Comb copolymers for regulating cell-surface interactions

• US 20010027237A1
• Filed: 03/26/2001
• Published: 10/04/2001
• Est. Priority Date: 04/13/1998
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Irvine, Darrell J., Johnson, Terry D., Banerjee, Pallab, Mayes, Anne M., Griffith, Linda G.
• Granted Patent: US 6,399,700 B2
• Time in Patent Office: Days
• US Class Current: 525/326.1
• CPC Class Codes: A61K 31/74 Synthetic polymeric materials
• CPC Class Codes: A61K 47/50 the non-active ingredient being chemically bound to the active ingredient, e.g. polymer-drug conjugates
• CPC Class Codes: A61K 47/56 the modifying agent being an organic macromolecular compound, e.g. an oligomeric, polymeric or dendrimeric molecule
• CPC Class Codes: A61K 47/641 Branched, dendritic or hypercomb peptides
• CPC Class Codes: C08G 81/00 Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers involving only carbon-to-carbon unsaturated bond reactions C08F299/00 ; polyester-amides C08G69/44; polyester-imides C08G73/16; polyamides-imides C08G73/14; block- or graft polymers containing polysiloxane sequences C08G77/42
• CPC Class Codes: C08G 81/024 Block or graft polymers containing sequences of polymers of C08C or C08F and of polymers of C08G

Abstract

Synthetic comb copolymers which elicit controlled cellular response, methods of applying these polymers to various surfaces, and methods of using the polymers for modifying biomaterial surfaces, in tissue engineering applications and as drug delivery devices are provided. The comb copolymers are comprised of hydrophobic polymer backbones and hydrophilic, non-cell binding side chains which can be end-capped with cell-signaling ligands that guide cellular response. By mixing non-cell binding combs with ligand-bearing combs, the surface concentration and spatial distribution of one or more types of ligands, including adhesion peptides and growth factors, can be tuned on a surface to achieve desired cellular response. In one embodiment, the combs are used as stabilizing agents for dispersion polymerization of latexes. The comb-stabilized latexes can be applied to substrates by standard coating operations to create a bioregulating surface, or used as drug delivery agents. In another embodiment, the combs can be blended in small quantities to a hydrophobic matrix polymer and processed to affect the surface segregation of the comb. The comb copolymers are formed in one embodiment by providing a biodegradable polyester backbone that includes reactive groups, and reacting the reactive groups in the backbone with reactive chain ends on a low molecular weight hydrophilic polymer. In another embodiment, non-biodegradable comb copolymers are formed by free radical synthesis of a hydrophobic monomer and a hydrophilic macromonomer. In all of the above embodiments, a portion of the hydrophilic polymer side chains can be covalently coupled to cell-signaling ligands such as adhesion peptides or growth factors to control cellular response.

Claims

1. A cell-regulating, comb-type copolymer comprising:

a) a hydrophobic polymer backbone;

b) non-cell binding hydrophilic polymeric side chains grafted to the polymer backbone, wherein the side chains have a molecular weight between 200 and 2000 Daltons;

wherein between zero and 100% of the non-cell binding, hydrophilic side chains are end-capped with cell-binding or cell-signaling ligands to form short cell-binding copolymer side chains and

wherein the side chains comprise less than 60% of the total copolymer weight.

2. The comb copolymer of

claim 1

having a total molecular weight of greater than 10,000 Daltons.

3. The comb copolymer of

claim 1

, wherein the backbone is biodegradable.

4. The copolymer of

claim 1

, wherein the backbone is non-biodegradable.

5. The copolymer of

claim 1

wherein the side chains are less than 500 Daltons and constitute less than 60% of the total copolymer weight.

6. The copolymer of

claim 1

wherein the mole percentage of backbone segments attached to hydrophilic side chains is between 2 and 30%.

7. The copolymer of

claim 1

wherein the percent of hydrophilic side chains which include functional groups capable of being covalently or ionically attached to a cell-binding or cell-signaling ligand is between 1 and 20%.

8. The copolymer of

claim 1

, wherein the non-cell binding side chains are selected from the group consisting of polyethylene glycol, polyethylene oxide, polyacrylic acid and dextran.

9. The copolymer of

claim 1

, wherein the ligands are selected from the group consisting of adhesion peptides, cell-signaling peptides and growth factors.

10. The copolymer of

claim 1

in a mixture further comprising non-cell-binding comb copolymers whose side chains are not end-capped with cell-binding or cell-signaling ligands.

11. The comb copolymer mixture of

claim 10

wherein less than 20% of the comb copolymers comprise side chains that are end-capped with cell-binding or cell-signaling ligands.

12. A tissue engineering matrix, cell culture matrix, biomedical device, or implant formed of or coated with the cell-regulating, comb-type copolymer comprising:

a) a hydrophobic polymer backbone;

b) non-cell binding hydrophilic polymeric side chains grafted to the polymer backbone, wherein the side chains have a molecular weight between 200 and 2000 Daltons;

wherein between zero and 100% of the non-cell binding, hydrophilic side chains are end-capped with cell-binding or cell-signaling ligands to form short cell-binding copolymer side chains and

wherein the side chains comprise less than 60% of the total copolymer weight,

wherein the comb copolymer is effective in regulating cellular adhesion or response to the surface.

13. The tissue engineering matrix, cell culture matrix, biomedical device or implant of

claim 12

seeded with cells selected from the group consisting of parenchymal cells, skin cells, muscle cells, cartilage cells, nerve cells and bone cells.

14. The tissue engineering matrix, cell culture matrix, biomedical device or implant of

claim 12

wherein the cell-regulating, comb-type copolymer comprises defined mixtures of non-cell binding and ligand-modified cell-regulating, comb-type copolymers.

15. The tissue engineering matrix, cell culture matrix, biomedical device or implan of

claim 14

, wherein the surface presents discrete nanodomains or clusters of a single ligand type against a background of non-cell binding hydrophilic side chains.

16. The tissue engineering matrix, cell culture matrix, biomedical device or implant of

claim 15

, wherein each nanodomain or cluster contains between 2 and 50 cell-signaling ligands in an area of 0.0001-0.01 microns square, with the overall spacing between the edges of such domains in the range 3-200 nm.

17. The tissue engineering matrix, cell culture matrix, biomedical device or implant of

claim 14

, wherein the surface presents discrete nanodomains or clusters of two or more ligand types against a background of non-cell binding hydrophilic side chains.

18. The tissue engineering matrix, cell culture matrix, biomedical device or implant of

claim 17

, wherein each nanodomain or cluster contains between 2 and 50 cell-signaling ligands in an area of 0.0001-0.01 microns square, with the overall spacing between the edges of such domains in the range 3-200 nm.

19. A method for making a tissue engineering matrix, cell culture matrix, implant or biomedical device with regulated cellular adhesion or response comprising coating or forming the matrix, implant or device with a comb copolymer comprising:

a) a hydrophobic polymer backbone;

b) non-cell binding hydrophilic polymeric side chains grafted to the polymer backbone, wherein the side chains have a molecular weight between 200 and 2000 Daltons;

wherein between zero and 100% of the non-cell binding, hydrophilic side chains are end-capped with cell-binding or cell-signaling ligands to form short cell-binding copolymer side chains and

wherein the side chains comprise less than 60% of the total copolymer weight.

20. The method of making a tissue engineering matrix, cell culture matrix, biomedical device or implant of

claim 19

in which non-cell binding side chains of the comb copolymers at the surface are end-capped with ligands after the coating, matrix, device or implant is formed.

21. A method for engineering tissue comprising growing cells on a tissue-engineering matrix formed of or coated with the cell-regulating, comb-type copolymer comprising:

a) a hydrophobic polymer backbone;

b) non-cell binding hydrophilic polymeric side chains grafted to the polymer backbone, wherein the side chains have a molecular weight between 200 and 2000 Daltons;

wherein between zero and 100% of the non-cell binding, hydrophilic side chains are end-capped with cell-binding or cell-signaling ligands to form short cell-binding copolymer side chains and

wherein the side chains comprise less than 60% of the total copolymer weight,

wherein the comb copolymer is effective in regulating cellular adhesion or response to the surface.

22. A polymer latex comprising polymer particles dispersed in aqueous-containing media stabilized by cell-regulating, comb-type copolymer comprising:

a) a hydrophobic polymer backbone;

b) non-cell binding hydrophilic polymeric side chains grafted to the polymer backbone, wherein the side chains have a molecular weight between 200 and 2000 Daltons;

wherein between zero and 100% of the non-cell binding, hydrophilic side chains are end-capped with cell-binding or cell-signaling ligands to form short cell-binding copolymer side chains and

wherein the side chains comprise less than 60% of the total copolymer weight.

23. The polymer latex of

claim 22

wherein the comb copolymers serve as a stabilizing agent during the latex synthesis.

24. The polymer latex of

claim 22

whereby the comb copolymer comprises less than 1% of the latex dry weight.

25. The polymer latex of

claim 22

further comprising non-cell-binding comb copolymers whose side chains are not end-capped with cell-binding or cell-signaling ligands.

26. The polymer latex of

claim 22

further comprising latex particles stabilized by non-cell binding comb copolymers to achieve a defined mixture of non-cell binding and ligand-modified cell-regulating latex particles.

27. The polymer latex of

claim 22

in which non-cell binding side chains of the comb copolymers at the surface of the particles are end-capped with ligands after the latex particles are synthesized.

28. Polymer coatings and films that regulate cell behavior prepared by casting a polymer latex comprising polymer particles dispersed in aqueous-containing media stabilized by cell-regulating, comb-type copolymers comprising:

a) a hydrophobic polymer backbone;

b) non-cell binding hydrophilic polymeric side chains grafted to the polymer backbone, wherein the side chains have a molecular weight between 200 and 2000 Daltons;

wherein between zero and 100% of the non-cell binding, hydrophilic side chains are end-capped with cell-binding or cell-signaling ligands to form short cell-binding copolymer side chains and

wherein the side chains comprise less than 60% of the total copolymer weight.

29. The polymer films and coatings of

claim 28

prepared by casting a mixed latex of microparticles stabilized with the non-cell binding comb copolymers to achieve a defined mixture of non-cell binding and ligand-modified cell-regulating latex particles.

30. The polymer films and coatings of

claim 28

comprising discrete domains of a single type of cell-signaling ligand against a background of non-cell binding hydrophilic side chains, where the domain size is on the order of the latex particles.

31. The polymer films and coatings of

claim 30

wherein the domain size is between 0.1 and 10 microns in diameter.

32. The polymer films and coatings of

claim 28

comprising discrete domains of multiple cell-signaling ligands against a background of non-cell binding hydrophilic side chains, wherein the domain size is on the order of the latex particles.

33. The polymer films and coatings of

claim 32

where the domain size is between 0.1 and 10 microns in diameter.

34. The polymer film or coating of

claim 28

in which non-cell binding side chains of the comb copolymers at the surface of the applied film or coating are end-capped with ligands after the coating or film is prepared.

35. A method of making polymer coatings and films that regulate cell behavior comprising casting a polymer latex comprising polymer particles dispersed in aqueous-containing media stabilized by cell-regulating, combtype copolymers comprising:

a) a hydrophobic polymer backbone;

b) non-cell binding hydrophilic polymeric side chains grafted to the polymer backbone, wherein the side chains have a molecular weight between 200 and 2000 Daltons;

wherein between zero and 100% of the non-cell binding, hydrophilic side chains are end-capped with cell-binding or cell-signaling ligands to form short cell-binding copolymer side chains and

wherein the side chains comprise less than 60% of the total copolymer weight.

36. The method of making polymer film or coatings of

claim 35

wherein non-cell binding side chains of the comb copolymers at the surface are end-capped with ligands after the coating or film is prepared.