Human skin processing affects clinical outcome in allograft recipients.

Skin allografts represent a milestone in burn patient treatment. However, skin procurement is still burdened by high rates of contamination, and validation procedures have not yet been standardized. In addition, it is not clear if tissue viability affects allograft skin outcomes. In 2120 skin samples from 610 donors, a retrospective analysis was performed to identify donor and procurement variables associated with bacterial contamination and tissue viability. Post-processing contamination was associated significantly with the donor type, cause of death, length of hospitalization, procurement site, surgeon, interval between procurement and banking, and decontamination method. Tissue viability appeared to be negatively associated with freezing. In two series of skin allograft recipients (155 and 195 patients), we evaluated the role of skin characteristics and procurement variables on clinical outcomes. We found that the length of hospitalization was associated significantly with donor age. Procalcitonin and PCR values in allograft recipients were correlated with the decontamination method. No significant associations were observed between tissue viability and clinical outcomes (length of hospitalization, cause of donor death, or inflammatory parameters) after allograft transplantation. In these large case series, we identified donor and procurement variables that may affect allograft skin recipients. The decontamination method appeared to be a critical step for skin allograft requiring better standardization.

AAV vector encoding human VEGF165-transduced pectineus muscular flaps increase the formation of new tissue through induction of angiogenesis in an in vivo chamber for tissue engineering: A technique to enhance tissue and vessels in microsurgically engineered tissue.

In regenerative medicine, new approaches are required for the creation of tissue substitutes, and the interplay between different research areas, such as tissue engineering, microsurgery and gene therapy, is mandatory. In this article, we report a modification of a published model of tissue engineering, based on an arterio-venous loop enveloped in a cross-linked collagen-glycosaminoglycan template, which acts as an isolated chamber for angiogenesis and new tissue formation. In order to foster tissue formation within the chamber, which entails on the development of new vessels, we wondered whether we might combine tissue engineering with a gene therapy approach. Based on the well-described tropism of adeno-associated viral vectors for post-mitotic tissues, a muscular flap was harvested from the pectineus muscle, inserted into the chamber and transduced by either AAV vector encoding human VEGF165 or AAV vector expressing the reporter gene ß-galactosidase, as a control. Histological analysis of the specimens showed that muscle transduction by AAV vector encoding human VEGF165 resulted in enhanced tissue formation, with a significant increase in the number of arterioles within the chamber in comparison with the previously published model. Pectineus muscular flap, transduced by adeno-associated viral vectors, acted as a source of the proangiogenic factor vascular endothelial growth factor, thus inducing a consistent enhancement of vessel growth into the newly formed tissue within the chamber. In conclusion, our present findings combine three different research fields such as microsurgery, tissue engineering and gene therapy, suggesting and showing the feasibility of a mixed approach for regenerative medicine.

A free vein graft cap influences neuroma formation after nerve transection.

INTRODUCTION: : Neuroma formation is a major problem in nerve surgery and consensus about its prevention has not been reached. It has been suggested that vein covering can reduce neuroma formation in transected nerves. In this article, the Authors propose an easy and novel method of covering by nerve stump capping with a free vein graft. METHODS: : Neuroma-like lesions were created on the rat thigh sectioning the femoral nerve above its division in 16 animals. The proximal nerve stump was invaginated into the lumen of a 1.5 cm long femoral free vein graft on the right side, and the vein was closed on itself by microsurgical sutures to form a cap for the nerve stump. On the left side acting as the control neuroma, the nerve was cut and left uncovered. Histological and immunohistochemical assessment was used to quantify the degree of neuroma formation. RESULTS: : Significant differences were found in both neuroma size and axon-glia organization between the treated and control sides indicating that free vein graft capping reduced neuroma formation in comparison to uncovered nerve stumps. CONCLUSIONS: : Our results confirm that vein-covering of a transected nerve stump can be effective in reducing neuroma formation. Moreover, unlike previous works that buried the nerve into an adjacent vein left in place, our experiments showed that also the use of a free vein graft cap can hinder neuroma formation. Although translation of rat experiments to the clinics should be dealt with caution, our data suggest a careful clinical use of the technique. (c) 2009 Wiley-Liss, Inc. Microsurgery, 2009.

An anterior-lateral thigh perforator flap on a recipient brachial-radial vein graft for complex wound reconstruction: a case report.

A case of challenging microsurgical reconstruction of a difficult defect in a radiated upper limb is reported. A difficult wound, with tendon and bone exposition, developed on the dorsum of the forearm in a 76-year-old patient; she had been radiated since almost 50 years and her left hand had also been revascularized twice with venous grafts between the humeral artery and the superficial palmar arch. After failure of a local flap, an anterior-lateral thigh perforator flap was successfully transferred with end-to-side anastomoses on the arterialized venous graft. Up to date follow-up shows a good outcome. The Authors discuss the case and review the indications for microsurgical reconstruction in difficult wounds after radiation and ischemic limb conditions.

The use of sentinel node biopsy and selective lymphadenectomy in squamous cell carcinoma of the upper limb. Usefulness of sentinel node biopsy to avoid useless lymphadenectomies in high-risk upper limb SCC.

BACKGROUND: Squamous cell carcinoma (SCC) is the second most common skin cancer in humans. Because the incidence of metastasis from SCC of the skin is rare, regional lymphadenectomy is generally not recommended for the patients with clinically node-negative disease. However, in patients with an intermediate and high risk of metastasis, evaluation of the lymph nodes to detect the absence of metastatic nodal disease is a difficult task. PATIENTS AND METHODS: The authors reviewed the pertinent demographic and surgical data in a consecutive series of six patients with squamous cell carcinoma who underwent sentinel lymph node staging. The tumour size was greater than 2 cm (T2) and the patients had clinically non-palpable regional lymph nodes (N0). All nodes were examined using haematoxylin-eosin staining. Sentinel Lymph Node Biopsy (SLNB) and Selective Lymphadenectomy (SL) using preoperative lymphoscintigraphy and intraoperative radiolymphoscintigraphy and vital dye injections was used to identify the sentinel lymph node avoiding complete axillary node dissection. RESULTS: No false-negative results were observed. At a median follow-up of 10 months (mean 15 months), neither local or regional recurrences in sentinel node-negative basins have been noted. CONCLUSIONS: Sentinel node biopsy is a minimally invasive staging procedure useful in identifying occult regional lymph node disease in selected patients with squamous cutaneous malignancies of the arm. Furthermore sentinel lymph node histology is possibly the most important negative predictor of early recurrence and survival in patients with American Joint Committee on Cancer stage I and II squamous cell carcinoma. Although sentinel node-negative patients are a prognostically favourable group, this small series of patients demonstrates that further studies to verify these findings and develop formal guidelines are indicated

Microsurgical arterovenous loops and biological templates: a novel in vivo chamber for tissue engineering.

BACKGROUND: Microsurgical tissue engineering is an emerging topic in regenerative medicine. Here we describe a new microsurgical model of bioengineering in rats based on the use of an arterovenous loop (AV) implanted into a commercially available crosslinked collagen/glycosaminoglycan template. METHODS: The microvascular loop was created between the femoral artery and vein and covered by the template folded onto itself. The chamber was isolated from the outside tissue by an outer silicon layer to impede tissue ingrowth. RESULTS: At 1-month postimplantation, the tissue chamber was found heavily vascularized, as assessed by laser Doppler perfusion analysis. Histological examination showed that the AV loop was integrated into the collagen matrix of the template and that the whole template was filled with a newly formed soft connective tissue. Most interestingly, the whole scaffold was found heavily vascularized, including the formation of a large number of alpha-SMA-positive arterioles. CONCLUSIONS: The developed microsurgical chamber provides a highly vascular, isolated tool for in vivo tissue engineering.

Ulnar nerve repair by end-to-side neurorrhaphy on the median nerve with interposition of a vein: an experimental study.

Our study used a rat animal model to verify that Schwann cell migration, collateral axonal sprouting, and regeneration were not hindered by interposition of a 10-mm vein segment between the distal stump of the transected ulnar nerve and the donor median nerve in end-to-side reconstruction. Reconstructed nerves were withdrawn at 7, 14, 30, and 60 days after surgery, then analyzed by confocal laser microscopy after immunolabeling with anti-neurofilament-200 kD (an axonal marker) and anti-S100 (a glial marker) antibodies. Results are reported at 7, 14, 30, and 60 days after surgery. Our observations indicate that chemotactic factors that stimulate end-to-side nerve regeneration can exert their action at this distance. These findings suggest a possible clinical application for this surgical technique in cases when the severed nerve stump is far from the potential donor nerve.