Tissue engineering skin flaps: which vascular carrier, arteriovenous shunt loop or arteriovenous bundle, has more potential for angiogenesis and tissue generation?

This study was designed to clarify which vascular carrier, the arteriovenous shunt loop or the arteriovenous bundle, has more potential as a vascular carrier for an artificial skin flap in rats. An arteriovenous shunt loop was constructed between the femoral artery and vein using an interpositional artery (group I) or vein (group II) graft. For arteriovenous bundle groups, the femoral artery and vein were used and subdivided into two groups: distal ligation type (group III) and flow-through type (group IV). The vascular pedicle was wrapped with an artificial dermis and implanted beneath the inguinal skin for 4 weeks. For the control group, a folded sheet of artificial dermis without any vascular carrier was embedded. In experiment 1, the volumes of generated tissue within the artificial dermis were measured in the experimental and control groups (n = 5 in each group). In experiment 2, the origin of new blood vessels sprouting from the arteriovenous shunt loop and arteriovenous bundle were evaluated histologically. The volume of generated tissue in the shunt groups was significantly greater than that in the bundle groups (p < 0.01). However, the bundle groups also showed a great potential for producing new tissue. Serial histological studies showed that new capillaries were derived not only from the vasa vasorum of the femoral vessels but directly from the femoral vein in both the shunt and the bundle groups. This "sprouting" was extensively exhibited in the group III. Although the arteriovenous shunt loop showed a greater potential for producing new tissue and capillaries, the distal ligation type of bundle was thought to be an effective and practical vascular carrier for producing a tissue-engineered skin flap.