Difference of adherence, proliferation and osteogenesis of mesenchymal stem cells cultured on different HA/ZrO2composites

ObjectiveTo study the adherence, proliferation and osteogenesis of mesenchymal stem cells (MSCs) cultured on different HA/ZrO2 composites.MethodsThe simplex and graded HA/ZrO2 composites were prepared using dry-laid method. The surface topography of the composites was observed by scanning electron microscope (SEM). The MSCs were isolated from rabbits and cultured on experimental groups (simplex HA/ ZrO2 composite, graded HA/ZrO2 composite, pure HA or pure ZrO2 coatings respectively) and control group (ordinary culture plate). Then, we observed the adherence, proliferation and osteogenesis of the MSCs, detected the cellular alkaline phosphatase (ALP) activities, extracted total RNA and detected the mRNA expression of collagen I, osteocalcin and osteopontin using the reverse transcription and poly-merase chain reaction (RT-PCR) method.ResultsThe SEM images confirmed that the surface of the simplex HA/ZrO2 composite was coverd by discontiguous HA layer with clear visualization of the partial ZrO2matrix,while the surface of the graded HA/ZrO2 composite was fairly rough with porosity. X-ray diffraction showed that after high temperature sintering,the ZrO2 phase still remained, while the HA phase was transformed to β-Ca3(PO4)2,α-Ca3(PO4)2 and CaZrO3 phases on the surface of both composites. Cell culture indicated that the HA/ ZrO2 composites supported cell attachment. Neither ALP expression nor mRNA expression of collagen I,osteocalcin or osteopontin from RT-PCR results showed significant deviation among four groups.ConclusionAmong these four composites, the graded HA/ZrO2 composite promotes the MSCs proliferation and the osteogenic differentiation to a certain extent.