Cells and Materials


A porous, biodegradable polymer composite was fabricated from poly(L-lactic acid) (PLLA) using a solvent- casting particulate-leaching technique, and loaded with recombinant human transforming growth factor ß-1 (TGF-ß1). Tissue culture polystyrene (TCPS) and PLLA disks loaded with bovine serum albumin (BSA) served as controls. Polymer specimens were seeded at high cell density with C3H10T1/2 cells, a mouse embryonic cell line capable of differentiating into various connective tissue cell types. The polymer matrices degraded slowly in physiological saline over four weeks, with a sustained yet sporadic release of active TGF-ß1; a more controlled release of TGF-ß1 was observed in serum-containing culture medium and with cell seeding. Compared to controls, cells seeded on TGF-ß1-Ioaded PLLA disks showed significantly enhanced DNA and proteoglycan synthesis, while collagen biosynthesis was greater in all PLLA cultures compared to those on TCPS. Scanning electron microscopy revealed extensive cell proliferation, with a chondrocyte-like phenotype, throughout the porous matrix, while histology showed intact cell bodies and minimal cellular necrosis. These results suggest that the TGF-ß1-loaded cell-polymer composite supports cell proliferation/differentiation, and is a candidate template for connective tissue engineering.