IN-VITRO CHARACTERIZATION OF TRANSFORMING GROWTH FACTOR-BETA-1-LOADEDCOMPOSITES OF BIODEGRADABLE POLYMER AND MESENCHYMAL CELLS

A porous, biadegradable polymer composite was fabricated from poly(L-l actic acid) (PLLA) using a solvent-casting particulate-leaching techni que, and loaded with recombinant human transforming growth factor beta -1 (TGF-beta 1). Tissue culture polystyrene (TCPS) and PLLA disks load ed with bovine serum albumin (BSA) served as controls. Polymer specime ns were seeded at high cell density with C3H10T1/2 cells, a mouse embr yonic cell line capable of differentiating into various connective tis sue cell types. The polymer matrices degraded slowly in physiological saline over four weeks, with a sustained yet sporadic release of activ e TGF-beta 1; a more controlled release of TGF-beta 1 was observed in serum-containing culture medium and with cell seeding. Compared to con trols, cells seeded on TGF-beta 1-loaded PLLA disks showed significant ly enhanced DNA and proteoglycan synthesis, while collagen biosynthesi s was greater in all PLLA cultures compared to those on TCPS. Scanning electron microscopy revealed extensive cell proliferation, with a cho ndrocyte-like phenotype, throughout the porous matrix, while histology showed intact cell bodies and minimal cellular necrosis. These result s suggest that the TGF-beta 1-loaded cell-polymer composite supports c ell proliferation/differentiation, and is a candidate template for con nective tissue engineering.