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ABSTRACT: The controlled delivery of nerve growth factor (NGF) to the peripheral nervous system has been shown to enhance nerve regeneration following injury, although the effect of release rate has not been previously studied with an affinity-based delivery system (DS). The goal of this research was to determine if the binding site affinity of the DS affected nerve regeneration in vivo using nerve guidance conduits (NGCs) in a 13-mm rat sciatic nerve defect. These DSs consisted of bi-domain peptides that varied in heparin-binding affinity, heparin and NGF, which binds to heparin with moderate affinity. Eight experimental groups were evaluated consisting of NGF with DS, control groups excluding one or more components of the DS within silicone conduits and nerve isografts. Nerves were harvested 6 weeks after treatment for analysis by histomorphometry. These DSs with NGF resulted in a higher frequency of nerve regeneration compared to control groups and were similar to the nerve isograft group in measures of nerve fiber density and percent neural tissue, but not in total nerve fiber count. In addition, these DSs with NGF contained a significantly greater percentage of larger diameter nerve fibers, suggesting more mature regenerating nerve content. While there were no differences in nerve regeneration due to varying peptide affinity with these DSs, their use with NGF enhanced peripheral nerve regeneration through a NGC across a critical nerve gap.
Journal of Biomaterials Science Polymer Edition 01/2010; 21(6):771-87. · 1.69 Impact Factor
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ABSTRACT: Extraneural scar reduction is an important goal in peripheral nerve microsurgery. The use of biosynthetic materials, such as Seprafilm , reduces postoperative adhesions in abdominopelvic gynecologic and orthopedic surgery. The study evaluates the safety of Seprafilm in proximity to nerve tissue in a noninjury (phase 1) and injury (phase 2) model. Phase 1 groups were: (1) sciatic nerve exposure and neurolysis (n = 15), (2) Seprafilm placement superficial to the nerve (n = 15), and (3) circumferentially wrapping Seprafilm around the nerve (n = 15). Outcome measures at 45 and 90 days included wound inspection, histomorphometry, and stereological analysis of vascularity. Phase II groups were: (1) sciatic nerve cut and repair alone (n = 15) or (2) nerve wrapped with Seprafilm (n = 15). Nerves were evaluated at 18, 32, and 42 days postoperatively, and animals underwent biweekly functional walking tracks. In phase I, no significant differences were detected between groups. In phase II, fewer perineural scar bands were seen with Seprafilm . Histomorphometric differences favoring Seprafilm at 18 days and favoring control at 42 days were noted ( P < 0.05), though no differences in functional outcomes were detected. Qualitatively less perineural scar tissue was seen when using Seprafilm . No functional or histological deleterious effects were noted from placing Seprafilm on intact nerves or cut and repaired nerves.
Journal of Reconstructive Microsurgery 04/2009; 25(6):345-54. · 1.43 Impact Factor
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ABSTRACT: The purpose of this study was to characterize the mechanism of unresponsiveness produced by the intraportal administration of ultraviolet-B (UV-B)-irradiated donor antigen. Pretreated Buffalo rats accepted Lewis nerve allografts, had decreased in vitro T-cell reactivity, and demonstrated nerve regeneration and recovery of limb function, while rejecting third-party nerve allografts. Regenerated nerve grafts were then retransplanted into a second naïve recipient. Rejection of the retransplanted allograft by naïve donor-strain, but not recipient-strain, animals suggests that the allografts were completely replaced by host tissue. Pretreated Buffalo rats were also given a second Lewis allograft after the first had regenerated. The second allograft was rejected and in vitro immune reactivity was comparable to naïve animals. Because the unresponsiveness state was extinguished with loss of exposure to donor antigen, these findings suggest that the intraportal administration of UV-B-irradiated donor antigen works by anergic or suppressive regulatory, rather than deletional, mechanisms.
Journal of Reconstructive Microsurgery 02/2004; 20(1):43-51. · 1.43 Impact Factor
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ABSTRACT: Purpose: The severe functional and sensory deficits seen following injury to peripheral nerves makes facilitation of nerve regeneration a primary goal of the reconstructive surgeon. This study examines whether daily administration of FK506 or Cyclosporin A expedites peripheral nerve regeneration following neurotmetic injury in a rat model Methods: Inbred Buffalo rats were randomized to three experimental groups. Group I rats served as untreated controls. Rats in groups II and III received daily subcutaneous CsA (5 mg/kg), and FK506 (1 mg/kg), respectively. Each animal underwent unilateral posterior tibial nerve transection with immediate epineurial reapproximation. Functional recovery of the injured limb was assessed by serial walking track analysis. Nerve regeneration was assessed histomorphometrically via light microscopy. Results: Return of hindlimb function in control animals occurred at 32 days post injury. CsA and FK506-treated transection animals recovered at 26 and 18 days post injury, respectively. Statistically significant greater fiber density and percent neural tissue were seen in FK506- treated animals compared to control animals four weeks post transection. Conclusions: This data suggest that the daily systemic administration of both CsA and FK506 accelerate the rate of functional regeneration, following neurotmetic injuries in tbc rat model. FK506's effect on nerve growth is significantly greater than that of CsA.
Restorative neurology and neuroscience 02/2000; 17(1):39-44. · 2.51 Impact Factor
