Improvement of gait patterns in step-trained, complete spinal cord-transected rats treated with a peripheral nerve graft and acidic fibroblast growth factor

The effects of peripheral nerve grafts (PNG) and acidic fibroblast growth factor (αFGF) combined with step training on the locomotor performance of complete spinal cord-transected (ST, T8) adult rats were studied. Rats were assigned randomly to five groups (N = 10 per group): sham control (laminectomy only), ST only, ST-step-trained, repaired (ST with PNG and αFGF treatment), or repaired-step-trained. Step-trained rats were stepped bipedally on a treadmill 20 min/day, 5 days/week for 6 months. Bipolar intramuscular EMG electrodes were implanted in the soleus and tibialis anterior (TA) muscles of ST-step-trained (n = 3) and repaired-step-trained (n = 2) rats. Gait analysis was conducted at 3 and 6 months after surgery. Stepping analysis was completed on the best continuous 10-s period of stepping performed in a 2-min trial. Significantly better stepping (number of steps, stance duration, swing duration, maximum step length, and maximum step height) was observed in the repaired and repaired-step-trained than in the ST and ST-step-trained rats. Mean EMG amplitudes in both the soleus and TA were significantly higher and the patterns of activation of flexors and extensors more reciprocal in the repaired-step-trained than ST-step-trained rats. 5-HT fibers were present in the lumbar area of repaired but not ST rats. Thus, PNG plus αFGF treatment resulted in a clear improvement in locomotor performance with or without step training. Furthermore, the number of 5-HT fibers observed below the lesion was related directly to stepping performance. These observations indicate that the improved stepping performance in Repaired rats may be due to newly formed supraspinal control via regeneration.