To investigate the effects of initial cell-seeding density and the compositions of biodegradable polymer scaffolds on the osteogenic differentiation of human mesenchymal stem cells.

Human mesenchymal stem cells (hBMSCs) were cultured three-dimensionally onto biodegradable polymers with three different compositions (65/35 PLGA, 85/15 PLGA, PLLA), and osteogenic differentiation was studied by; histology, immuno-histochemistry, and transmision/scanning electron microscopy.

In terms of the amount of extracellular matrix (ECM) produced, the 65/35 PLGA (23% of the whole volume) was found to produce more ECM than 85/15 PLGA (21%) and PLLA (13%). Osteoblastic differentiation of hBMSCs was induced in all scaffolds examined and the deposition of ECM with calcifications started after 2 weeks of culture. The amount of calcium deposited on the 65/35 PLGA dramatically increased at 4 weeks. On comparing low cell-seeding density with the high cell-seeding density on 65/35 PLGA, calcium deposits reached similar levels at 6 weeks.

Three-dimensional culture of hBMSCs on biodegrable polymer scaffolds induced bone formation, which was dependent on the compositions of the scaffolds and the initial cell-seeding density.