EP1335759A1

EP1335759A1 - Porous polymeric biomaterials, preparation method and uses

Info

Publication number: EP1335759A1
Application number: EP01997318A
Authority: EP
Inventors: Vincent Boudy; Alexandre Laurent; Denis Labarre; Jean-Claude Chaumeil
Original assignee: Assistance Publique Hopitaux de Paris APHP
Current assignee: Assistance Publique Hopitaux de Paris APHP
Priority date: 2000-11-22
Filing date: 2001-11-19
Publication date: 2003-08-20
Also published as: AU2002220795A1; FR2816847A1; FR2816847B1; US20040071776A1; CA2432804A1; IL156050A0; WO2002041928A1

Abstract

The invention concerns porous polymeric biomaterials containing a porous polymeric matrix optionally filled with biological and/or chemical active agents, the method for preparing same and their uses, in particular as implant.

Description

POROUS POLYMERIC BIOMATERIALS, METHOD OF PREPARATION AND USES

The present invention relates to porous polymer biomaterials containing a porous polymer matrix possibly loaded with biological and / or chemical active agents, their preparation process and their uses, in particular as an implant.

The use of absorbable or non-absorbable biomaterials is frequent in the medical environment. These biomaterials can come in various forms and can be used, for example, for the production of therapeutic vascular occlusions (embolizations), for cell reconstruction, the treatment of gastroesophageal reflux, urinary incontinence or even for the reduction of wrinkles.

Thus, for the production of therapeutic vascular occlusions, it has already been proposed, in particular in patent application FR-A-2 676 927, the use of microbeads composed of a hydrophilic acrylic copolymer covered with a agent promoting cell adhesion such as for example collagen, gelatin, glucosaminoglycans, fibronectin, lectins, etc. The acrylic copolymer composing these microbeads preferably contains one or more monomers carrying a cationic charge, so as to initiate and improve cell adhesion to the microbeads at the embolization site. Furthermore, during the synthesis of these microbeads, and in order to increase their stability, a crosslinking agent can be added to crosslink the adhesion agent covering the microspheres.

Still for embolization, it has also been proposed, in particular in patent application FR-A-2 784 580, microspheres comprising crosslinked polyvinyl alcohol, said microspheres also being able to comprise an agent promoting adhesion cell and possibly be impregnated with an active ingredient such as an anti-angiogenic or anti-inflammatory agent. However, with this type of microspheres, it is not possible to control the release of the incorporated active principle, that is to say the delayed or prolonged release thereof. On the other hand, international application WO 99/44643 describes a method of treatment of gastroesophageal reflux in which are used biocompatible cationic hydrophilic microparticles comprising an agent promoting cell adhesion and possibly an active principle carrying an anionic charge capable to bind covalently to said cationic microparticles. However, the use of this type of microparticles is limited to the incorporation of active principles having an anionic charge and also does not make it possible to control their release.

Finally, it has also already been proposed to coat cationic embolization microspheres onto which was grafted an anionic active principle (indomethacin), the coating of these microspheres being carried out by means of a coating polymer such as ethylcellulose (Boudy et al, J. Pharm. Clin., 1999, 18, 21-23).

However, this technique results in a modification of the physico-chemical properties of the microspheres (shape, mechanical properties, surface of exchange between the biomaterial and the biological medium, etc.) and does not make it possible to achieve a controlled release of the active principle, l coating having no significant action on the release kinetics thereof.

However, the problem of controlling the release of biological and / or chemical assets from a biomaterial is fundamental, insofar as these assets must be able to be retained by the biomaterial for a time suitable for the implantation of said material on the site where the subsequent release of the active ingredient is planned.

For example, in the context of embolizations using microspheres, the active principle, which can in particular be an anti-inflammatory agent, must be able to remain in the microspheres for the entire duration of preparation of the injectable solution containing the microspheres and which will be used to carry out the embolization, then during the routing of these microspheres by the blood circulation to the embolization site where it will finally be released (this duration being approximately 2 to 10 minutes). It is in order to remedy these problems that the inventors have developed what is the subject of the invention. The inventors have therefore set themselves the objective of providing a biomaterial allowing the controlled release (in time and in quantity) of one or more biological and / or chemical active agents.

The present invention therefore relates to a porous biomaterial characterized in that it consists of a porous hydrophilic or amphiphilic polymer network (support network), the pores of which contain a gelled porous polymer network (filling network), and in which the pore diameter of the support network is greater than the pore diameter of the filling network.

The inventors have in fact demonstrated that the presence of a filling network as defined above (in which the biological and / or chemical active ingredient will be contained) within a support network makes it possible to control the release (delayed release or prolonged) of said active ingredient, without, however, modifying the physico-chemical characteristics of the support network (shape, mechanical properties, exchange surface between the biomaterial and the biological medium, etc.). According to an advantageous embodiment of the invention, the hardness of the support network is greater than the hardness of the filling network, because the support network has a solidity ensured by covalent bonds, while the filling network has a solidity ensured by ionic interaction.

According to the invention, the support network can consist of one or more resorbable or non-resorbable polymers.

Among the polymers which can be used as a support network, mention may especially be made of caprolactone polyepsilons, polymers and copolymers of lactic and glycolic acid, albumin, casein, crosslinked gelatins, polyanhydrides, cellulose esters and ethers, acrylic and methacrylic polymers such as acrylates and methacrylates such as for example polyhydroxyethylmethacrylate and its derivatives, substituted or unsubstituted polyacrylamides such as poly- (N-acryloyl-2-amino-2-hydroxymethyl-1,3-propanediol ) and its derivatives (TRISACRYL ®), poly- (n-2-hydroxypropyl methacrylamide) and its derivatives, poly (vinyl alcohols) and polyurethanes Among the acrylic polymers, mention may especially be made of polymers formed from acrylic copolymers modified or not by ionized or ionizable functional groups such as groups (Cj-C) alkylamino and (Cι-C) alkylamino (Cι-C ₄ ) alkyl such as for example the diethylaminoethyl group (DEAE).

Preferably, the support network of the biomaterial according to the invention is a porous microsphere formed of acrylic copolymers modified by DEAE groups. Such microspheres are for example sold under the trade name DEAE-TRISACRYL® by the company BIOSEPRA.

According to the invention, the filling network can consist of one or more resorbable polymers or not.

Among the polymers which can be used as a filling network, there may be mentioned in particular alginates, pectins, hyaluronic acid, carrageenans, agarose, agaropectins, amyloses, amylopectins, arabino-galactans, cellulose and its derivatives such as for example methylcellulose and ethylcellulose, chitosan, tragacanth, gum arabic, guar gum, xanthans, dextrans, collagen and gelatins. Cleverly and according to a particular embodiment of the invention, the nature of the polymers which can be used as a filling network can be chosen specifically according to the nature of the enzymes possibly present on the site of implantation of the biomaterial, so that these degrade the filling network in order to free up the assets. By way of example, the polymers of the filling network can therefore also be chosen from azo-linked polymers which will be degraded by azoreductases of bacterial origin, the glucosidic polymers which will be degraded by digestive glucosidases, the mixed acrylic polymers- azo or acrylic-glucosidic or polymers comprising ester bonds which will be degraded by digestive esterases.

According to a preferred embodiment of the invention, the filling network is in the form of an alginate gel.

Alginates are composed of linear sequences of homopolysaccharides composed of α- 1, 4-D-guluronane units and of β-l, 4-D-mannuronane units and linear sequences of heteropolysaccharides composed of linked units in positions 1,4 of α-L-guluronic and β-D-mannuronic acids (Ullmann's Encyclopedia of Industrial Chemistry, 1998, 25, 34-40). The properties of alginates are essentially determined by their molecular mass as well as by the respective proportions of the various saccharide units composing them, these proportions varying according to the species of brown algae from which they are extracted. The hardest gels are obtained from alginates containing a high proportion of α-L-guluronic acid units.

According to the invention, it is preferred to use alginates comprising from 30% to 75% of α-L-guluronic acid units.

Among these alginate gels which can be used as a filling network, mention may especially be made of high viscosity sodium alginate gels such as those sold under the names MANUGEL® DJX, MANUGEL® DMB and KELTONE® HVCR by the company MONSANTO .

As indicated above, the diameter of the pores of the support network is greater than the diameter of the pores of the filling network.

The diameter of the pores of the filling network is preferably such that it allows the diffusion of molecules whose molecular mass varies between 10 daltons (Da) and 10 ⁶ Da approximately and even more particularly between 10 ² and 10 Da.

According to a preferred embodiment of the invention, the filling network of the biomaterial contains at least one biological and / or chemical active.

The nature of the biological and / or chemical active agent (s) that may be contained in the pores of the filling network will vary depending on the applications envisaged and the size of the pores of the filling network.

By way of example, mention may in particular be made of anti-inflammatory agents, angiogenic agents, anti-mitotics, angiogenesis inhibitors, growth factors, vitamins, hormones, proteins, vaccines, peptides, antiseptics, antimicrobials such as antibiotics, and in general any agent for therapeutic, preventive or diagnostic purposes.

The biomaterial according to the invention can be in various forms depending on the applications envisaged. It can in particular be in the form of film, block, sheet, rod, wire, particle such as for example a microsphere, or in any other form suitable for its use in the biomedical field, in particular as an implant. . According to a particularly advantageous embodiment of the invention, the biomaterial according to the invention is a porous microsphere consisting of acrylic copolymers modified or not by ionized or ionizable functional groups chosen from (Cj-C) alkylamino and (Cj -C4) alkylamino (Cj-C) alkyl, the pores of said microsphere being filled with a porous alginate gel, the pores of which contain at least one biological and / or chemical active.

The invention also relates to a process for the preparation of such a biomaterial as defined above, characterized in that it comprises the following stages: a) the impregnation of at least one porous hydrophilic or amphiphilic polymer (support network ) with an aqueous solution (A) of at least one filler polymer in the liquid state, b) impregnation of said porous hydrophilic or amphiphilic polymer with an aqueous solution (B) of at least one agent capable of passing said polymer for filling from the liquid state to the gelled state, and optionally c) the impregnation of said porous hydrophilic or amphiphilic polymer with a composition (C) containing at least one biological and / or chemical active agent, said impregnation being able to be carried out concomitantly in steps a) and b) by addition of composition (C) in one and / or the other of solutions (A) and (B) or separately after steps a) and b).

According to an advantageous embodiment of the method according to the invention, the support network is, in a first step, impregnated by means of a solution (A) as defined above, then in a second step, with a solution (B) as also defined above, the composition (C) being added to the solution (A) and / or (B).

The concentration of filler polymer in the solution (A) preferably varies from 0.01 to 2% by weight relative to the total weight of the solution (A); this concentration can be gradually increased during the duration of operation a). According to this process, the filling polymer is preferably chosen from collagen, gelatins and polysaccharides such as alginates, pectins, dextrans, and carrageenans.

The nature of the agent capable of passing the filling polymer from a liquid state to a gelled state (gelling agent) is of course a function of the nature of the filling polymer.

By way of example, and when the filling polymer is an alginate, the gelling agent is preferably chosen by multivalent ions such as calcium ions. The amount of gelling agent will also vary depending on the amount of filling polymer in the liquid state which it is desired to gel and also according to the hardness of the gel which it is desired to obtain.

This amount of gelling agent is preferably between 10% and 80% by weight relative to the weight of the filling polymer to be gelled.

The impregnation steps can optionally be carried out with stirring, at a stirring speed preferably of between 150 and 2000 revolutions per minute.

It is also possible to sonicate the solutions during the impregnation steps.

On the other hand, it is possible to add one or more surfactants in the aqueous solutions (a) and / or (b), as well as in the composition (C) in order to increase the wettability of the porous hydrophilic or amphiphilic polymer and thus facilitate the impregnation thereof by the filler polymer. These surfactants can be chosen from anionic, cationic, nonionic and amphoteric surfactants, nonionic surfactants being particularly preferred.

The temperature at which the impregnation operations are carried out generally varies from approximately 20 ° C. to 90 ° C.

The duration of each of the impregnation operations is variable and is preferably between 1 minute and approximately 24 hours.

More particularly, step a) is preferably carried out for a period of between 1 and 24 hours; step b) is preferably carried out during a period of between 2 and 24 hours and step c), when carried out separately from steps a) and b) is preferably carried out for a period of between 12 and 48 hours.

Between each impregnation step, the support network can optionally be rinsed, preferably with water.

When the preparation of the biomaterial is complete, it is recovered and dried according to conventional separation and drying techniques (filtration, sieving, etc.; air drying optionally on a fluidized bed, lyophilization, infrared radiation, etc.). The biomaterial loaded or not with biological and / or chemical active agents thus obtained can be in various forms corresponding to the form of the starting hydrophilic or amphiphilic porous polymer (beads, microspheres, sheets, rods, films, etc.) and can be used, in particular in the biomedical field, as an implant (biomaterial not loaded with active) or device for the controlled release of at least one biological and / or chemical active.

By way of example, this biomaterial can in particular be used for the manufacture of vaccination, embolization, tissue reconstruction devices, bioactive implants, etc.

It can also be used for the manufacture of medical devices or of compositions, in particular of pharmaceutical, cosmetic, dermatological, dietetic or veterinary compositions.

In particular, the biomaterial according to the invention can advantageously be used for the preparation of injectable solutions for intra-tissue or intra-vascular implantation. The present invention therefore also relates to an injectable solution for intra-tissue or intravascular implantation, characterized in that it contains at least one biomaterial as defined above.

When said biomaterial is in the form of microspheres, it can in particular be used for the preparation of injectable solution for the production of embolizations.

Preferably, this injectable solution contains porous microspheres consisting of acrylic copolymers modified or not by groups ionized or ionizable functional groups chosen from (Cι-C ₄ ) alkylamino and (Cι-C ₄ ) alkylamino (Cι-C ₄ ) alkyl such as diethylaminoethyl groups, the pores of said microsphere being filled with a porous alginate gel ( embolization microspheres) whose pores optionally contain at least one biological and / or chemical active ingredient. In addition to the foregoing arrangements, the invention also comprises other arrangements which will emerge from the description which follows, which refers to two examples of the preparation of biomaterials in accordance with the invention, and to a comparative study of the release kinetics an active ingredient (indomethacin).

It should be understood, however, that these examples are given solely by way of illustration of the subject of the invention, of which they do not in any way constitute a limitation.

EXAMPLE 1 PREPARATION OF POROUS BIOMATERIALS CONTAINING A POROUS FILLING NETWORK

Acrylic microspheres sold under the name DEAE-TRIS ACRYL ® by the company Biosepra were rinsed with distilled water and then wrung by filtration of the solution of microspheres on a nylon filter of 80 μm using a vacuum pump .

The microspheres thus wrung were then treated according to the conditions appearing in Table I below. In general, 1 g of microspheres, optionally previously dried under infrared radiation at 100 ° C for 10 min, were put to soak in a first alginate solution (MANUGEL ® DMB, MANUGEL ® DJX or KELTONE ® HVCR) initial alginate concentration [Cl], for 1 hour, with or without agitation or sonication. The microspheres were then allowed to soak in a second solution of the same alginate of final alginate concentration [C2] for 24 hours without stirring.

The microspheres were then drained as above and then redispersed in water with stirring at 600 revolutions per minute, then a solution of calcium ions was added. The whole was subjected to flash agitation for a few seconds and then was kept under agitation at 200 rpm for 1 h 30 min.

DEAE-TRISACRYL® microspheres were obtained, filled with a gelled porous filling network (microspheres A to K of Table I below). TABLE I

EXAMPLE 2 PREPARATION OF BIOMATERIALS LOADED WITH INDOMETACIN

The microspheres A to K obtained above in Example 1 were then impregnated by immersion in a solution of indomethacin at 5 g / l for 12 to 48 hours, to obtain microspheres loaded with indomethacin.

EXAMPLE 3 COMPARATIVE STUDY OF THE KINETICS OF INDOMETACIN RELEASE

The H, I, J and K microspheres in accordance with the invention, loaded with indomethacin and as prepared above in Example 2 were used in this study, as well as DEAE-TRIS ACRYL® M microspheres having simply underwent an impregnation step in a 5 g / l indomethacin solution, under the conditions described above in Example 2 (control microspheres: MT).

Control microspheres differ from microspheres in accordance with the invention in that indomethacin is directly contained in the pores of the support network instead of being contained in the pores of the filling network (alginate gel).

The kinetics of indomethacin release were studied and compared for each of these microspheres. This test was carried out according to the standards of the European Pharmacopoeia πi ^th edition (dissolution test in an apparatus with rotating vanes), under conditions such that the indomethacin released in solution does not prevent the release of the indomethacin still contained in the microspheres.

To do this, 1 g of microspheres was suspended in 800 ml of a physiological 0.9% NaCl solution with stirring. Samples were taken at regular intervals, in order to carry out an assay by UV spectrophotometry of the released indomethacin.

The results obtained are shown in Table II below, the amount of indomethacin released being expressed as a percentage of the total amount of indomethacin contained at t ₀ in the microsphere: TABLE II

These results show that the microspheres H to K in accordance with the invention make it possible to delay the release of indomethacin relative to the control microspheres. On the other hand, these results show that by varying the operating conditions for the preparation of these microspheres (nature and concentration of the alginate, concentration of calcium ions), the kinetics of indomethacin release can be varied and thus control his release.

Claims

1. Porous biomaterial characterized in that it consists of a hydrophilic or amphiphilic porous polymer network (support network), the pores of which contain a gelled porous polymer network (filling network), and in which the diameter of the pores of the support network is greater than the diameter of the pores of the filling network.

2. Biomaterial according to claim 1, characterized in that the hardness of the support network is greater than the hardness of the filling network.

3. Biomaterial according to claim 1 or 2, characterized in that the support network consists of one or more resorbable or non-resorbable polymers.

4. Biomaterial according to claim 3, characterized in that the polymers which can be used as a support network are chosen from polyepsilons caprolactones, polymers and copolymers of lactic and glycolic acid, albumin, casein, crosslinked gelatins, polyanhydrides, cellulose esters and ethers, acrylic and methacrylic polymers, substituted or unsubstituted polyacrylamides, poly (vinyl alcohols) and polyurethanes

5. Biomaterial according to claim 4, characterized in that the acrylic polymers are chosen from those formed from acrylic copolymers modified or not by ionized or ionizable functional groups chosen from the groups (Cj-C ₄ ) alkylamino and (Cι-C ) alkylamino (Cι-C ₄ ) alkyl.

6. Biomaterial according to claim 5, characterized in that the functional groups are diethylaminoethyl groups.

7. Biomaterial according to claim 6, characterized in that said support network is in the form of a porous microsphere formed of acrylic copolymers modified by diethylaminoethyl groups.

8. Biomaterial according to any one of the preceding claims, characterized in that the filling network consists of one or more resorbable or non-resorbable polymers.

9. Biomaterial according to claim 8, characterized in that the polymers which can be used as filling network are chosen from alginates, pectins, hyaluronic acid, carrageenans, agarose, agaropectins, amyloses, amylopectins, arabino-galactans, cellulose and its derivatives, chitosan, tragacanth, gum arabic, guar gum , xanthans, dextrans, collagen and gelatins.

10. Biomaterial according to claim 9, characterized in that the filling network is an alginate gel comprising from 30% to 75% of α-L-guluronic acid units.

11. Biomaterial according to any one of the preceding claims, characterized in that the filling network contains at least one biological and / or chemical active.

12. Biomaterial according to claim 11, characterized in that the biological and / or chemical active agent is chosen from anti-inflammatory agents, angiogenic agents, anti-mitotics, angiogenesis inhibitors, growth factors , vitamins, hormones, proteins, vaccines, peptides, antiseptics, antimicrobials such as antibiotics.

13. Biomaterial according to any one of the preceding claims, characterized in that it is in the form of film, block, sheet, rod, wire or particles such as microspheres.

14. Porous biomaterial characterized in that it consists of a porous microsphere consisting of acrylic copolymers modified or not by ionized or ionizable functional groups chosen from the groups

(Cι-C4) alkylamino and (C | -C ₄ ) alkylamino (Cι-C ₄ ) alkyl, the pores of said microsphere being filled with a porous alginate gel, the pores of which contain at least one biological active agent and / or chemical.

15. Process for the preparation of a biomaterial as defined in any one of the preceding claims, characterized in that it comprises the following steps: a) the impregnation of at least one porous hydrophilic or amphiphilic polymer (support network ) with an aqueous solution (A) of at least one filler polymer in the liquid state, b) impregnation of said hydrophilic or amphiphilic porous polymer with an aqueous solution (B) of at least one agent capable of passing said filling polymer from the liquid state to the gelled state, and optionally c) the impregnation said porous hydrophilic or amphiphilic polymer by a composition (C) containing at least one biological and / or chemical active agent, said impregnation being able to be carried out concomitantly in steps a) and b) by addition of composition (C) in one and / or the other of solutions (A) and (B) or separately after steps a) and b).

16. The method of claim 15, characterized in that the support network is, in a first step, impregnated by means of the solution (A), then in a second step, by the solution (B), the composition (C ) being added to solution (A) and / or (B).

17. The method of claim 15 or 16, characterized in that the concentration of filling polymer in the solution (A) preferably varies from 0.01 to 2% by weight relative to the total weight of the solution (A) .

18. Method according to any one of claims 15 to 17, characterized in that the filling polymer in the liquid state is an alginate and that the agent capable of passing said filling polymer from a liquid state to a gelled state is chosen from multivalent ions, preferably calcium ions.

19. Method according to any one of claims 15 to 18, characterized in that the aqueous solutions (a) and / or (b) and / or the composition (C) contain at least one surfactant.

20. Use of a biomaterial as defined in any one of claims 1 to 14 as an implant or device for the controlled release of at least one biological and / or chemical active.

21. Device for the controlled release of at least one biological and / or chemical active agent, characterized in that it comprises at least one biomaterial as defined in any one of claims 1 to 14.

22. Composition characterized in that it contains at least one biomaterial as defined in any one of claims 1 to 14.

23. Solution for injection for intra-tissue or intravascular implantation characterized in that it contains at least one biomaterial as defined in any one of claims 1 to 14.