OSTEOGENIC POTENTIAL OF NANOSTRUCTURED CARBONATED HYDROXIAPATITE MICROSPHERES ASSOCIATED WITH MESENCHYMAL STEM CELL IN VITRO AND IN VIVO

Background Bone tissue is capable of self-healing in the event of injuries. However, situations such as the patient‘s age or size of the damage can compromise natural healing, bringing to the fore the need for interventions to treat bone injuries. Tissue engineering presents treatment alternatives involving the use of cells and associated biomaterials. In this context, studies using biomaterials claim that carbonated hydroxyapatite (CHA) is more resorbable than hydroxyapatite (HA) and has biological similarity to bone hydroxyapatite. Methods Parameters of indirect contact (cytotoxicity, proliferation, and migration) of the extract obtained from spheres of carbonated hydroxyapatite associated with murine bone marrow stem cells (BMSCs) in vitro were evaluated. Then the osteogenic potential of CHA extract in murine BMSCs in vitro was assessed by quantification of calcium matrix, alkaline phosphatase levels and gene expression Col1A1 and Bglap. Non-critical size bone defects were performed in rat femur. After 14 days of healing, bone blocks were obtained for analysis from treated animals and compared to non-treated animals by histological and histomorphometric evaluation. Results The CHA extract showed osteoinductive properties in vitro without the need to add osteogenic inducing medium. The ability to induce osteogenic differentiation in undifferentiated cells was confirmed by increased activity of alkaline phosphatase, formation of mineralized nodules and increased expression of the Col1A1 and Bglap genes after 7 and 14 days of differentiation. All groups presented bone neoformation at the injury site 14 days after the operation. Histomorphometric analysis showed no statistical difference between groups in the parameters of bone formation, biomaterial and connective tissue. Conclusion The CHA spheres have in vitro osteoinductive properties and, when loaded with murine BMSCs, have the potential for bone repair and regeneration in vivo, presenting biocompatibility and osteoconductive, making it a promising alternative for bone tissue engineering applications.