Análise da osteogênese e incorporação óssea em enxertos ósseos humanos celularizados com células-tronco mesenquimais para aumento mandibular em ratos

Abstract

The use of allogeneic bone graft represents a viable alternative to autogenous bone for jaw reconstruction, as it reduces surgical time and trauma, with no pain and discomfort in a second donor site, has unlimited availability, low antigenic potential and ability to osteoconduction. However, it exhibits reduced osteoinductive capacity, slower incorporation into host bone and greater volumetric resorption. Some studies have tried to improve allografts with mesenchymal stem cells (MSCs) from the bone marrow, resulting in a greater volume of new bone formation in a shorter time. The aim of this study was to evaluate the potential for osteogenesis and incorporation of cellularized human bone grafts with MSCs, grafted in the rat mandible, and to compare with the use of non-cellularized human bone grafts. Twenty nude mice were allocated into two groups: the test group received cellularized human bone chips and the control group received the same bone microparticles, but without cells. Five animals from each group were euthanized at 4 weeks and the other five at 8 weeks. The results were analyzed by microcomputed tomography (micro-CT), histology, histomorphometry and immunohistochemistry. Micro-CT analysis showed significantly greater bone volume gain in the cellularized group than in the non-cellularized group at 4 weeks (34.97 ± 4.97mm3 vs 12.43 ± 2.53 mm3; p<0.001) and at 8 weeks (48.59 ± 3.99 mm3 vs 35.18 ± 4.98 mm3; p=0.002). The histomorphometric analysis showed that the percentage of newly formed bone was significantly higher in the cellularized group than in the non-cellularized group at 4 weeks (42.48 ± 5.38% vs 3.96 ± 2.83%; p<0.001) and at 8 weeks (48.40 ± 6.75% vs 23.01 ± 8.48%; p<0.001). The immunohistochemical results showed higher immunoexpression indices of anti-OCN, anti-OPN, anti-COL I and anti-TRAP in cellularized grafts than in acellular grafts. The parameters evaluated suggest that the cellular content present in the bone grafts for mandibular augmentation in rats promoted an early and efficient bone formation, with a higher rate of bone incorporation and remodeling.