Delayed repair of transected nerves - Effect of brain-derived neurotrophicfactor

Objective: To determine if administration of brain-derived neurotrophic fac tor (BDNF) after peripheral nerve transection can improve the functional ou tcome in situations where epineurial repair must be delayed. Design: Randomized, blinded, controlled trial. Subjects: Thirty-four Sprague-Dawley rats. Intervention: Sciatic nerves were transected and, after a 2-week delay, rep aired with epineurial sutures. Animals were assigned to receive daily admin istration of lactated Ringer solution (LR [control] group), BDNF delivered at the time of nerve transection through 2 weeks after nerve repair, for a total of 4 weeks (BDNF-early group); or BDNF delivered at the time of nerve repair through 2 weeks after repair (BDNF-late group). Outcome was assesse d using sciatic functional indices (SFIs) and histomorphometric analysis. Results: The SFI maximal recovery was superior in the BDNF groups, but this difference did not reach statistical significance (SFI, -90.1 +/- 9.6 [LR group], -85.7 +/- 7.6 [BDNF-early group], and -84.6 +/- 4.8 [BDNF-late grou p], where normal function is 0 and complete loss of function is -100; P = . 27). The mean axon diameter tended to be greater in the BDNF groups compare d with the LR group, ie, 2.43 +/- 0.23 mu m (LR group), 2.80 +/- 0.44 mu m (BDNF-early group), and 2.83 +/- 0.38 mu m (BDNF-late group) (P = .05). Conclusions: The local administration of BDNF to nerves that underwent tran section and then repair after a delay resulted in an increase in axonal dia meters and maximal SFIs, a difference that did not reach statistical signif icance. The timing of BDNF administration after nerve transection did not a ffect neuronal regeneration.