Preliminary Study Of Treating Osteoporosis With Mesenchymal Stem Cells

Objective: The aim of this study is to investigate the feasibility of treating osteoporosis using adipose-derived stem cells(ASCs), and to detect the osteogenic potential of bone marrow cells in high density culture in order to evaluate whether these cells could be further used for bone engineering in the repair of bone defects in osteoporosis cases.Method: Osteoporosis rabbit models were established by bilateral oophorectomy and evaluated by X-ray. ASCs were harvested from all animals both before and 6 months after surgery. All harvested ASCs were tested for proliferation capacity as well as osteogenic differentiation potential. The expression of alkaline phosphatase and accumulation of calcium ions were measured after 4 weeks of osteogenic induction.Bone marrow cells from rats were cultured in high density dots and cells cultured in regular density were served as control. Osteogenic differentiation potential was evaluated by measuring alkaline phosphatase and calcium ions after 4 weeks of osteogenic induction. In addition, Q-PCR was performed to detect the mRNA level of osteocalcin, osteopontin and transcriptional factor Runx2 expression. Cells cultured in high and regular densities were mixed with calcium alginate gel respectively, and injected subcutaneously into nude mice. Osteogenic abilities were evaluated after 12 weeks of injection.Results:1. Proliferation of ASCs: Proliferation abilities of ASCs harvested before ovariectomy were greater than those harvested 6 months after ovariectomy in ovariectomy group as well as in sham group. However, no significant difference was found between ovariectomy and sham groups at 6 months post-surgery.2. Osteogenic ability of ASCs: Expression of alkaline phosphatase and accumulation of calcium ions were both significantly higher in ASCs harvested before ovariectomy compared with those harvested 6 months after ovariectomy(p<0.05). In addition, similar results were observed in sham group. However, no significant difference was found between ovariectomy and sham groups at 6 months post-surgery.3. Osteogenic potential of bone marrow cells in high density culture: Accumulation of calcium ions was significantly higher in regular density cultured cells than in high density cultured cells(p<0.05) after osteogenic induction, which was confirmed by Alizarin red staining.4. Osteogenic differentiation gene expression: mRNA expression of osteogenic differentiation genes, including osteocalcin, osteopontin and transcriptional factor Runx2, were significantly higher in regular density cultured cells than in high density cultured cells after osteogenic induction(p<0.05).5. The weight of tissue with ectopic osteogenic formed by bone marrow cells cultured in high density showed no statistical difference when compared with that formed by cells cultured in regular density. Calcification could be observed both in regular density group and high density group by histology, although bone tissue could not be found.Conclusion: Osteogenic abilities of ASCs harvested under osteoporotic conditions and aged animals were lower in comparison with those harvested in young healthy animals, indicating that ASCs from young healthy stage may be a priority selection in the treatment of osteoporosis.Osteogenic potential of bone marrow cells in high density culture is lower than those in regular density culture in vitro. However, the osteogenic potential of cells in vivo is still unclear and further investigation is needed.