Osteoclast Features of Cells that Resorb Demineralized and Mineral-Containing Bone Implants in Rats

The comparative temporal tissue response to demineralized bone matrix powder (DBP) and devitalized mineral containing bone powder (MCP) implanted subcutaneously in rats was studied. The tissue response to implanted DBP followed the well described endochondral osteogenic pathway and included the appearance of osteoblasts and osteoclasts. On the other hand, implanted MCP resulted in the appearance of a large population of giant cells that resorbed the implants. At later times (3-4 weeks), most of the cells in the MCP implants appeared as typical foreign body giant cells with extensive membrane foldings, usually away from bone surface. Some cells did, however, have the histological appearance of osteoclasts, although this could not be completely confirmed by transmission electron microscopy. Scanning electron microscopy of anorganic preparations of the MCP following implantation showed resorption pits covering most of the surface, providing additional evidence that the resorption of bone by osteoclasts and giant cells may involve similar mechanisms. The observations suggest that both osteoclasts and giant cells may be involved with the resorption of ectopic MCP

Models of Hepatocellular Carcinoma and Biomarker Strategy

cancer

Antiresorptive and Anabolic Bone Therapy Does not Improve Weight Bearing Capacity and Bone Strength in OA Rats

Objective: This manuscript reports the outcomes of medial meniscectomy (MM) surgery on cartilage and cortical bone strength and the reaction of cartilage and bone to intensive treatment with antiresorptive (zoledronate) and anabolic bone (PTH) therapies.Methods: Medial meniscectomy was used to induce OA in male Lewis rats. Therapy with zoledronate and human PTH was initiated immediately after surgery. A dynamic weight-bearing system was deployed to evaluate the weight-bearing capacity. At the end of the 10-week study cartilage pathology was evaluated by contrast μCT imaging and histology. Cortical bone geometry at femoral mid-diaphysis was evaluated by μCT and strength was tested using 3-point bending method.Results: MM surgery caused negative consequences including cartilage deterioration, osteophyte formation, a decrease in weight-bearing capacity and decreased cortical bone strength.Conclusions: Treatment with zoledronate and PTH cannot prevent or correct the deterioration of the hyaline cartilage, osteophyte formation and the mechanical incapacity of the osteoarthritic knee. The partial and prolonged disuse of the osteoarthritic leg caused by the surgery has a deteriorating effect on cortical strength that was not corrected with anabolic or antiresorptive treatment. Our data suggest that early restoration of the mechanical function of the injured knee is a mandatory first step in preventing cartilage deterioration and supporting the recovery of joint structures and that a multitherapeutic approach is warranted to treat various aspects of post-traumatic osteoarthritis.</p