PMID- 25181499 OWN - NLM STAT- MEDLINE DCOM- 20150518 LR - 20211021 IS - 1932-6203 (Electronic) IS - 1932-6203 (Linking) VI - 9 IP - 9 DP - 2014 TI - Electrical stimulation promotes regeneration of defective peripheral nerves after delayed repair intervals lasting under one month. PG - e105045 LID - 10.1371/journal.pone.0105045 [doi] LID - e105045 AB - BACKGROUND: Electrical stimulation (ES) has been proven to be an effective means of enhancing the speed and accuracy of nerve regeneration. However, these results were recorded when the procedure was performed almost immediately after nerve injury. In clinical settings, most patients cannot be treated immediately. Some patients with serious trauma or contaminated wounds need to wait for nerve repair surgery. Delays in nerve repair have been shown to be associated with poorer results than immediate surgery. It is not clear whether electrical stimulation still has any effect on nerve regeneration after enough time has elapsed. METHODS: A delayed nerve repair model in which the rats received delayed nerve repair after 1 day, 1 week, 1 month, and 2 months was designed. At each point in time, the nerve stumps of half the rats were bridged with an absorbable conduit and the rats were given 1 h of weak electrical stimulation. The other half was not treated. In order to analyze the morphological and molecular differences among these groups, 6 ES rats and 6 sham ES rats per point in time were killed 5 days after surgery. The other rats in each group were allowed to recover for 6 weeks before the final functional test and tissue observation. RESULTS: The amounts of myelinated fibers in the distal nerve stumps decreased as the delay in repair increased for both ES rats and sham ES rats. In the 1-day-delay and 1-week-delay groups, there were more fibers in ES rats than in sham ES rats. And the compound muscle action potential (CMAP) and motor nerve conduction velocity (MNCV) results were better for ES rats in these two groups. In order to analyze the mechanisms underlying these differences, Masson staining was performed on the distal nerves and quantitative PCR on the spinal cords. Results showed that, after delays in repair of 1 month and 2 months, there was more collagen tissue hyperplasia in the distal nerve in all rats. The brain-derived neurotrophic factor (BDNF) and trkB expression levels in the spinal cords of ES rats were higher than in sham ES rats. However, these differences decreased as the delay in repair increased. CONCLUSIONS: Electrical stimulation does not continue to promote nerve regeneration after long delays in nerve repair. The effective interval for nerve regeneration after delayed repair was found to be less than 1 month. The mechanism seemed to be related to the expression of nerve growth factors and regeneration environment in the distal nerves. FAU - Xu, Chungui AU - Xu C AD - Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, P.R. China. FAU - Kou, Yuhui AU - Kou Y AD - Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, P.R. China. FAU - Zhang, Peixun AU - Zhang P AD - Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, P.R. China. FAU - Han, Na AU - Han N AD - Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, P.R. China. FAU - Yin, Xiaofeng AU - Yin X AD - Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, P.R. China. FAU - Deng, Jiuxu AU - Deng J AD - Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, P.R. China. FAU - Chen, Bo AU - Chen B AD - Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, P.R. China. FAU - Jiang, Baoguo AU - Jiang B AD - Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, P.R. China. LA - eng PT - Journal Article DEP - 20140902 PL - United States TA - PLoS One JT - PloS one JID - 101285081 RN - 0 (Brain-Derived Neurotrophic Factor) RN - EC 2.7.10.1 (Receptor, trkB) SB - IM MH - Action Potentials MH - Animals MH - Axons/pathology MH - Brain-Derived Neurotrophic Factor/metabolism MH - Disease Models, Animal MH - Electric Stimulation MH - Female MH - Motor Neurons/pathology MH - Muscles/physiopathology MH - Myelin Sheath/pathology MH - *Nerve Regeneration MH - Neural Conduction MH - Peripheral Nerves/pathology/*physiopathology MH - Rats, Sprague-Dawley MH - Reaction Time MH - Receptor, trkB/metabolism MH - Spinal Cord/pathology/physiopathology MH - Staining and Labeling MH - Time Factors MH - *Wound Healing PMC - PMC4152131 COIS- Competing Interests: The authors have declared that no competing interests exist. EDAT- 2014/09/03 06:00 MHDA- 2015/05/20 06:00 PMCR- 2014/09/02 CRDT- 2014/09/03 06:00 PHST- 2013/10/22 00:00 [received] PHST- 2014/07/20 00:00 [accepted] PHST- 2014/09/03 06:00 [entrez] PHST- 2014/09/03 06:00 [pubmed] PHST- 2015/05/20 06:00 [medline] PHST- 2014/09/02 00:00 [pmc-release] AID - PONE-D-13-43243 [pii] AID - 10.1371/journal.pone.0105045 [doi] PST - epublish SO - PLoS One. 2014 Sep 2;9(9):e105045. doi: 10.1371/journal.pone.0105045. eCollection 2014.