Intrinsic axial vascularization of an Osteoconductive bone matrix by means of an arteriovenous vascular bundle

Background: The purpose of this study was to generate an autonomously vascularized hard-tissue construct suitable for microsurgical transfer. The effector of vascularization was an arteriovenous bundle inserted into a specially designed channel in the matrix. The authors also evaluated corrosion cast and intravital magnetic resonance angiography as methods for monitoring and quantifying the angiogenic response. Methods: Thirty inbred male Lewis rats were divided into two groups. In both groups (n = 15), a disk of processed bovine cancellous bone matrix was placed into an isolation chamber. In group A, a ligated arteriovenous bundle was inserted into the biogenic matrix as a vascular carrier. In group B, there was no vascular carrier. At 2, 4, and 8 weeks after implantation, four constructs per group were evaluated by means of histology and histomorphometry and one by scanning electron microscopy of vascular corrosion casts. Micro-magnetic resonance angiography was used for intravital evaluation of the vascularized matrices. Results: Vascular density was higher in group A. The capillary network in group A displayed a higher degree of maturation, with organization into vessels of different orders. Both the sprouting and intussusceptive modes of angiogenesis could be documented. Micro-magnetic resonance angiography showed a patency rate of approximately 75 percent in the bundle. Conclusions: The authors zeroed in on the issue of vascularization. The results might provide a basis for further investigations on induction of bone formation in axially prevascularized matrices. Axially vascularized bone substitutes might solve issues of availability in mass and form and provide perfusion autonomy in sites of impaired circulation.