Vascularized nerve tube: an experimental alternative for vascularized nerve grafts over short gaps

Multilayered tubes fabricated from human amnion were placed subcutaneously and/or longitudinally in contact with an axial artery and vein in rats. Histologic evaluation at the third postoperative week showed that the tubes had incorporated with the surrounding fibrovascular tissue. New capillary formation within the tube wall was well demonstrated by microangiography. Vascularized amnion tubes were then used to bridge a 1-cm-long femoral nerve gap in an artificially-created, relatively avascular bed in rats. An avascular bed was created by wrapping the corresponding nerve segment with a thin silicone sheet. After 3 months, nerve regeneration was assessed using morphometric analysis. The vascularized amnion conduits showed comparable nerve regeneration to vascularized nerve grafts (p > 0.05), and superior nerve regeneration when compared to nonvascularized amnion conduits and nonvascularized nerve grafts as well (p < 0.05). This suggests that, in the rat model, a conduit can be neovascularized and used as a prefabricated tissue, to bridge short nerve gaps in a compromised bed.