Analysis of bone mineral density and bone turnover in the presence of polymethylmethacrylate particles

MC3T3-E1 osteoprogenitor cells systemically migrate to a bone defect and enhance bone healing

Although iliac crest autologous bone graft remains the gold standard for treatment of bone defects, delayed- and nonunions, and arthrodeses, several alternative strategies have been attempted, including the use of mesenchymal stem cells. Whether cells from the osteoblast lineage demonstrate systemic recruitment to an acute bone defect or fracture, and whether these cells directly participate in bone healing is controversial. This study tests two hypotheses: (1) that exogenous murine MC3T3-E1 osteoprogenitor cells with a high propensity for osteoblast differentiation are able to systemically migrate to a bone defect and (2) that the migrated MC3T3-E1 cells enhance bone healing. Two groups of nude mice were used; a bone defect was drilled in the left femoral shaft in both groups. MC3T3-E1 were used as reporter cells and injected in the left ventricle of the heart, to avoid sequestration in the lungs. Injection of saline served as a control. We used bioluminescence and microCT to assay cell recruitment and bone mineral density (BMD). Immunohistochemical staining was used to confirm the migration of reporter cells. MC3T3-E1 cells were found to systemically migrate to the bone defect. Further, BMD at the defect was significantly increased when cells were injected. Systemic cell therapy using osteoprogenitor cells may be a potential strategy to enhance bone healing.

Could insertion of the particles that induce osteolysis be a new treatment option in heterotopic ossification?

Heterotopic ossification (HO) is the formation of the bone outside the skeletal system, it is a common complication of surgery or trauma. The abnormal deposition or precipitation of calcium phosphate in tissues may be massive and clinically significant sometimes. Severe ossification often reduce joint function and induce pain. Unfortunately, to date, there is no satisfactory treatment available yet. Nowadays, periprosthetic osteolysis induced by wear debris is the most widely accepted cause of aseptic loosening after total joint replacement. A large number of researches have identified metal particles can stimulate bone resorption by targeting osteoclasts. So it is hypothesized that the insertion of metal particles in the region surrounding heterotopic bone could be a new treatment option in HO.