Quantitative assessment of angiogenesis and osteogenesis after transplantation of bone - Comparison of isograft and allograft bone in mice

We performed a vital microscopic study in mice bearing dorsal skinfold cham bers to characterize microvascular perfusion and leukocyte/endothelium inte raction and their effects on elongation and mineralization of neonatal isog raft and allograft bone. Isograft (C57/BL to C57/BL) and allograft bone (C5 7/BL to BALB/C) revascularized simultaneously. However, vascular perfusion and density were lower in allograft bone than in isograft bone. Leukocyte/e ndothelium interaction was the same in isograft and allograft bones. Revasc ularization was not detected in allograft bone transplanted to presensitize d recipients. Moreover, in preexisting Vessels at the trans-plantation site , leukocyte/endothelium interaction was altered in allograft bone of presen sitized recipients, despite a normal systemic leukocyte count. Femoral grow th resulting from thickening of both epiphyses did not differ between exper imental groups, however, mineralization occurred in isograft hone only Isog raft bone was histologically intact, allograft bone hypovital and allograft bone in presensitized recipients necrotic 12 days after implantation. Our findings suggest that graft incorporation or rejection is mediated by the m icrovasculature and that presensitizing of recipients accelerates rejection of allograft bone.