Effects of photochemically immobilized polymer coatings on protein adsorption, cell adhesion, and the foreign body reaction to silicone rubber

Photochemical immobilization technology was utilized to covalently couple p olymers to silicone rubber either at multiple points along a polymer backbo ne or at the endpoint of an amphiphilic chain. The coating variants then we re tested in vitro and in vivo for improvement of desired responses compare d to uncoated silicone rubber. All coating variants suppressed the adsorpti on of fibrinogen and immunoglobulin G, and most also inhibited fibroblast g rowth by 90-99%. None of the coating variants inhibited monocyte or neutrop hil adhesion in vitro. However, the surfaces that supported the highest lev els of monocyte adhesion also elicited the lowest secretion of pro-inflamma tory cytokines. None of the materials elicited a strong inflammatory respon se or significantly (p< 0.05) reduced the thickness of the fibrous capsule when implanted subcutaneously in rats. Overall, the most passivating coatin g variant was an endpoint immobilized polypeptide that reduced protein adso rption, inhibited fibroblast growth by 90%, elicited low cytokine secretion from monocytes, and reduced fibrous encapsulation by 33%. In general, alth ough some coating variants modified the adsorption of proteins and the beha vior of leukocytes or fibroblasts in vitro, none abolished the development of a fibrous capsule in vivo. (C) 1999 John Wiley & Sons, Inc.