Papers by Author: M. Calasans-Maia

Abstract: The objective of this study was to investigate the bone repair of carbonate apatite (cHA) in comparison to hydroxyapatite (HA, control group), on osseous repair of non-critical size defect in rat calvaria. Spheres (400<ø>500μm) of both materials were synthesized under 37°C (cHA) and 90°C (HA) and were not sintered. Fifteen rats Wistar were submitted to general anesthesia and two perforations (4mm each) were made, one in each parietal bone, for implantation of cHA (left side) and HA spheres (right side). After 1, 3 and 6 weeks, five animals of each group were killed and the two fragments with the biomaterial were collected from the calvaria. The bone blocks with biomaterial were demineralized and 5μm thick semi-serial sections were done for histological analysis. The experimental group of 6 weeks did not show the presence of spheres of both biomaterials and few spheres were observed after 1 and 3 weeks. Histological analysis showed the connective tissue repairing the surgical defect after 1 week and newly formed bone after 3 weeks of surgery. Thus, we concluded both materials are biocompatible, promote osteoconduction and in all studied periods the biomaterials showed to be resorbable.

Abstract: The objective of this study was to investigate the in vitro and in vivo biological responses to carbonate apatite (cHA) in comparison to hydroxyapatite (HA). Spheres (400<ø>500 μm) of both materials were synthesized under 5°C (cHA) and 90°C (HA) and not sintered. The in vitro cytocompatibility was determined by the XTT assay, according to ISO 10993-5:2009, after exposure of MC3T3-E1 cells to the materials extracts. Ethics Commission on Teaching and Research in Animals approved this project (CEPA/NAL 193/10) and, subsequently, the biomaterials were grafted in the subcutaneous tissues of mice (n=15). After 1 and 3 weeks, five animals of each group were killed for samples removal containing biomaterials and surrounding tissues for histological examination. Semi-serial (5-μm thick) sections were cut and stained with Hematoxylin and Eosin (HE) and the presence of inflammatory infiltrates and biomaterials resorption were evaluated. The experimental group of 3 weeks didn’t show the presence of spheres of both biomaterials and few spheres were observed after 1 week. Histological analysis showed the granulation tissue around the biomaterials with the presence of multinucleated giant cells. After 3 weeks it was observed the presence of fibrous tissue around biomaterials and few inflammatory cells. No signals of tissue necrosis were observed in both groups in all experimental studied periods. Nanostructured carbonate apatite spheres are cytocompatible, biocompatible and present initial biosorption on the subcutaneous comparable to stoichiometric HA, indicating its suitability for further studies on regenerative medicine.

Abstract: This study investigated the osteoinductive potential of granules of stoichiometric hydroxyapatite (HA) and 0.5% zinc containing hydroxyapatite (ZnHA) in intramuscular (IM) site of rabbit’s abdomen. The biomaterials were both used in granular form, with 75% porosity and particle diameter between 450 and 500μm, sintered at 1100°C. Both materials performed adequately on a multiparametric in vitro cytocompatibility assay, indicating their suitability for in vivo testing. After approval by the Ethics Commission on Teaching and Research in Animals, fifteen rabbits were submitted to general anesthesia, incision and tissue dilatation, and a small site was created for HA (right incision) and ZnHA (left incision) intramuscular implantation. The animals were killed after 2, 4 and 12 weeks for biomaterials and surrounding tissues removal. Histological analysis after 2 weeks revealed the presence of granulation tissue surrounding biomaterials with multinucleated giant cells and no newly formed bone for both materials. After 4 weeks there was fibrous tissue involving the material and few inflammatory cells. Following 12 weeks it was observed the presence of connective tissue surrounding the biomaterial, cellularized enough for the two experimental groups, but it was not observed the presence of bone matrix associated with the biomaterials. We conclude that both biomaterials are cytocompatible and did not present the property of osseoinduction after 12 weeks of implantation.

Abstract: The objective of this study was to investigate the bone repair of carbonate apatite (cHA) in comparison to hydroxyapatite (HA, control group) on osseous repair of rabbit’s tibia. Spheres (400-500 µm) of both materials were synthesized under 37°C (cHA) and 90°C (HA) and were not sinterized. Ethics Commission on Teaching and Research in Animals approved this project (CEPA/NAL 208/10). Six White New Zealand rabbits were submitted to general anesthesia and one perforation (2mm) was made in each tibia for implantation of cHA (left tibia) and HA spheres (right tibia). After 4 weeks all animals were killed and one fragment of each tibia with the biomaterial was collected with a total of 6 bone blocks for each group. Five bone blocks of each group were demineralized and 5-µm thick semi-serial sections were stain with Hematoxillin and Eosin and Trichromic of Masson for histological analysis and two fragments were collected and embedded in a methacrylate-based resin and cut into slices with ~30 µm and were analyzed by light microscopy (bright field and polarized microscopy). Both groups didn’t show the spheres after 4 weeks, new-formed bone was observed from the periphery toward to the center of the surgical defect, which was even filled with connective tissue. Both materials are biocompatible, promote osteoconduction and showed to be resorbable.