Comparison of proliferation and osteoblast differentiation of marrow-derived mesenchymal stem cells on nano- and micro-hydroxyapatite contained composite scaffolds

Bones constructed by tissue engineering are being considered as valuable materials to be used for regeneration of large defects in natural bone. In an attempt to prepare a new bone construct, in this study, proliferation and bone differentiation of marrow-derived mesenchymal stem cells (MSCs) on our recently developed composite scaffolds of nano-, micro-hydroxyapatite/ poly(l-lactic acid) were compared with pure poly(l-lactic acid) scaffolds. For this purpose, some passaged-3 rat MSCs were three-dimensionally cultivated on the scaffold surfaces and their morphology was observed with scanning electron microscopy. Cell proliferations on different scaffolds were examined by MTT assays. Osteogenic cultures were established with the scaffolds loaded with MSCs for 21 days at the end of which culture mineralization; the cell alkaline phosphatase (ALP) Level and the relative expression of selected bone specific genes were quantified and compared to each other. Our results indicated that the cells having been adhered and assumed spherical morphology were able to proliferate in all studied scaffolds. The microenvironment provided by nano-scaffolds appeared much better medium than those of micro-scaffolds and pure PLLA (P < 0.05). The osteogenesis assays indicated to the superiority of nano-scaffolds in supporting MSCs undergoing bone differentiation, which was reflected in high cellular ALP levels, increased bone-related gene expression and enhanced culture mineralization. Collectively, the bone construct prepared with nano-hydroxyapatite/ poly (l-lactic acid) scaffold and proliferated MSCs would be suitable candidate for use in bone regenerative medicine.