Effect of RGD-Immobilized Dual-Pore Poly(L-Lactic Acid) Scaffolds on Chondrocyte Proliferation and Extracellular Matrix Production

Interactions between cell and polymer surface have great implications in tissue engineering. In this study, chondrocyte proliferation and matrix production were examined using porous poly(l-lactide) (PLLA) scaffolds that have different surface characteristics. PLLA scaffolds were prepared using a gas-foaming method, and subjected to surface modifications through plasma treatment and subsequent in situ grafting of hydrophilic acrylic acid (AA). To immobilize peptide ligands, the AA-grafted PLLA scaffolds (PLLA-PAA) were further reacted with either Gly-Arg-Asp-Gly (GRDG) or Gly-Arg-Gly-Asp GRGD) to produce PLLA-PAA-GRDG or PLLA-PAA-GRGD scaffold, respectively. The average porosities of the scaffolds were more than 90%, and their pore sizes ranged from 200 similar to 300 to 10 similar to 50 mu m for large and small pores, respectively. The concentrations of each bound component were 2.14 X 10(-4) mmol/cm(2) for AA, 1.87 nmol/g for GRDG, and 1.68 nmol/g for GRGD. When chondrocytes were seeded onto the different PLLA scaffolds, cell adhesion and proliferation were highly affected as the substrate types vary. The RGD-immobilized scaffolds resulted in higher cellularity and better accumulation of total glycosaminoglycan than the others. Histological staining of Safranin O showed that the deposited extracellular matrix was more intense and widely distributed in the PLLA-PAA-GRGD scaffold. The present data suggest that immobilization of RGD peptide on the AA-grafted PLLA scaffold can be an effective tool for chondrocyte attachment and proliferation, and that it may also be helpful to facilitate cartilaginous tissue formation.