Adult Human Vein Grafts Retain Plasticity of Vessel Identity

Abstract

The spiral saphenous vein graft is an excellent choice for venous reconstruction after periphery vein injury, but only few cases have been reported. We implanted a segment of a single saphenous vein into both the popliteal vein as a venous vein graft and into the popliteal artery as an arterial vein graft at the same time in a trauma patient; we then had an extraordinary opportunity to harvest and examine both patent venous and arterial vein grafts at 2 weeks after implantation. A spiral saphenous vein graft was made as previously described and implanted into the popliteal vein and artery as interposition grafts; because of the patient's serious injuries, an amputation was performed at day 18 after vascular reconstruction. The grafts were harvested, fixed, and examined using histology and immunohistochemistry. Both grafts were patent, and there was a larger neointimal area in the venous graft compared to the arterial graft. There were CD31- and vWF-positive cells on both neointimal endothelia, with subendothelial deposition of α-actin-, CD3-, CD45-, and CD68-positive cells. There were fewer cells in the venous graft neointima compared to the arterial graft neointima; however, there were more inflammatory cells in the neointima of the venous graft. Some of the neointimal cells were PCNA-positive, whereas very few cells were cleaved caspase-3 positive. The venous graft neointimal endothelial cells were Eph-B4 and COUP-TFII positive, while the arterial graft neointimal endothelial cells were dll-4 and Ephrin-B2 positive. The spiral saphenous vein graft remains a reasonable choice for vessel reconstruction, especially in the presence of diameter mismatch. Both the venous and arterial grafts showed similar re-endothelialization and cellular deposition; the venous graft had more neointimal hyperplasia and inflammation. At an early time, endothelial cells showed venous identity in the venous graft, whereas endothelial cells showed arterial identity in the arterial graft. Veins can be used as venous or arterial vein grafts but venous grafts have more neointimal hyperplasia and inflammation; vein grafts acquire different vessel identity depending on the environment into which they are implanted.