Efficacy of sliced nerves of different thickness in a biodegradable nerve conduit to promote Schwann cell migration and axonal growth: An experimental study in the rat model.

BACKGROUND: Using the rat sciatic nerve model, sliced nerves of different thickness was combined to a biodegradable nerve conduit and the amount of nerve fragment necessary to promote nerve regeneration was investigated. MATERIALS AND METHODS: Harvested sciatic nerve (n = 6) was processed in sliced nerve of the different width; 2, 1, 0.5 mm, respectively. Western blot analysis was carried out to determine protein expression of Erk1/2. Subsequently, a total of 246 rats were used to create a 10 mm gap in the sciatic nerve. A polyglycolic acid-based nerve conduit was used to bridge the gap, with one sliced (width; 2, 1, 0.5 mm) or two (width; 1 mm × 2) incorporated within the conduit (n = 6 at each point in each group). At 2, 4, 8, and 20 weeks after surgery, samples were resected and subjected to immune-histological, transmission electron microscopic, and motor functional evaluation for nerve regeneration. RESULTS: Western blot analysis demonstrated Erk1/2 expressions were significantly increased in the groups of 2-mm and 1-mm width and attenuated in the 0.5-mm width group (p < .05). The immune-histological study showed the migration of Schwann cells and axon elongation were significantly extended in the groups of 2-mm, 1-mm, and 1 mm × 2 width at 4 weeks (p < .01), in which nerve conduction velocity was marked at 20 weeks (p < .01) after implantation. CONCLUSION: When nerve tissue was inserted in the biodegradable nerve conduit as a sliced nerve, the method of inserting two sheets with a slice width of 1 mm most strongly accelerated motor function.

Third Toe Pulp Reconstruction Using the Contralateral Second Toe Hemi-pulp Free Flap.

A hemi-pulp flap is widely known as a flap useful for aesthetic and functional reconstruction of the fingers, and rarely used for toe reconstruction. We performed third toe pulp reconstruction using a free hemi-pulp flap harvested from the contralateral second toe to repair the tissue defect following toe replantation. An 18-year-old woman was injured with complete left third toe amputation and open fracture of the proximal phalanx of the left second toe in a traffic accident. On the same day, third toe replantation was urgently performed. After surgery, the third toe was partially taken, and had a toe pulp tissue defect due to necrosis. It was reconstructed with a free hemi-pulp flap prepared from the contralateral second toe. The flap was completely taken. Three years after surgery, the reconstructed left third toe was aesthetically favorable. Perception of the flap region was restored up to S2 without pain and there was no complication such as numbness, callus, and ulceration. In the flap donor site (right second toe), the skin graft was unnoticeable without pigmentation. Toe pulp reconstruction requires a sensory flap as low-invasive as possible with excellent sensory restoration, texture, feel, and shear property. This method is considered as one of the low-invasive, aesthetic, and functional reconstruction methods.

Use of sliced or minced peripheral nerve segments for nerve regeneration through a biodegradable nerve conduit: A preliminary study in the rat.

BACKGROUND: Using the rat sciatic nerve model, the difference in outcome using a nerve segment either sliced open or minced with a blade incorporated into a nerve conduit were compared and the relative effects upon the rate and completeness of the nerve regeneration was determined. MATERIALS AND METHODS: A 10-mm gap was created in the rat sciatic nerve and bridged with a biodegradable nerve conduit. Segments of the resected nerve (2-mm lengths) were prepared by either slicing the nerve with one longitudinal cut or by scalpel mincing of the nerve tissue, with insertion of the prepared nerve segment into the center of the conduit. Flow cytometry and Western blotting of these preparations were performed to measure viable cells and to examine the expression of Erk1/2 for neural regeneration potential with both treatments. in vivo nerve regeneration was evaluated at 2, 4, 8, and 20 weeks, using immunohistochemistry, transmission electron microscopy, muscle wet weight, and nerve conduction velocity determination. RESULTS: The sliced nerve group showed significantly greater Schwann cell migration with the subsequent axonal elongation at 4 weeks after implantation, in comparison to the minced nerve group and controls (unaltered conduit grafts). By 20 weeks anterior tibial muscle weight and nerve conduction velocity were also greater in the sliced nerve group in comparison to the other groups (p < .05). CONCLUSION: These findings suggest that insertion of a sliced section of nerve into a biodegradable nerve conduit can shorten the time for and improve the quality of nerve regeneration.

Human Adipocyte Conditioned Medium Promotes In Vitro Fibroblast Conversion to Myofibroblasts.

Adipocytes and adipose tissue derived cells have been investigated for their potential to contribute to the wound healing process. However, the details of how these cells interact with other essential cell types, such as myofibroblasts/fibroblasts, remain unclear. Using a novel in-vitro 3D human adipocyte/pre-adipocyte spheroid model, we investigated whether adipocytes and their precursors (pre-adipocytes) secrete factors that affect human dermal fibroblast behavior. We found that both adipocyte and pre-adipocyte conditioned medium induced the migration of fibroblasts, but only adipocyte conditioned medium induced fibroblast differentiation into a highly contractile, collagen producing myofibroblast phenotype. Furthermore, adipocyte mediated myofibroblast induction occurred through a TGF-ß independent mechanism. Our findings contribute to a better understanding on the involvement of adipose tissue in wound healing, and may help to uncover and develop fat-related wound healing treatments.