkages by means of ester bonds. Although ester linkages can be used in 21 connection with the present invention, they are. not particularly preferred in dlat they undergo 22 hydrolysis when subjected to physiological conditions over extended periods of time (see Dreborg 23 et al., Crit. Rev. Therap. Drug CalTier Svst. (1990) ~:315; and Ulbrich et al., J. Makromol.
24 Chem. (1986) 187:1131).
It is possible to link PEG to proteins via urethane linkages, thereby providing a more stable 26 attachment which is more resistant to hydrolytic digestion than the ester linkages (see Zalipsky et 27 al., Polymeric Drug and Drug Delivery Systems, Chapter 10, "Succinimidyl Carbonates of 28 Polyethylene Glycol" (1991)). The stability of urethane linkages has been demonstrated under 29 physiological conditions (see Veronese d al., Appl. Biochem. Biotechnol. (1985) 11:141; and Lan1vood et al., J. Labelled Compounds ~adiopharrn. (1984) 21 :603). Another means of attaching 31 the PEG to a protein can be by means of a carbarnate linkage (see Beauchamp et al., Anal.
~4 , ~
.'~'' 2 ~ 3 -~ 7 4 ~

176-8~CIP8 Biochem. ~1983) 131:25; and Berger et al., Blood (1988) 71:1641). The carbamate linkage is 2 created by the use of carbonyldiimidazole-activated PEG. Although such linkages have 3 advantages, the reactions are relatively slow and rnay take 2 to 3 days to complete.
4 The various means of activating PEG described above and publications cited in connec~on with the activation means are described in connection with linking the PEG to specific biologically 6 active proteins and not inert~ biologically inactive, natural polymers. (See Polvmeric Drug and 7 Drug Deliverv Svstems, Chapter 10, "Succinimidyl Carbonates of Polyethylene Glycol" (1991).~
8 However, the present invention now discloses that such ac~vated PEG compounds can be used in 9 connection with the formation of inert, biocompatible conjugates. Such conjugates provide a range of improved, unexpected characteristics and as such can be used to form the various composit;ons 11 of the present invention.

l 2 Specific Forms of Activated PEG
13 For use in the present invention, polyethylene glycol is modified in order to provide 14 activated groups on one or, preferably, two or more ends of the molecule so that covalent binding can occur between the PEG and the free amino groups on the chemically derivatized 16 glycosaminoglycan. Some specific activated forms of PEG are shown structurally below, as are ; 17 generalized reaction products obtained by reacting activated forms of PEG with derivatized 18 glycosaminoglycans. In Formulas 1-7, the term GAG-PLYM is used to represent chemically 19 daivadzedglycosan~inoglycanpolymers.

, 25 :1 .~ ,. .

l .
:~ .
. .
.~ .
.~ .

~13~7~

The first activated PEG is difunctionally activated PE~G succinimidyl glutarate, referred to 2 herein as (SG-PEG~. The sauctural formula of this molecule and the reac~on product obtained by 3 reacting it with a glycosaminoglycan derivative are shown in Formula 1.

4S-PEG: Difunctionally Activated PEG Succinin~idyl Glutarate [~N-O-CO-(CH2)3-OC-O-PEG-O-CO-~CH2)3-CO-O-~ ;~

'.,, ~ r GAG-PLYM-HN-CO-(CH2)3-OC-O-PEG-O-CO-~CH2)3-CO-NH-PLYM-GAG

6 FOR~fULA I

,1 .

i 1 26 :
. ~

"' 2 1 3 ~ 7 L~l 3 Another difunctionally activated fonn of PEG is referred to as PEG succinimidyl (S-PEG).
2 The structural formula for this compound and the reaction product obtained by reacting it with a 3 glycosarninoglycan derivative such as deacetylated hyaluronic acid is shown in Formula 2. In any 4 general structural forrnula for the compounds, the subscript 3 is replaced with an "n". In the S embodiment shown in Forrnula 1, n=3, in that there are three repeating CH2 groups on either side 6 of the PEG. The structure in Forrnula 2 results in a conjugate which includes an "ether" ;inkage 7 which is not subject to hydrolysis. This is distinct from the conjugate shown in Formula 1, 8 wherein an ester linkage is provided. The ester linkage is subject to hydrolysis under physiological 9 condiDons.

S-PEG, n=3: Difunctionally Activated PEG Succinirnidyl ,, .

C~ N-O-OC-(CH2)3-0-PEG-O-lCH2)3-CO-O-N g~

" GAG-PLYM-NH2 GAG-PLYM-NH2 .' ' ~ ~
' GAG-PIYM-HN-OC-(cH2)3-l ~-PEG-O-(CH2)3-CO-NH-PLYM-GAG

' : ' 12 FORMI~LA2 :: 27 .~ , , . :
: .

''~

. ~ .

~13 !.~ 7 ~

Yet another difimctionally ac~vated forrn of polyethylene glycol, wherein n=2, is shown in 2 Formula 3, as is the conjugat~ formed by reacting the act;vated PEG with a glycosarninoglycan 3 deriva~dve. ~ :

4 .S-PEG, n=2: Difunctionally Activat~d PEG Succir~irr~idyl C~N-O-OC-(CH2)2-O-PEG-O-(CHZ)2-CO-O-N
I
-, GAG-PLYM-NH2 GAG-PLYM-NH2 f GAG-PLYM-HN-OC-(CH2)2-o-PEG-o-~CH2)2-Co-NH-PLYM-GAG

,.1 ,~

-' :
.~ I

2 1 3 ~

Another preferred emb xiiment of the invention similar to ~e compounds of Fonnulas 2 : :
2 and 3 is provided when n=l. The structural formula and resulting conjugate are shown in Fonnula 3 4. It is noted that the conjugate includes both an ether and a pep~de linkage~ These linkages are 4 stable under physiological conditions.

S S-PEG, n=l: Difunctionally Activated PEG Succinirnidyl ~Q 0 L~ N-O-OC-CH2-0-PEG-O-CH I'j O

~ r -~:
GAG-PLYM-HN-OC-CH2-0-PEG-O-CH2-CO-NH-PLYM-GAG ~ , 7 FORMULA 4 ;

I
.' 2~3~7~

Yet another difunctionally activated folm of PEG is provided when n=O. This compound 2 is referred to as PEG succinimidyl carbonate (SC-PEG). The struct~al fonnula of this compound 3 and the conjugate formed by reacting SC-PEG with a glycosarninoglycan derivative is shown in 4 Formula 5.

S SC-PEG7 n=O; Difunctionally Activated PEG Succis~imidyl Çarbonate [~ N-O-OC-O-PEG-O-CO-O-N~

, GAG-PLYM-NH2 GAG-PLYM-NH2 .

GAG-PLYM-HN-OC-O-PEG-O-CO-NH-PLYM-GAG

1 .
,1~ '' ' ,'':
7 .FORMULA S ~ ~

"

.
`
, .~

f ~` ~,-2 1 3 ~ 7 ~ !~

176-~CIP~
All of the derivatives depicted in Forrnulas 1-5 involve the inclusion of the succinimidyl 2 group. How~ver, different activa~ng groups can be attached to one or both ends of the PEG
3 molecule. For exarnple, PEG can be derivatized to form difunctionally activated PEG propion 4 aldehyde (A-PEG), which is shown in Fonnula 6, as is the conjugate formed by the reac~on of 5 A-PEG with a glycosaminoglycan derivative. The linkage shown in Formula 6 is referred to as a 6 -(CH~)n-NH- linkage, where n=1-10.

7 A-PEG~ mctionally Activa~t PEG Propion Aldehyde OHC-ICH2)2^0-PEG-O-(CH2)2-CHO
t i , . ' ',~ .
GAG-PLYM-HN-(CH2)3-0-PEG-O-(CH2~3-NH-PLYM-GAG '. :':

tl g FORMllLA 6 ~, 1. ' ' ~ ' ' I .
. I ,.

.

2 ~ 4 ~

Yet another difunctionally accivated form of polyethylene glycol is PEG glycidyl eeher 2 ~E-PEG), which is shown in Fo~nula 7, as is thc conjugate formed by re~c~ng such with a 3 glycosaminoglycan deriva~ve.

4 . E-PEG: Difunctionally Ac~vated PEG ~Iycidyl Ether / \ / \
CH2-CH-CH2-0-P jG-O-CH2-CH-CH~

GAG-pLyM-NH2 GAG-PLYM-NH2 GAG-PLYM-HN-CH~-CH-CH2-0-PEG-O-CH2-CH-CH2-NH-PLYM-GAG . ;

OH OH :

6 I~ORM111,A7 ' ' ' '.

~ 32 :
.'1 .

:1 .

- 213~7~5 Chernical Deriva~zation of Glvcosaminoglycans 2 To make the glycosaminoglycan-polyrner conjugates of the present invention, the 3 glycosaminoglycan first must be chemically derivatized in a manner that will provide free amino 4 (~ ) groups which are a~ailable for covalent crosslinking with PEG. Chen~ical deriva~zation of S the glycosaminoglycan to provide free arnino groups can be accomplished by either deacetylation 6 of desulfation, both of which may be effected by the addition of a strong base such as sodium 7 hydroxide to the glycosaminoglycan solution.
8 Glycosaminoglycans such as hyaluronic acid, the chondroi~n sulfates, keratan sulfate, 9 keratosulfate, and chitin can be deacetylated (removal of tbe -COCH3 glOUp) to provide free amino groups, as sbown in Reaction Schemes 1 and 2 for hyaluronic acid and chitin~ respectively.

11 :
, :~ 33 ~;

.~
.

`:~

2 1 3 ~ 7 4 ~

Deacetylation of Hyaluronic Acid with ;~aOH

I_ _ _ _' n 2 Deacetylation by basic hydrolysis with NaOH .

,,, ~ ~

'. ' H OH H NH2 i '-- --'n 4 . ReactionScheme 1 '( :
/

.,~

.,~
::

: ~" " ", ~,, ,:, ~ ,, " , , ~

Deacetvlation of Chisin with NaOH

H NH-CO4H3 H NH-CO-C n N-Acetyl~lucosamine N~ lglucosamine 3 Dea~etylation by basic ~ ~ -4 hydrolysis wi~h NaOH
~ r Chitosan I

H NH-CO-CH3 H NH2 n N-Acetyl~lucosamine :. 7(Partially deacetylated chitin~ :
8 or Chito~n2 ~ ' ~ L~
:, H NH2 H NH2 ;~ n .~ 2 (Fully deacetylated chitin) 3 Reaction Scheme 2 - ~.
, :::

' ' :,`"', , ~ . "
.,1 i 36 , - ~ ~ ' . ' ~ '~
. ' ~:

^ 2~3-~7~5 Glycosaminoglycans such as heparin, the chondroitin sulfates, keratan sulfate, and 2 keratosulfate can be desulfated (removal of the -SO3 group) to provide free amino groups, as 3 shown in Reaction Scheme 3.

4 Desulfation of Heparin with NaOH

H NH-SO3- H OSO3- n Sulfated ~lucosamine Sulhted ~lucuronic acid Desulfation by basic 6 hydrolysis withNaOH

H INH2 H OH n ..

8 ~eaction Scheme 3 7 ~ ~

As per Table 1, below, certain glycosaminoglycans, such as the chondroitin sulfates, 2 kera~an sulfate, and keratosulfate contain both -COCH3 and -SO3 groups and are therefore subject 3 to both deacetyla~on and desulfation by the addition of sodium hydroxtde. Oeacetyla~on and 4 desulfation of chondroitin sulfate C is shown in Reaction Scheme 4.

Table 1. ~erivatization of Glvcosamino~elvcans bv Deacetvlation and Desulfation _ - I
Compound Deacetyla~ion_Desulfation Chitin _ _ Yes No Chondroitin sulfale A _ Yes Yes Chond~itin sulfate B Yes _ Yes _ Chondroilin sulfate C Yes Yes Heparin No Yes Hyaluronic acid Yes No Keratan sulfate _ _ Yes Yes _ Keratosulfale Ye~ s Yes 7 Crosslinkin,e of Chemicallv Derivatized GlYco~rr~ino~lYcans with PEG : ~:
8 Glycosaminoglycans that havc been chemically derivatizcd to have &ec amino groups can 9 be crosslinked with activated multifunctional PEG, as shown in Reaction Scherne S for deacetylated hyaluronic acid.

., .

." ' ~
3~

i 213~7~5 Deacetvlation and Desulfation of Chondroitin Sulfate C

COOH CH20SO~H

, '_ I ~ ~H H NHCOCH3 j .

2 Desulfation and deacetylation by 3 basic hydrolysis with NaOH ::
' ,. ' ~
~ r ,~

1 ~ H OH H NH2 ' .

: :;~

.,:
::~ .

'~

2 13 ~ 7~5 I

2 Reaction Scheme 4 3 C~ nk;,ngQf DeaCetVIated HYalU~OniC Acid with 4 Difu,nctionallv Activated S-PE~

S Deace~lation by basic 6 hydrolysis with NaOH

_ ~ r _ ' ,1 OH H NH2 - - n 1l ,', -", C N~C~CH2)n--~PEG~
I~ ~
.~ ;

~ ~7 H~L
H ~ H
H OH H NH
:~ ~~ \ --n OC--(CH2)n{)--PEG~DHA
: DHA=Deacetylat~d Hyaluronic Acid 8 Reaction Scheme 5 1 .
.

,, ,, ~ ~ J `~ 7 ~ .) Glycosaminoglycan-polymer conjugates are formed within minutes of combirung the 2 chemically derivatized glycosaminoglycan and the functionally activated polymer. The 3 glyc~saminoglycan derivative can be rnixed with the polymer using syringe-to-syrLnge rmLxing.
4 Alternatively, the glycosarninoglycan derivative can be extruded into a solution of dle activated S polyrner, crosslinking will occur as the polymer diffuses into the glycosaminoglycan.
The rate of conjugate forrnation and the characteristics of the resulting conjugate can be 7 varied by varying the type of activated PEG used andlor the molecular weight and concentra~ion of 8 the PEG. In general, the use of PEG species (such as S-PEG) which result in ether or urethane 9 linkages lead to the creation of more stable conjugates than those which result in the readily hydrolyzed ester linkages. However, in certain situations, such as drug delivery appLications, it is 11 desirable to include the weaker ester linkages: the linkages are gradually broken by hydrolysis 12 under physiological conditions, breaking apart the matrix and releasing the pharrnaceutically active 13 component held therein. Different species of PEG can be mixed and used in the same drug 14 delivery composition, resulting in a varied rate of matrix degradation and, hence, drug release.
li Multifi~nctionally activated PEG can be used to crossLink more than one species of 16 glycosaminoglycan derivative, or glycosaminbglycan derivatives and collagen, as shown in 17 Reaction Scheme 6 for deacetylated hyaluronic acid and collagen. The resul~ng composite material 18 has different physical and chernical properties than either PEG-crossLinked collagen or PEG-19 crosslinked glycosarninoglycan alone.

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90n NH2 H OH H NH2 l ~ ~-__ __ n ,:~

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The glycosaminoglycan-polyrner-collagen composites can be produced in a nurnber of 2 ways, as described in experimental Examples 3-6.
3 Suitable collagens for use in the invention include all types of collagen; however, types I, 4 II, and m are preferred. The collagen used in the practice of the invention may be either fib~illar S (e.g., Zyderm~ Collagen) or nonfibrillar. Either atelopeptide or telopeptide-containing collagen 6 may be used, depending on the desired end use of the conjugate. Various forms of collagen are 7 available comrnercially, or may be prepared by the processes described in, for èxample, U.S. Pat.
8 Nos. 3,949,073; 4,488,911; 4,424,208; 4,582,640; 4,642,117; 4,557,764; and 4,689,399, all 9 incorporated herein by reference.
Collagen contains a number of available amino and hydroxy groups which may be used to 11 bind the collagen to the glycosaminoglycan-synthetic polyrner conjugate. Methods of conjugating 12 collagen to polyethylene glycol are discussed in detail in U.S. Patent 5,162,430.

13 Use and Ad~Tunistration 14 The primary use of the glycosaminoglycan-synthetic polymer and glycosarninoglycan-synthetic polyrner-collagen conjugates of the invention is as injectable compositions for soft tissue 16 augmentation (such as dennal augmentation or sphincter augrnentation) and drug delivery. For 17 injectable formulations, glycosaminoglycan concentrations within the range of about 10 to about 18 100 mglmL are generally used. The concentra~on of activated synthetic polymer in the 19 composition is preferably ~,vithin the range of about 1 to about 400 milligrams of activated synthetic polymer per millileter of composition.
21 Crosslinking between the glycosaminoglycan and the synthetic polymer can be performed 22 in vitro, or a reaction mixture may be injected for crosslinking in si~u. The glycosaminoglycan 23 derivative and activated polymer can be stored in separate barrels of a double~barreled syringe. As 24 the plunger of the syringe is depressed and the rnaterial is injected beneath the skin, the components mix in the needle of syringe and crosslink in sitlA Some of the activated polymeir 26 molecules may additionally crosslink to the patient's own collagen to anchor the implant in place.
27 Gel formation will occur within twenty minutes or less of adrninistration. Injectable composidons 28 may further be used for hard tissue repair in situations where surgery is not desirable or 29 recomrnended. In hard tissue applications, the injectable cornposition serves as a matrix for regeneration of bone or car~lage at the site of placernent.

~, 21~ i~7~5 176-88CrP8 In ~ddition to aqueous injectable solutions, prepolymerized glycosaminoglycan-polymer 2 conjugates can be dried and then ground into d~ied particulates. Alt~rnatively, glycosam noglycan-3 polymer conjugates can be dried in bead or droplet form. The beads or particles cornprising the 4 conjugates can be suspended in a nonaqueous carrier and injected to a soft tissue site in need of augmentation. Once in situ, the particulates rehydrate and swell three- to five-fold due to the 6 hydrophilicity of the polyethylene glycol molecules. Less volume of product is therefore required 7 to achieve the desired connection.
8 The multifunctionally activated synthetic polymers rnay be used to covalently crosslink 9 glycosaminoglycan derivatives to collagen or to biologically active proteins such as cytokines and growth factors. Such compositions are par~cularly suited for use in wound healing, osteogenesis, 11 and imrnune modulation. Tethering of biologically a~tive molecules to glycosalTunoglycans 12 provides an effective sustained release drug delively system. As described above, different species 13 of polyethylene glycol can be included in the forrnulation to result in varying rates of drug release.
14 Compositions of the invention containing biologically active cytokines or growth factors such as TGF-B are prepared by admixing an appIopriate arnount of the cytokine or growth factor 16 into the composition, or by incorporating the cytokine or growth factor into ~e glycosaminoglycan 17 prior to treatment with activated PEG. Preferably, the cytokine or growth factor is first reacted 18 with a molar excess of a multifunctionally activated polyethylene glycol in a dilute solution for 19 three to four minutes. The cytokine or growth factor is preferably provided at a concentration of about 1 llg/mL to about S mg/mL, while the activated polymer is preferably added to a final concen-21 tration providing a thirty- to f~fty-fold molar excess. The conjugated biologically active factor-22 synthetic polymer is then added to an aqueous glycosalTunoglycan mixture (preferably having a 23 concentradon within the range of about 1 to about 60 mg/mL) at neutral pH (approximately 7 - 8) 24 and allowed to react further to form biologically active factor-synthetic polymer-glycosaminoglycan conjugates. The resulting composidon is allowed to stand overnight at ambient temperature. Thc 26 pellet is collected by centrifugation and washed with PBS, using vigorous vortexing to remove 27 unbound factor.
28 Compositions of thc invaltion containing biologically active factors such as cytokines or 29 growth factors are particularly suited for sustained rdease of factors, as in the case of wound heal-ing promotion. Osteoinductive factors and cofactors (including TGF-B) and bone morphogenic 31 protein ~BMP) may advantageously be incorporated into compositions for bone replacement, ~"

F
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~3'17~5 augmentation, and/or defect repair. Altematively, one may administer antiv*al and anti~umor 2 factors such as TNF, interferons, CSFs, TGF-B, and the like for the* pharrnaceutical activlties.
3 The amount of cytokine or grow~ factor incoIporated into the composition is determined based on 4 the type of factor being used, the severity of the condition being treated, the rate of delivery S des*ed, etcThese parameters may be deterrnined by routine experimentation; for example, by 6 prepaIing a conjugated factor-polymer-glycosarninoglycan composition as described above and 7 assay~ng the release rate of factor in a suitable animal model.
8 Compositions of glycosarninoglycan-synthetie polyrner conjugates can also be forrned into 9 relatively solid implants. Compositions of the invention can be prepared in a form that is dense 10 and rigid enough to substitute for c~lage. These compositions are useful for repairing and sup-11 porting tissues which require some degree of structure and rigidity, for example, in reconstruction 12 of the nose, ear, knee, larynx, tracheal rings, and joint surfaces. One ean also replace tendons, 13 ligaments, and blood vessels using appropriately formed cartilaginoid materials. In these 14 applications, the rnaterial is generally cast or molded into the desired shape. Materials for tendon 15 and ligarnent replacernent may be formed by braiding or weaving filaments of the 16 glycos~ninoglycan - polymer conjugates into cords or ropes. In the case of artificial blood 17 vessels, it may be advar~tageous to incorporate a reinforcing mesh (e.g., nylon, Teflon~, or 18 Dacron~). -19 Forrnulations suitable forrepair of bone defects or nonunions may be prepaIed by 20 providing high concentration compositions of bioeompatible conjugates, such as 21 glyeosaminoglycan-synthetie polymer, glycosaminoglycon-synthetic polymer-collagen; or one of 22 these ~onjugates in combination with a eytokine or growth factor, any of which may be used in 23 admix ure with suitable partieulate materials. When making bone repair eompositions intended to 24 persist for long periods of time invivo, the linkage between the glyeosaminoglycan and synthetic 25 polyrner may be an ether linkage in order to avoid deterioration due to the hydrolysis of the este~
26 linkages. Sueh eonjugate/partieulate eompositions may be malleable or rigid, depending on the 27 amount of liquid ineorporated. Formulations for treatment of stress-bearing bone are preferably 28 dried and rigid, and will generally eomprise be~tween about 45% and 85% particulate rnineral, for 29 example, hydroxyapatite or triealeium phosphate, or mixtures thereof. The tensile strength and 30 rigidity may be further increased by heating the eomposition under vaeuurn at about 60-90-C, 31 preferably about 75 C, for about 5 to 15 hours, preferably about 10 hours.

., '~

2~3 ~7~

Flexible sheeits or membranous forms of glycosa~inoglycan-synthetic polyrner conjugates 2 may be prepared by methods known in the art; for example, U.S. Patent Nos. 4,600,533, 3 4,412,947, and 4,242,291. Briefly, an aqueous solution of glycosaminoglycan having a 4 concentration in the range of approx~mately 10 - 100 mg/rnL is cast into the bottom of a flat container. A solution of activated polyethylene glycol is added to the glycosaminoglycan solution 6 and allowed to react at room temperature for a period of tirne ranging from several hours to over-7 night. The resulting glycosamînoglycan-polymer conjugate is removed from the bottom of the 8 container using a spatula and then washed with PBS to remove excess unreacted polymer.
9 The resulting conjugate composition may be compressed under constant p ressure to form a uniform sheet or mat and optionally dehydrated under a vacuum oven or by Iyophilization or air-11 dIying to form a membrane of the invention. More flexible membranes can be obtained using 12 lower glycosaminoglycan concentrations, higher syn~hetic polymer concentrations, and shorter 13 reaction dmes.
14 Glycosaminoglycan-synthetic polymer conjugates may also be prepared in the forrn of sponges by lyophilizing an aqueous slurry of the composition af~er conjugation.
16 Glycosaminoglycan-synthetic polymer conjugate compositions can be formulated into 17 hydrogels having moisture contents in the range of about 5 to about 95%. By varying the moisture 18 content, hydrogels of varying density and stiffness may be obtained, depending on the desired end 19 use application.
. Glycosaminoglycan-synthetic polymer conjugates can be used to coat breast implants. The 21 surface of a standard silicone shell irnplant can be chemically derivatized to provide active binding 22 sites for di- or multifunctionally activated PEG-glycosarninoglycan (glycosaminoglycan-PEG-23 silicone). The presence of the conjugate coating bound directly to the silicone via activatcd PEG
24 will reduce scar tissue formation and capsular contracture. Unlike typical coated irnplants, scar tissue will not be able to grow between the coating and the implant because the coating is 26 conjugated directly to the su~face of the implant 27 Alternatively, a flexible sheet of glycosaminoglycan-synthetic polymer conjugate 1l 28 formulation can be formed into a hollow sphere for use as a breast implant sheLh The shell can ;i 29 then be filled with a radiolucent material, such as a triglyceride, to facilitate mammography.

;l .J
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,i -. ~: -,. ,; .: i,.:.. ,.. ,,.. .. , . : .: . .

7 ~ 5 Formulations of glycosarninoglycan-synthetic polymer conjugates may also be used to coat 2 other types of implants for long-term use in the body, such as catheters, cannulas, bone pros-3 theses, cartilage replacements, rninipumps and other drug delivery devices, artificial organs and 4 blood vessels, meshes for tissue reinforcement, etcGlycosaminoglycan-synthetic polymer S compositions can also be used to coat platinum wires, which can then be administered to the site of 6 an aneurysm via catheter. Such surface treatment renders the implants nonimmunogenic and 7 reduces the incidence of foreign body reaction.
8 Coating of an implant with a conjugate composition may be accomplished by dipping the 9 irnplant into a solution containing glycosaminoglycan and synthetic polymer while crosslinking is occurring and allowing the adherent viscous coating to dry as crosslinking is completed. One rnay 11 pour, brush, or otherwise apply the reaction rnixture to the implant if dipping is not feasible.
12 Alternatively, one may use flexible sheets or membranous forms of the conjugate to wrap the 13 object, sealing corners and edges with reaction mixture.

The foilowing examples are set forth so as to provide those of ordinary skill in the art with 16 a complete disclosure and description of how to make the conjugates and formulations and 17 implants containing such conjugates and are not intended to lirnit the scope of the invention.
18 Efforts have been made to ensure accuracy with respect to mJmbers used (e.g., amounts, 19 temperature, molecular weight, etc.), but some experimental errors and deviation should be accounted for. Unless indicated otherwise, parts are parts by weight, molecular weight is average 21 molecular weight, temperature is in degrees Centigrade, and pressure is at or near atmospheric.

22 Bxample I
23 One (I) gram of sodium hyaluronate (obtained from LifeCore Biomedical) was added to 15 24 ml of 0.2M NaOH and allowed to dissolve overnight to form a homogeneous solution. Five (5) ml of the hyaluronic acid that was neutralized with lM HCI solution was rmixed with 50 mg of 26 difunctionally activated S-PEG in 0.5 ml of PBS using syringe-to-syringe mixing.
27 The resulting material was extruded from the syringe into a petri dish and incubated at 28 37C. Af~er 16 hours, the material had formed a crosslinked gel.

~ 47 ~ ' ~ ~ : ' ` ~13~745 Hyaluronic acid without S-PEG was used as a control in this experiment. After 1 6-hour 2 incubation, the control was still liquid and ruMy.

3 Exarnple 2 4 Forty (40) mg of difunctionally activated S-PEG was nuxed with 145 ul of 1 M HCl.
After thorough rnixing, the acidified S-PEG solution was drawn ir to a syringe.
6 A 6.6% (w/v) solution of deacetylated hyaluronic acid was prepared by rnixing hyaluronic 7 acid with 0.2 M NaOH. The deacetylated hyaluronic acid solution (pH 13) was also transferred to 8 a syringe.
9 The two syringes were then cormected with a 3-way stopcock and the contents mixed using 10 , syringe-to-syringe mixing. Mixing the acidified S-PEG with the deacetylated hyaluronic acid 11 caused the pH of the solution to neutralize and the crosslinking reaction to occur.
12 After mixing for 60-70 passes, the material was transferred to one syringe. The stopcock 13 and the second (empty) syringe were remov~d. The material was now ready for injection and in 14 situ crosslinking.

Exarnple 3 16 One (1) milliliter of 35 mg/ml collagen in solution (pH 2) is mixed with 1 ml of a 2% (wlv) 17 acidified solution of difunctionally activated S-PEG. The S-PEG - collagen solution is 18 imrnediately mixed with 2 ml of a 10 mg/ml solution of deacetylated hyaluronic acid (pH 13), 19 neutralizing the pH of the mixture and causing the difunctionally activated S-PEG to covalently bond with both the collagen and the hyaluronic acid.

21 ~B~21Q~L
22 One (1) milliliter of 35 mg/ml Zyderrn~9 I Collagen and 1 ml of a 10 mg/rnl solution of 23 hyaluronic acid are mixed together at pH 10. The collagen-hyaluronic acid solution is then mixed 24 with 2 ml of a 2% (w/v) solution of difunctionally activated S-PEG in 0.1 M HCI (pH 1), causing the solution to neutralize and crosslinking to occur between PEG, collagen, and hyaluronic acid.
,, ~1 ,. .-, ' :''~
l :' 2~3 ~745 Example 5 2 One (1) rnilliliter of 35 mg/ml Zyderrnt~ I Collagen (pH 7) is mixed with 1 rnl of a 10 3 mg/ml solu~ion of deacetylated hyaluronic acid in 0.2 M NaOH (pH 13). Two (2) rnilliliters of a 4 4% (wh~ solution of acidified difunctionally activated S-PEG is imrnediately added to neu~alize the pH and effect crosslinking between the ~ree components.

6 Example 6 8 One (1) rnilliliter of Zyderm(~ I Collagen and 1 ml of a 10 mg/mo solution of deacetylated 9 hyaluronic acid are each adjusted to pH 9, then mixed together. The collagen-hyaluronic acid solution is then adjusted to approximately pH 7 by adding 0.1 M HCI, causing the hyaluroluc acid 11 and collagen to form a weak gel due to ionic interaction. Subsequent addition of difunctionally 12 activated S-PEG results in covalent crosslinking, producing a strong gel.
13 Example 7 14 . (Coating of Lrnplants) Prepare a hyaluronic acid - S-PEG reaction mixture as described in Example 1. Dip a 16 titaniurn irnplant into the reaction mixture irnrnediately after crosslinking is ini~ated. Allow the 17 i nplant coating to finish crosslinking, and dry overnight.

18 The present invention is shown and described herein at what is considered to be the most 19 practical and preferred embodiments. lt is recognized, however, that departures may be made therefrom which are within the scope of the invcntion and that obvious modifications will occur to 21 one sldlled in the art upon reading thi, disclosure. ~

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Claims (50)

1. A biocompatible, biologically inert conjugate comprising a glycosaminoglycan or derivative thereof chemically conjugated to a hydrophilic synthetic polymer.

2. The conjugate of claim 1, wherein the glycosaminoglycan is selected from the group consisting of hyaluronic acid, chondroitin sulfate A, chondroitin sulfate C, dermatan sulfate, heparin, keratan sulfate, keratosulfate, chitin, chitosan 1, chitosan 2, and derivatives thereof.

3. The conjugate of claim 1, wherein the glycosaminoglycan is derivatized by deacetylation or desulfation.

4. The conjugate of claim 1, wherein the synthetic hydrophilic polymer is a multifunctionally activated polyethylene glycol.

5. The conjugate of claim 4, wherein the synthetic hydrophilic polymer is a difunctionally activated polyethylene glycol.

6. The conjugate of claim 1, wherein the conjugate has the following general structural formula:

GAG-HN-OC-(CH2)n-Z-PEG-Z-(CH2)n-CO-NH-GAG

wherein n is an integer ranging from 0 to about 4, GAG is a glycosaminoglycan or a derivative thereof, and Z is O or O-C=O.

7. The conjugate of claim 1, wherein the conjugate has the following structural formula:

GAG-HN-OC-(CH2)n-Z-PEG-Z-(CH2)n-CO-NH-GAG' wherein n is an integer ranging from 0 to about 4, GAG is a species of glycosaminoglycan or a derivative thereof, GAG' is a different species of glycosaminoglycan or a derivative thereof, and Z is O or O-C=O.

8. The conjugate of claim 7 or claim 8, wherein GAG and GAG' are selected from the group consisting of hyaluronic acid, chondroitin sulfate, chondroitin sulfate C, dermatan sulfate, heparin, keratan sulfate, keratosulfate, chitin, chitosan 1, chitosan 2, and derivatives thereof.

9. The conjugate of claim 1, in the form of a hydrogel composition having a moisture content in the range of from about 5% to about 95%.

10. A composition comprising:
a conjugate comprising a glycosaminoglycan or a derivative thereof chemically conjugated to a hydrophilic synthetic polymer; and a therapeutically effective amount of a cytokine or growth factor.

11. The composition of claim 10, wherein the glycosaminoglycan is selected from the group consisting of hyaluronic acid, chondroitin sulfate A, chondroitin sulfate C, dermatan sulfate, heparin, keratan sulfate, keratosulfate, chitin, chitosan 1, chitosan 2, and derivatives thereof, and mixtures of these glycosaminoglycans or their derivatives.

12. The composition of claim 10, wherein said cytokine or growth factor is selected from the group consisting of epidermal growth factor, transforming growth factor-a, transforming growth factor-.beta., transforming growth factor-.beta.2, platelet-derived growth factor-AA, platelet derived growth factor-AB, platelet-derived growth factor-BB, acidic fibroblast growth factor, basic fibroblast growth factor, connective tissue activating peptide, .beta.-thromboglobulin, insulin-like growth factors, tumor necrosis factor, interleukins, colony stimulating factors, erythropoietin, nerve growth factor, interferons, bone morphogenic protein and osteogenic factors.

13. The composition of claim 12, wherein the growth factor is selected from thegroup consisting of transforming growth factor-.beta., transforming growth factor-.beta.1, transforming growth factor-.beta.2, and erythropoietin.

14. An injectable, pharmaceutically acceptable composition comprising:
a conjugate comprised of a glycosaminoglycan or a derivative thereof chemically conjugated to a hydrophilic synthetic polymer; and a sufficient amount of a fluid pharmaceutically acceptable carrier to render thecomposition injectable.

15. The conjugate of claim 14, wherein the glycosaminoglycan is selected from the group consisting of hyaluronic acid, chondroitin sulfate A, chondroitin sulfate C, dermatan sulfate, heparin, keratan sulfate, keratosulfate, chitin, chitosan 1, chitosan 2, and derivatives thereof, and mixtures of these glycosaminoglycans or their derivatives.

16. A biocompatible, biologically inert conjugate comprising a difunctionally activated hydrophilic synthetic polymer chemically conjugated to both collagen, or a derivative thereof, and to a glycosaminoglycan, or a derivative thereof.

17. The conjugate of claim 16, wherein the conjugate has the following structural formula:

GAG-HN-OC-(CH2)n-Z-PEG-Z-(CH2)n-CO-NH-COL

wherein n is an integer ranging from 0 to about 4 and GAG is a glycosaminoglycan or a derivative thereof; COL is collagen, or a derivative thereof; and Z is O or O-C=O.

18. The conjugate of claim 17, wherein the glycosaminoglycan is selected from the group consisting of hyaluronic acid, the chondroitin sulfates, heparin, keratan sulfate, keratosulfate, chitin, chitosan 1, chitosan 2, and derivatives thereof, and mixtures of these glycosaminoglycans or their derivatives.

19. The conjugate of claim 17, wherein the collagen is selected from the group consisting of fibrillar collagen or nonfibrillar collagen.

20. The conjugate of claim 17, in a form selected from the group consisting of amembrane, bead, sponge, tube, sheet, and formed implant.

21. The conjugate of claim 17, in the form of a hydrogel composition having a moisture content in the range of from about 5% to about 95%.

22. The conjugate of claim 20, in the form of a formed implant for use in the repair, augmentation, or replacement of a body part selected from the group consisting of a heart valve, patella, ear, nose, and cheekbone.

23. The conjugate of claim 17, in the form of a bodily fluid replacement for joint fluid or vitreous humor.

24. A composition suitable for coating an implant, comprising a conjugate including a difunctionally activated hydrophilic synthetic polymer chemically conjugated to at least one species of glycosaminoglycan or derivative thereof.

25. The composition of claim 24, wherein the conjugate comprises a difunctionally activated hydrophilic synthetic polymer chemically conjugated to one species of glycosaminoglycan or a derivative thereof, and to collagen or a derivative thereof.

26. The composition of claim 24, wherein the conjugate comprises a difunctionally activated hydrophilic synthetic polymer chemically conjugated to two different species of glycosaminoglycans or derivatives thereof.

27. The composition of claim 24, wherein the conjugate comprises a difunctionally activated hydrophilic synthetic polymer chemically conjugated to one species of glycosaminoglycan or a derivative thereof.

28. The composition of claim 24, wherein the glycosaminoglycan is selected from the group consisting of hyaluronic acid, chondroitin sulfate A, chondroitin sulfate C, dermatan sulfate, heparin, keratan sulfate, keratosulfate, chitin, chitosan 1, chitosan 2, and derivatives thereof, and mixtures of these glycosaminoglycans or their derivatives.

29. The method of claim 25, wherein the collagen is selected from the group consisting of fibrillar collagen and nonfibrillar collagen.

30. A composition suitable for augmentation of hard tissue in a mammal, comprising a biocompatible, biologically inert conjugate comprising a difunctionally activated hydrophilic synthetic polymer chemically conjugated to at least one species of glycosaminoglycan or derivative thereof, wherein the conjugate has been dehydrated to remove substantially all unbound water.

31. The composition of claim 30, wherein the conjugate comprises a difunctionally activated hydrophilic synthetic polymer chemically conjugated to one species of glycosaminoglycan or a derivative thereof, and to collagen or a derivative thereof.

32. The composition of claim 30, wherein the conjugate comprises a difunctionally activated hydrophilic synthetic polymer chemically conjugated to two different species of glycosaminoglycans or derivatives thereof.

33. The composition of claim 30, wherein the conjugate comprises a difunctionally activated hydrophilic synthetic polymer chemically conjugated to one species of glycosaminoglycan or a derivative thereof.

34. The composition of claim 30, wherein the glycosaminoglycans are covalently bound to the hydrophilic synthetic polymer via a linkage selected from the group consisting of an ester linkage, an ether linkage, a urethane linkage, and a -(CH2)n-NH- linkage.

35. The method of claim 30, wherein the glycosaminoglycan is selected from the group consisting of hyaluronic acid, chondroitin sulfate A, chondroitin sulfate C, dermatan sulfate, heparin, keratan sulfate, keratosulfate, chitin, chitosan 1, chitosan 2, and derivatives thereof, and mixtures of these glycosaminoglycans or their derivatives.

36. The method of claim 31, wherein the collagen is selected from the group consisting of fibrillar collagen or nonfibrillar collagen.

37. A method for preparing a glycosaminoglycan-polymer conjugate suitable for administration to mammals, comprising the steps of:
providing an aqueous solution of chemically derivatized glycosaminoglycan;
adding a solution of an activated synthetic polymer to form a reaction mixture, wherein said activated polymer comprises a hydrophilic synthetic polymer having a reactive group capable of forming a covalent bond with an available amino group on the chemically derivatized glycosaminoglycan; and causing said polymer to form covalent bonds with the glycosaminoglycan.

38. A method for augmenting soft tissue in a mammal, comprising the steps of:
preparing an injectable composition by mixing together at least one species of glycosaminoglycan derivative and a difunctionally activated hydrophilic synthetic polymer;
injecting the composition into a soft tissue site in need of augmentation immediately following mixing so as to allow the chemical conjugation of the glycosaminoglycan polymer and collagen to continue in situ following injection.

39. The method of claim 38, wherein the injectable composition comprises at least one species of glycosaminoglycan or a derivative thereof.

40. The method of claim 39, wherein the injectable composition further comprisescollagen or a derivative thereof.

41. The method of claim 38, wherein the injectable composition comprises two species of glycosaminoglycans or derivatives thereof.

42. The method of claim 38, wherein the glycosaminoglycan is selected from the group consisting of hyaluronic acid, chondroitin sulfate A, chondroitin sulfate C, dermatan sulfate, heparin, keratan sulfate, keratosulfate, chitin, chitosan 1, chitosan 2, and derivatives thereof, and mixtures of these glycosaminoglycans or their derivatives.

43. The method of claim 40, wherein the collagen is selected from the group consisting of fibrillar collagen and nonfibrillar collagen.

44. A method for augmenting hard tissue in a mammal comprising: applying, by injection or surgical implantation, to a hard tissue site in need of augmentation, a composition comprising a biocompatible, biologically inert conjugate comprising a difunctionally activated hydrophilic synthetic polymer chemically conjugated to at least one species of glycosaminoglycan or derivative thereof, wherein the conjugate has been dehydrated to remove substantially all unbound water.

45. The method of claim 44, wherein the injectable composition comprises one species of glycosaminoglycan or derivative thereof.

46. The method of claim 45, wherein the injectable composition further comprisescollagen or a derivative thereof.

47. The method of claim 44, wherein the injectable composition comprises two species of glycosaminoglycans or derivatives thereof.

48. The method of claim 44, wherein the glycosaminoglycan is selected from the group consisting of hyaluronic acid, chondroitin sulfate A, chondroitin sulfate C, dermatan sulfate, heparin, keratan sulfate, keratosulfate, chitin, chitosan 1, chitosan 2, and derivatives thereof, and mixtures of these glycosaminoglycans or their derivatives.

49. The method of claim 42, wherein the collagen is selected from the group consisting of fibrillar collagen or nonfibrillar collagen.

50. The method of claim 44, wherein the hard tissue site is selected from the group consisting of bone and cartilage.