Electrical stimulation enhances neuronal cell activity mediated by Schwann cell derived exosomes.

Electrical stimulation (ES) therapy has good effects in patients with nervous system injury-related diseases. ES promotes nerve cell regeneration and stimulates Schwann cells to express neurotrophic factors. The incidence of stress urinary incontinence (SUI) among elderly people is increasing. Some studies suggest that damage to the pudendal nerve is closely related to the pathogenesis of SUI. It has also been found that pelvic ES can reduce SUI symptoms in a rat model of SUI caused by pudendal nerve injury. Clinically, pelvic floor electrical stimulation is effective in patients with mild to moderate SUI. These studies indicate that ES may ameliorate damage to the pudendal nerve and thus achieve the goal of SUI treatment, although the mechanism of action of this treatment remains unclear. Therefore, the purpose of the present study was to clarify the relationships among ES, neural cells and Schwann cells at the cellular level. We applied ES to nerve cells at 100 mV/mm or 200 mV/mm for 0, 0.5, 1, or 2 h to investigate changes in nerve cell activity. We then co-cultured the nerve cells with Schwann cells to explore the influence of single-culture and co-culture conditions on the nerve cells. Compared to non-ES, ES of the nerve cells increased their activity. Compared to those in single culture, co-cultured nerve cells exhibited an additional increase in activity. We also found that Schwann cell derived exosomes could promote the activity of nerve cells, with glutamate and calcium ions playing a potential role in this process. These results suggest that the mutual regulation of neural cells and Schwann cells plays an important role in the process by which ES ameliorates neurological function, which may provide a basis for subsequent studies.

Electrical stimulation of the pudendal nerve promotes neuroregeneration and functional recovery from stress urinary incontinence in a rat model.

The pudendal nerve can be injured during vaginal delivery of children, and slowed pudendal nerve regeneration has been correlated with development of stress urinary incontinence (SUI). Simultaneous injury to the pudendal nerve and its target muscle, the external urethral sphincter (EUS), during delivery likely leads to slowed neuroregeneration. The goal of this study was to determine if repeat electrical stimulation of the pudendal nerve improves SUI recovery and promotes neuroregeneration in a dual muscle and nerve injury rat model of SUI. Rats received electrical stimulation or sham stimulation of the pudendal nerve twice weekly for up to 2 wk after injury. A separate cohort of rats received sham injury and sham stimulation. Expression of brain-derived neurotrophic factor (BDNF) and ßII-tubulin expression in Onuf's nucleus were measured 2, 7, and 14 days after injury. Urodynamics, leak point pressure (LPP), and EUS electromyography (EMG) were recorded 14 days after injury. Electrical stimulation significantly increased expression of BDNF at all time points and ßII-tubulin 1 and 2 wk after injury. Two weeks after injury, LPP and EUS EMG during voiding and LPP testing were significantly decreased compared with sham-injured animals. Electrical stimulation significantly increased EUS activity during voiding, although LPP did not fully recover. Repeat pudendal nerve stimulation promotes neuromuscular continence mechanism recovery possibly via a neuroregenerative response through BDNF upregulation in the pudendal motoneurons in this model of SUI. Electrical stimulation of the pudendal nerve may therefore improve recovery after childbirth and ameliorate symptoms of SUI by promoting neuroregeneration after injury.

Role of cannabinoid receptor type 1 in tibial and pudendal neuromodulation of bladder overactivity in cats.

The role of cannabinoid type 1 (CB1) receptors in tibial and pudendal neuromodulation of bladder overactivity induced by intravesical infusion of 0.5% acetic acid (AA) was determined in α-chloralose anesthetized cats. AA irritation significantly (P < 0.01) reduced bladder capacity to 36.6 ± 4.8% of saline control capacity. Tibial nerve stimulation (TNS) at two or four times threshold (2T or 4T) intensity for inducing toe movement inhibited bladder overactivity and significantly (P < 0.01) increased bladder capacity to 69.2 ± 9.7 and 79.5 ± 7.2% of saline control, respectively. AM 251 (a CB1 receptor antagonist) administered intravenously at 0.03 or 0.1 mg/kg significantly (P < 0.05) reduced the inhibition induced by 2T or 4T TNS, respectively, without changing the prestimulation bladder capacity. However, intrathecal administration of AM 251 (0.03 mg) to L7 spinal segment had no effect on TNS inhibition. Pudendal nerve stimulation (PNS) also inhibited bladder overactivity induced by AA irritation, but AM 251 at 0.01-1 mg/kg iv had no effect on PNS inhibition or the prestimulation bladder capacity. These results indicate that CB1 receptors play an important role in tibial but not pudendal neuromodulation of bladder overactivity and the site of action is not within the lumbar L7 spinal cord. Identification of neurotransmitters involved in TNS or PNS inhibition of bladder overactivity is important for understanding the mechanisms of action underlying clinical application of neuromodulation therapies for bladder disorders.

Both immediate and delayed intracavernous injection of autologous adipose-derived stromal vascular fraction enhances recovery of erectile function in a rat model of cavernous nerve injury.

BACKGROUND: Intracavernous injection of cultured adipose-derived stem cells (ADSCs) effectively restores erectile function in cavernous nerve (CN)-injured rats when administered at the time of injury. However, culturing exposes ADSCs to the risk of contamination and dedifferentiation. OBJECTIVE: Explore the effect of uncultured autologous adipose-derived stromal vascular fraction (SVF) on improving erectile function in a rat model of CN injury when administered at the time of injury or 4 wk after injury. DESIGN, SETTING, AND PARTICIPANTS: Eighty-nine male Sprague Dawley rats were randomly divided into four groups. CN injury or sham surgery was performed at the start of the study, and rats were treated with either SVF or vehicle. Functional testing and histologic analysis were performed 12 wk after CN crush or sham surgery. INTERVENTION: We used intracavernous injection of saline immediately after CN crush (n=23), intracavernous injection of SVF immediately after CN crush (n=17), intracavernous injection of SVF 4 wk after CN crush (n=23), or sham surgery (n=26). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We studied intracavernous pressure (ICP) response to CN electrostimulation and performed histologic examination of midpenile cross-sections. Data were analyzed using one-way analysis of variance followed by the Tukey-Kramer test. RESULTS AND LIMITATIONS: Both immediate and delayed treatment with SVF resulted in a significantly increased ICP-to-mean arterial pressure ratio compared with the vehicle-treated group. Both immediate and delayed treatment with SVF significantly increased expression of neuronal nitric oxide synthase and neurofilament in dorsal penile nerves compared to the vehicle group. Furthermore, the smooth muscle-to-collagen ratio within the corpus cavernosum was significantly improved in both of the SVF groups compared to vehicle-treated rats. The main limitation of the study is the lack of determination of the SVF components. CONCLUSIONS: Uncultured autologous SVF injected immediately or 4 wk after CN crush improved erectile function, promoted nerve regeneration, and prevented fibrosis of the corpus cavernosum following CN injury.

Recruitment of intracavernously injected adipose-derived stem cells to the major pelvic ganglion improves erectile function in a rat model of cavernous nerve injury.

BACKGROUND: Intracavernous (IC) injection of stem cells has been shown to ameliorate cavernous-nerve (CN) injury-induced erectile dysfunction (ED). However, the mechanisms of action of adipose-derived stem cells (ADSC) remain unclear. OBJECTIVES: To investigate the mechanism of action and fate of IC injected ADSC in a rat model of CN crush injury. DESIGN, SETTING, AND PARTICIPANTS: Sprague-Dawley rats (n=110) were randomly divided into five groups. Thirty-five rats underwent sham surgery and IC injection of ADSC (n=25) or vehicle (n=10). Another 75 rats underwent bilateral CN crush injury and were treated with vehicle or ADSC injected either IC or in the dorsal penile perineural space. At 1, 3, 7 (n=5), and 28 d (n=10) postsurgery, penile tissues and major pelvic ganglia (MPG) were harvested for histology. ADSC were labeled with 5-ethynyl-2-deoxyuridine (EdU) before treatment. Rats in the 28-d groups were examined for erectile function prior to tissue harvest. MEASUREMENTS: IC pressure recording on CN electrostimulation, immunohistochemistry of the penis and the MPG, and number of EdU-positive (EdU+) cells in the injection site and the MPG. RESULTS AND LIMITATIONS: IC, but not perineural, injection of ADSC resulted in significantly improved erectile function. Significantly more EdU+ ADSC appeared in the MPG of animals with CN injury and IC injection of ADSC compared with those injected perineurally and those in the sham group. One day after crush injury, stromal cell-derived factor-1 (SDF-1) was upregulated in the MPG, providing an incentive for ADSC recruitment toward the MPG. Neuroregeneration was observed in the group that underwent IC injection of ADSC, and IC ADSC treatment had beneficial effects on the smooth muscle/collagen ratio in the corpus cavernosum. CONCLUSIONS: CN injury upregulates SDF-1 expression in the MPG and thereby attracts intracavernously injected ADSC. At the MPG, ADSC exert neuroregenerative effects on the cell bodies of injured nerves, resulting in enhanced erectile response.