Allogeneic and autogenous transplantations of MSCs in treatment of the physeal bone bridge in rabbits

BACKGROUND The aim of this experimental study on New Zealand's white rabbits was to find differences in the results of treating the distal physeal femoral defect by the transplantation of autologous or allogeneic mesenchymal stem cells (MSCs). After the excision of a created bone bridge in the distal physis of the right femur, modified composite scaffold with MSCs was transplanted into the defect. In animal Group A (n = 11) autogenous MSCs were implanted; in animal Group B (n = 15) allogeneic MSCs were implanted. An iatrogenic physeal defect of the left femur of each animal not treated by MSCs transplantation served as control. The rabbits were euthanized four months after the transplantation. The treatment results were evaluated morphometrically (femoral length and valgus deformity measurement) and histologically (character and quality of the new cartilage). RESULTS Four months after the transplantation, the right femurs of the animals in Group A were on average longer by 0.50 +/- 0.04 cm (p = 0.018) than their left femurs, the right femurs of rabbits in Group B were on average longer by 0.43 +/- 0.01 cm (p = 0.028) than their left femurs.4 months after the therapeutic transplantation of MSCs valgus deformity of the distal part of the right femur of animals in Group A was significantly lower (by 4.45 +/- 1.86 degrees ) than that of their left femur (p = 0.028), in Group B as well (by 3.66 +/- 0.95 degrees than that of their left femur p = 0.001). However, no significant difference was found between rabbits with transplanted autogenous MSCs (Group A) and rabbits with transplanted allogeneic MSCs (Group B) either in the femur length (p = 0.495), or in its valgus deformity (p = 0.1597). After the MSCs transplantation the presence of a newly formed hyaline cartilage was demonstrated histologically in all the animals (both groups). The ability of transplanted MSCs to survive in the damaged physis was demonstrated in vivo by magnetic resonance, in vitro by Perls reaction and immunofluorescence. CONCLUSION The transplantation of both autogenous and allogeneic MSCs into a defect of the growth plate appears as an effective method of surgical treatment of physeal cartilage injury. However, the Findings point to the conclusion that there is no clear difference in the final effect of the transplantation procedure used.