The beneficial effect of genetically engineered Schwann cells with enhanced motility in peripheral nerve regeneration: review.

BACKGROUND: The importance of Schwann cells in promoting nerve regeneration across a conduit has been extensively reported in the literature, and Schwann cell motility has been acknowledged as a prerequisite for myelination of the peripheral nervous system during regeneration after injury. METHODS: Review of recent literature and retrospective analysis of our studies with genetically modified Schwann Cells with increased motility in order to identify the underlying mechanism of action and outline the future trends in peripheral nerve repair. FINDINGS: Schwann cell transduction with the pREV-retrovirus, for expression of Sialyl-Transferase-X, resulting in conferring Polysialyl-residues (PSA) on NCAM, increases their motility in-vitro and ensures nerve regeneration through silicone tubes after end-to-side neurorraphy in the rat sciatic nerve model, thus significantly promoting fiber maturation and functional outcome. An artificial nerve graft consisting of a type I collagen tube lined with the genetically modified Schwann cells with increased motility, used to bridge a defect in end-to-end fashion in the rat sciatic nerve model, was shown to promote nerve regeneration to a level equal to that of a nerve autograft. CONCLUSIONS: The use of genetically engineered Schwann cells with enhanced motility for grafting endoneural tubes promotes axonal regeneration, by virtue of the interaction of the transplanted cells with regenerating axonal growth cones as well as via the recruitment of endogenous Schwann cells. It is envisaged that mixed populations of Schwann cells, expressing PSA and one or more trophic factors, might further enhance the regenerating and remyelinating potential of the lesioned nerves.

Poland syndrome in a female patient reconstructed by endoscopically assisted technique.

A two-stage, endoscopically assisted technique was used to reconstruct the chest wall and breast deformity in a female patient with Poland syndrome. In the first stage the latissimus dorsi muscle was transferred anteriorly, and a tissue expander was placed under the transposed muscle to adjust the size of the breast accordingly. In the second stage the same incision in the midaxillary line was used to remove the expander and place a permanent implant endoscopically. The two-stage technically demanding endoscopically assisted reconstruction of Poland syndrome was rewarded by inconspicuous scars and a fine aesthetic result.

Surfactant administration in severe inhalation injury: case report.

Inhalation injury is one of the main causes of death in patients with severe burns. Administration of exogenous surfactant appears promising for the treatment of acute respiratory failure. We report our clinical experience with this approach. A 35 yr-old man was admitted to our burns unit after an industrial accident. He had sustained a 60% total body surface area full-thickness burn combined with severe inhalation injury. Fiberoptic bronchoscopy confirmed the diagnosis, demonstrating severe blisters and ulcers of the bronchial mucosa. Refractory hypoxaemia (PaO (2)/FiO (2)56 mm Hg, where PaO (2)is oxygen tension in arterial blood and FiO (2)is the fraction of inspired oxygen) was treated with optimal mechanical ventilatory support; additionally, an initial dose of natural bovine surfactant (Alveofact) of 50 mg/kg body weight was administered by intrabronchial instillation on day 3 postburn. A significant improvement in oxygenation was observed 12 h after administration (from 56 mm Hg initially to 194 mm Hg), followed by an improvement in dynamic compliance (from 26 ml/cm H (2)O initially to 41 ml/cm H (2)O) and inspiratory resistance (from 14 cm H (2)O/lps initially to 11 cm H (2)O/lps). The same dose of surfactant was repeated 48 h later to prevent potential deterioration, resulting in maintenance of gas exchange and lung mechanics at the above levels. No complication associated with the surfactant administration was observed. However, the patient died on day 9 post-burn owing to extrapulmonary causes. Our results demonstrate a significant improvement in gas exchange and lung mechanics in a burn patient with severe inhalation injury after repeated administration of exogenous surfactant. Further study is needed in order to elucidate the clinical impact of surfactant administration and the complications associated with its use in cases of inhalation injury.

Microsurgical repair after crush-avulsion injury of the femoral vein in rats: prevention of microvascular thrombosis with recombinant human tissue-type plasminogen activator (rt-PA).

Vein thrombosis is often encountered in microsurgery, especially in the case of crush-avulsion injuries. The aim of this study was to investigate the effect of systemic administration of recombinant tissue-type plasminogen activator (rt-PA) on the patency of the femoral vein of the rat, which had previously sustained a crush-avulsion injury. The study consisted of 3 groups of male Wistar rats, 20 animals each. A standardized crush-avulsion injury model was used. After microvascular repair of the femoral vein, the animals received either normal saline (group A), heparin 100 U/kg body weight (group B), or rt-PA 3.5 mg/kg body weight (group C) systemically. Patency tests were performed at 20 minutes, 48 hours, and 1 week after blood flow reestablishment. According to our results, the patency rate of the rt-PA group was significantly higher than in both the control and heparin groups.

Prefabrication of an axial bio-synthetic flap for circumferential tracheal defect reconstruction.

The aim of this study was to prefabricate an axial bio-synthetic flap for reconstruction of circumferential tracheal defects in a rabbit model. Two series of experiments were performed. In the first set of experiments axial island bio-synthetic flaps were prefabricated. These consisted of an inner island de-epithelialised fasciocutaneous flap from a rabbit's ear and an outer polytetrafluoroethylene vascular graft. The flaps were buried at the base of the rabbit's ear for periods of 1, 2 and 3 weeks (groups A, B and C, respectively), 10 flaps per group. Only one flap in group C failed to survive. Clinical and histological assessment, at the completion of each time period, showed that only the viable flaps of group C developed all the characteristics needed for a tracheal substitute. In the second set of experiments the prefabricated bio-synthetic flaps were transferred to the rabbit's neck by means of microvascular anastomoses. Ten such free flaps were buried at the rabbit's neck for 3 weeks (group D). Eight of the flaps remained viable and all the viable flaps had characteristics similar to those of group C. These results demonstrate the feasibility of creating a prefabricated axial bio-synthetic flap (island or free), over a 3-week period, possessing the characteristics needed for a tracheal substitute in a rabbit model.