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Delayed repair of transected nerves: effect of brain-derived neurotrophic factor
1Division of Otolaryngology-Head and Neck Surgery, Stanford University Medical Center, Calif., USA.
Objective:
To determine if administration of brain-derived neurotrophic factor (BDNF) after peripheral nerve transection can improve the functional outcome 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, repaired with epineurial sutures. Animals were assigned to receive daily administration 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 assessed 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 group], 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 compared with the LR group, i.e., 2.43+/-0.23 microm (LR group), 2.80+/-0.44 microm (BDNF-early group), and 2.83+/-0.38 microm (BDNF-late group) (P = .05).
Conclusions:
The local administration of BDNF to nerves that underwent transection and then repair after a delay resulted in an increase in axonal diameters and maximal SFIs, a difference that did not reach statistical significance. The timing of BDNF administration after nerve transection did not affect neuronal regeneration.