To date, few treatment strategies applying cellular transplantation to the chronically injured spinal cord have yielded significant functional improvement in animal experiments. Here we report that significant improvement of locomotor function was achieved in rats with chronic spinal cord injury (SCI) by the application of combination treatments with tail nerve electrical stimulation (TANES), which can activate the central pattern generator, inducing active weight-supported stepping. Contusion injury (25 mm) to spinal cord T10 was produced by using the NYU impactor device in female, adult Long-Evans rats. Rats in 2 of 4 groups with SCI received basic treatments (scar ablation followed by transplantation of lamina propria of olfactory mucosa and cultured olfactory ensheathing cells into the lesion cavity) 6 weeks after SCI. Rats both with and without basic treatments were subjected to TANES one week after secondary surgery or 7 weeks after SCI. Sixteen weeks after secondary surgery or 22 weeks after SCI rats in two groups receiving TANES significantly improved their functional recovery compared with those without TANES, when evaluated with BBB open field rating scale (p<0.01). Among them, however, rats with basic treatments performed better than those without basic treatments. TANES may contribute to the activity-dependent plasticity below the injury level, which is critical for functional recovery. Additionally, TANES may promote axonal regeneration, including those from supraspinal level. Since TANES demonstrated considerable potential for achieving improvement of functional recovery in rat model, it would suggest a new strategy for chronic SCI.
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