Adhesion and growth of rat aortic smooth muscle cells on lactide-based polymers

Biodegradable materials based on polymers of hydroxy acids are studied for application in artificial vascular substitutes. Polymers with functional surfaces are being developed, carrying specific recognition structures to affect selectively the adhesion and proliferation of endothelial cells (EC) and vascular smooth muscle cells (VSMC). This preliminary study focuses on evaluation of adhesion and growth of VSMC on surfaces of polylactide polymers and those modified by amphiphilic polylactide/poly(ethylene oxide) copolymers. Poly(L-lactic acid), PLLA, and poly(DL-lactic acid), PDLLA, and a block copolymer of lactide with a carboxylated poly(ethylene oxide) segment, PLLA-b-PEO-COOH, were synthesized by controlled polymerization of L and D,L-lactide, respectively, and using delta-hydroxy-Z-carboxymethyl-PEO as a macroinitiator for the copolymer. Films of polymers were deposited on glass coverslips by a spin-coating method. Uncoated glass coverslips and Falcon dishes were used as control substrates. VSMC were obtained from the thoracic aorta of young adult male Wistar rats by explantation method and seeded in Dulbecco-Modified Eagle MEM with 10% foetal bovine serum. The number of adhering cells, their shape, size of cell-material contact area and cell population doubling time were evaluated from day 1 to 7 after seeding. It was found that both PLLA and especially PDLLA relatively well supported adhesion and growth of VSMC. However, on carboxylated surfaces of the PLLA-b-PEO-COOH copolymer, a lower number of initially adhering cells (by 37% than on Falcon dishes, pdelta0.05), smaller cell spreading area (by 45% and 37% than on glass and Falcon dishes, respectively, pdelta0.01) and longer doubling time (by 49% and 31% than on glass and Falcon dishes, pdelta0.001). Thus, surfaces coated by a PLA/PEO-COOH copolymer can be used as minimum background surface to reveal the effect of other more specific adhesion structures.