RESUMEN
Hydroxyapatite (HA), a stable and biocompatible material for bone tissue therapy, may present a variable stoichiometry and accept a large number of cationic substitutions. Such substitutions may modify the chemical activity of HA surface, with possible impact on biocompatibility. In this work, we assessed the effects of calcium substitution with diverse divalent cations (Pb(2+), Sr(2+), Co(2+), Zn(2+), Fe(2+), Cu(2+), or Mg(2+)) on the biological behavior of HA. Physicochemical analyses revealed that apatite characteristics related to crystallinity and calcium dissolution/uptake rates are very sensitive to the nature of cationic substitution. Cytocompatibility was evaluated by mitochondrial activity, membrane integrity, cell density, proapoptotic potential, and adhesion tests. With the exception of Zn-HA, all the substituted HAs induced some level of apoptosis. The highest apoptosis levels were observed for Mg-HA and Co-HA. Cu-HA was the only material to impair simultaneously mitochondrial activity, membrane integrity, and cell density. The highest relative cell densities after exposure to the modified HAs were observed for Mg-HA and Zn-HA, while Co-HA significantly improved cell adhesion onto HA surface. These results show that changes on surface dissolution caused by cationic substitution, as well as the increase of metal species released to biological media, were the main responsible factors related to alterations on HA biocompatibility.
Asunto(s)
Cationes Bivalentes/metabolismo , Materiales Biocompatibles Revestidos/metabolismo , Durapatita/metabolismo , Animales , Apoptosis , Células 3T3 BALB , Cationes Bivalentes/química , Adhesión Celular , Células Cultivadas , Materiales Biocompatibles Revestidos/química , Durapatita/química , Fibroblastos/citología , Humanos , Ensayo de Materiales , Ratones , Osteoblastos/citologíaRESUMEN
O objetivo do presente trabalho foi estudar a citotoxicidade e a ativação de macrófagos em resposta à poliuretana derivada do óleo da mamona. A suspensão do material-tese na forma calcificada foi testada em cultura de macrófagos peritoniais obtidos a partir da labagem intraperitoneal de camundongos isogênicos C57/BL/6. Por meio de análise espectofotométricas, o material-teste revelou-se não-citotóxico ao interagir com mocrófagos peritoniais em cultura e foi constatado que, embora tenha induzido a liberação de NO em níveis relativamente baixos, não ativou macrófagos para a produção de H2O2. Portanto, concluímos que a poliuretana derivada do óleo da mamona apresentou um comportamento favorável à biocompatibilidade.