Abstract: Objective: To evaluate the effect of SEMA3A released from matrigel on implant fixation in ovariectomized (OVX) rats. Methods: Sixty female rats were subjected to bilateral ovariectomy. Twelve weeks later, rats were randomly divided into three groups: 1) Control group: implants with distilled water; 2) Matrigel group: implants with matrigel coating; 3) Matrigel+SEMA3A group. Implants were inserted bilaterally in metaphysis of proximal tibiae in all animals. In vitro release of SEMA3A was tested using enzyme linked immunosorbent assay. Four and eight weeks after implantation, tibiae with implants were harvested for micro-CT, histology, and biomechanical push-out test. Results: In vitro release of SEMA3A was detectable during the first ten days, and a burst release was observed during the first three days. No significant difference was observed between Control and Matrigel group. Compared to matrigel alone, SEMA3A suspended in matrigel increased percent bone volume by 88.7% and 83.3%, trabecular thickness by 51.4% and 49.9%, trabecular number by 54.2% and 62.1% in micro-CT analysis at 4 and 8 weeks, respectively. SEMA3A suspended in matrigel also increased bone area density by 89.8% and 149.2%, bone-to-implant contact ratio by 148.9% and 24.8% in histological evaluation, and the maximal push-out force by 149.3% and 209.2%, stiffness by 171.2% and 210.6%, toughness 151.8% and 268.2%, at 4 and 8 weeks, respectively. Conclusion: Surface modification with SEMA3A suspended in matrigel improved implant osseointegration and fixation in the proximal tibiae of OVX rats.

Key words: Osteoporosis , Implant , Osseointegration, Semaphorin, 3A