Dolph Houben

129 Transplant chimerism in bone VCA 6 calcified tissue [35, 36] , they are unlikely to be the source of bone remodeling and healing, at least in the laboratory rat model. Analyses of our current large animal bone allotransplantation model demonstrated similar outcomes with respect to areas of new bone formation. Although Group 1 cross-sections contained a lower percentage of extracted male DNA, the RNA extracted from these same pulverized whole bone sections demonstrated a trend towards more metabolic activity. This might be a possible effect of the autogenous angiogenesis. Analyses of RNA confirms the survival of some allogeneic cells in 6 out of 11 samples, although of unknown cell type (Fig. 8). Conclusion Vascularized composite allotransplantation of bone holds promise for future reconstruction of large segmental bone defects if the need for life-long immune modulation can be obviated. We have demonstrated a unique method to maintain viability, by switching the endosteal circulation of bone allotransplants from its original allogeneic nutrient blood supply to one of autogenous origin. In this report, we studied cell lineage within sex-mismatched bone VCAs by laser capture microdissection and RT-qPCR in a large animal model Analyses of areas of new bone formation showed significant levels of microchimerism, demonstrating new bone formation to result from the migration of autogenous cells. Some allogeneic male donor cells survived, demonstrated by RNA analyses. No systemic chimerism was found in the liver and spleen.