Stimulation of human mesenchymal stem cells and osteoblasts activities in vitro on silicon-releasable scaffolds

Cellular activities of human osteoblasts (HOBs) and mesenchymal stem cells (MSCs) on a silicon-releasable scaffold, siloxane-doped poly(lactic acid) and vaterite composite coated with hydroxycarbonate apatite (SPV-H), were estimated using a medium with or without organic factors, such as dexamethasone (Dex) and beta-glycerophosphate (beta-GP), for inducing mineralization or differentiation. As a control, a composite film containing no silicon (denoted by PV-H) was prepared using poly(lactic acid) and vaterite. HOBs cultured on SPV-H formed some agglomerates, bone nodules, after a 21-day culture in a medium without the organic factors, whereas no agglomerate was observed on PV-H. Laser Raman spectra implied that calcium phosphate precipitated in HOBs on the SPV-H. The silicon species in SPV-H stimulated HOBs to mineralization. The culture tests using MSCs show that the level of alkaline phosphatase (ALP) activity in the cells cultured on SPV-H increased during the 21-day culture in a medium without Dex and beta-GP. The level was unchanged in MSCs cultured on PV-H. In the case of supplementing Dex and beta-GP to the medium, the level of ALP activity in MSCs cultured on SPV-H was higher than that on PV-H at all time points during the 21-day culture. The silicon species in SPV-H were regarded to induce and enhance the osteogenic differentiation of MSCs.