The use of autogenous venous graft with intraluminal injection of Schwann cells to enhance nerve regeneration of long segmental nerve defects was evaluated in a rabbit tibial nerve-repair model. Schwann cells were isolated from the excised rabbit tibial nerve by using the polylysine differential adhesion method. The cultured cells were identified by immunocytochemical labeling for S-100 protein. Tibial nerve defects in 4-cm segments were created in 24 animals, which were then divided into three groups. In Group 1, the tibial nerve defect was repaired with interposition vein graft alone; in Group 2, the nerve defect was repaired with a vein graft with intraluminal injection of Schwann-cell suspension; in Group 3, the nerve defect was repaired by autogenous nerve graft alone. At 2 months postoperatively, electrophysiologic evaluation showed that an evoked muscle action potential was recorded for the animals in Group 2, with vein grafting plus Schwann cells, and for those in Group 3, with autogenous nerve grafting, but not for those in Group 1, where vein grafting alone was used. The average motor nerve conduction velocity in the group with vein grafting and Schwann cells was 3.4 +/- 1.5 m/sec, which was slower than the nerve grafting group (7.8 +/- 1.8 m/sec). Histologic analysis confirmed there was formation of new nerve fascicles with myelination in the vein graft filled with Schwann cells. No nerve regrowth was found in the vein grafts without Schwann cells. These results suggested that isolated Schwann cells are able to survive in a vein graft, and that the vein graft with intraluminal seeded Schwann cells could be an alternative for repairing injured nerves with long gaps.

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Vascular grafts in animal models have been used extensively in the microsurgical laboratory, and the rat offers an excellent source of graft to meet these needs. In this study, we compiled a list of vessels that were previously identified in experimental literature for use as vascular grafts in the rat model. We then dissected and measured both arterial and venous grafts taken from these sites in 12 adult rats. The surgical procedure for approaching each vascular graft was recorded. The diameter and harvestable length, the start and end points, and the number of branches of the graft were tabulated. We believe that these data will provide valuable insight applicable to the use of the rat vascular graft in microsurgical research and training.

The effect of recipient-bed isolation with artificial barriers on skin-flap survival, compared to flap transfer without bed isolation, was evaluated in a modified rat epigastric skin-flap model. The pattern of blood flow in the raised flap with a proximal axial portion and distal random portion was confirmed by laser Doppler flowmetry. Forty rats were divided into four groups. Three of the groups had one of three different artificial barriers-silicone, polypropylene, or gelatin sponge. In each of these three groups, one of the artificial barriers was placed between the flap and its recipient bed after flap replacement. The flaps without bed isolation (Group 4) were used as controls. The survival area was measured 7 days postoperatively. Results demonstrated that necrosis in the groups with silicone and polypropylene barriers was significantly higher than in the controls. Histologically, neovascularization was shown in the flaps without artificial barriers. Foreign-body reactions were observed in the flaps with bed isolation and among these, severe inflammation and congestion were seen in the flaps with polypropylene isolation. In this study, the authors demonstrated that the random portion of a rat skin flap could survive partially through imbibition of plasma and the ingrowth of new vessels from the recipient bed. This neovascularization can be prevented by recipient-bed isolation with an artificial barrier. Bed isolation with a silicone sheet is suggested for use in the study of rat skin-flap survival.