Role of vascularity for successful bone formation and repair.

Tissue engineering has been touted as the solution to regenerate tissue in patients. Yet current strategies for orthopedic application are limited because of the inability to successfully manage critical sized defects without a working vascular system. Bone grafts are commonly used in critical sized defects to fill the gap in missing bone tissue. Proper vasculature is vital to the success of these grafts to promote bone growth. The aim of this review is to describe the contribution of tissues surrounding critical sized defects, focusing in particular on the progenitor cell influx and factors contributing to neovascularization. An overview of clinical techniques to visualize patient vascular supply and evaluation of clinical techniques to increase blood flow to the critical defect site illustrates the current efforts of surgical intervention to promote proper bone formation. The opportunity and need lies in the development of tissue engineered bone grafts that can use and enhance available vascular supplies.