Effects of different HA/ZrO2 composites on adherence,proliferation and osteogenesis of cultured MSCs

AIM: To study the adherence, proliferation and osteogenesis effects of different composites on cultured mesenchymal stem cells (MSCs). METHODS: Zirconium oxide (ZrO₂) with monolayer hydroxyapatite (HA) composite and ZrO₂ with gradient HA composite were prepared using dry-laying method. The surface topography of the composites was observed. The rabbit MSCs were isolated and cultured on HA/ZrO₂ monolayer composite, HA/ZrO₂ gradient composite, pure HA or pure ZrO₂ slices. The adherence, proliferation and osteogenesis of the MSCs were assayed. The activity of alkaline phosphatase was detected. The mRNA expression of collagen I, osteocalcin and osteopontin was determined by RT-PCR. RESULTS: The discontinuous or continuous HA surface was observed in HA/ZrO₂ monolayer composite,while the surface of prepared HA/ZrO₂ gradient composite was fairly rough with porosity. The X-ray diffraction analysis shows that after megatemperature sintering, the ZrO₂ phase on the surface of the composite still remained, while the HA phase transformed to β-Ca₃(PO₄)₂(β-TCP), α-Ca₃(PO₄)₂(α-TCP) and CaZrO₃ phases. Cell culture showed that the HA/ZrO₂ gradient composite was in favour of cell adherence. The alkaline phosphatase activity in MSCs on pure HA slice was significantly increased compared compared with other groups.The mRNA expression of collagen I, osteocalcin and osteopontin in MSCs on HA/ZrO₂ composites and pure HA silice was higher than that in control group,especially the expression of collagen I. CONCLUSION: The HA/ZrO₂ garded composite promotes the proliferation of MSCs to a certain extent, and also promotes the osteogenesis differentiation of MSCs.