Many more patients would benefit from vascularized composite allotransplantation if less toxic and safer immunosuppressive protocols will become available. Tolerance induction protocols with donor cells co-transplantation are one of the promising pathways to reduce maintenance immunosupressive regimens. We investigated the role of donor bone marrow cells (BMC), mesenchymal stromal cells (MSC) and in vivo created chimeric cells (CC) used as supportive therapies in a fully MHC-mismatched rat face transplantation model. Twenty-four fully MHC-mismatched hemiface transplantations were performed between ACI (RT1 a ) donors and Lewis (RT1 l
Peripheral nerves that are interrupted by trauma or surgical resection require reapproximation of their ends. When primary repair cannot be performed without undue tension, nerve grafting is required. Nerve repair with autograft is limited when there is insufficient amount of autologous nerves available for large nerve defects. This encouraged the search for alternative means of reconstruction in extensive nerve injuries. The cadaveric nerve allograft provides an unlimited graft source without the morbidities associated with autograft reconstruction; but these grafts are rapidly rejected unless appropriate recipient immunosuppression is achieved. An optimal treatment method for nerve allograft transplantation must minimize or prevent rejection while permitting nerve regeneration at the same time. In this report, the literature of nerve allograft transplantation experimental studies, strategies to prevent nerve allograft rejection, and reported clinical experiences are reviewed.
This report introduces the "neural-island flap" concept, which represents a consistent and reliable skin flap design supplied only by the intrinsic vasculature of a cutaneous nerve. In this study, the lateral femoral cutaneous nerve was selected as the pedicle of the neural-island flap, and a standard skin flap, which is the territory of the accompanying vessels (i.e., iliac branches of the iliolumbar artery and vein), was elevated on the lower dorsal region of the rats. In a total of 92 Wistar rats, three experiments were performed. In part I (n = 24), the vascular anatomy of the lateral femoral cutaneous nerve was established by the methods of dissection, microangiography, nerve mapping, perfusion with colored latex and India ink, and histologic analysis. In part II (n = 46), the role of the cutaneous nerve in supporting an acutely elevated skin flap was explored by creating five flap groups as follows: group 1, conventional flap (artery, vein, and nerve intact); group 2, neural island flap (only the nerve intact); group 3, neurocutaneous flap (vein and nerve intact); group 4, denervated flap (artery and vein intact); and group 5, skin graft. In part III (n = 22), the role of a preliminary surgical delay procedure to augment the survival of the neural island flap was investigated. Results of the anatomic studies indicated a consistent perineural vasculature by the accompanying iliolumbar artery. Skin flaps survived totally in groups where the artery and vein were intact, whereas mean survival rates for the neural island flap and the neurocutaneous flap were 38.2 +/- 3.1 percent and 44.5 +/- 3.8 percent, respectively (p > 0.05). Results of part III of the experiment demonstrated a significantly higher survival for the delayed neural island flap (94.5 +/- 5.5 percent) compared with the acutely elevated neural island flap (p < 0.05). The perineural and intraneural vessels were found to be greatly dilated after a delay procedure, demonstrated by direct observation, microangiography, histologic analysis, dye injection study, and scanning electron microscopy. On the basis of this promising series of experiments, a clinical technique was developed using the sural neural-island flap. The flap was used to reconstruct lower extremity defects in four cases. A delay procedure was accomplished in the first stage by elevating a fasciocutaneous flap from the midcalf region based on a posterior skin bridge and the sural nerve. After a 2-week delay period, a sural neural-island flap was created based on the nerve and transposed to the defect. Flap survival was complete in all cases, with a satisfactory result. The authors conclude that this report proves for the first time that a robust and reliable skin flap can be created pedicled only by the intrinsic vasculature of a cutaneous nerve, after a proper surgical delay. The so-created neural-island flap design offers two novel advantages: (1) a very narrow pedicle and (2) a pedicle without any restriction to a specific pivot point, in addition to the previously described unique a...
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