Daily bilateral pudendal nerve electrical stimulation improves recovery from stress urinary incontinence

Contribution of pudendal nerve injury to stress urinary incontinence in a male rat model

Urinary incontinence is a common complication following radical prostatectomy, as the surgery disturbs critical anatomical structures. This study explored how pudendal nerve (PN) injury affects urinary continence in male rats. In an acute study, leak point pressure (LPP) and external urethral sphincter electromyography (EMG) were performed on six male rats with an intact urethra, the urethra exposed (UE), the PN exposed (NE), and after PN transection (PNT). In a chronic study, LPP and EMG were tested in 67 rats 4 days, 3 weeks, or 6 weeks after sham PN injury, PN crush (PNC), or PNT. Urethras were assessed histologically. Acute PNT caused a significant decrease in LPP and EMG amplitude and firing rate compared to other groups. PNC resulted in a significant reduction in LPP and EMG firing rate 4 days, 3 weeks, and 6 weeks later. EMG amplitude was also significantly reduced 4 days and 6 weeks after PNC. Neuromuscular junctions were less organized and less innervated after PNC or PNT at all timepoints compared to sham injured animals. Collagen infiltration was significantly increased after PNC and PNT compared to sham at all timepoints. This rat model could facilitate preclinical testing of neuroregenerative therapies for post-prostatectomy incontinence.

Exploring risk factors of pelvic organ prolapse at eastern of Democratic Republic of Congo: a case-control study

BACKGROUND

Pelvic organ prolapse is a common debilitating condition worldwide. Despite surgical treatment, its recurrence can reach up to 30%. It has multiple risk factors, some of which are particular for a low-resource settings. The identification these factors would help to devise risk models allowing the development of prevention policies. The objective of this study was to explore risk factors for pelvic organ prolapse in a population in eastern Democratic Republic of Congo (DRC).

METHODS

This was an unmatched case-control study conducted between January 2021 and January 2022. The sample size was estimated to be a total of 434 women (217 with prolapse as cases and 217 without prolapse as controls). Data comparisons were made using the Chi-Square and Student T tests. Binary and multivariate logistic regressions were used to determine associated factors. A p < 0.05 was considered significant.

RESULTS

Variables identified as definitive predictors of pelvic organ prolapse included low BMI (aOR 2.991; CI 1.419-6.307; p = 0.004), home birth (aOR 6.102; CI 3.526-10.561; p < 0.001), family history of POP (aOR 2.085; CI 1.107-3.924; p = 0.023), history of birth without an episiotomy (aOR 3.504; CI 2.031-6.048; p = 0), height ≤ 150 cm (aOR 5.328; CI 2.942-9.648; p < 0.001) and history of giving birth to a macrosomic baby (aOR 1.929; IC 1.121-3.321; p = 0.018).

CONCLUSIONS

This study identified that Body Mass Index and birth-related factors are definitive predictors of pelvic organ prolapse in a low-resource setting. These factors are potentially modifiable and should be targeted in any future pelvic organ prolapse prevention policy. Additionally, there seems to be a genetic predisposition for prolapse, which warrants further assessment in specifically designed large scale studies.

Neurobiological insights into lower urinary tract dysfunction: evaluating the role of brain-derived neurotrophic factor

Lower urinary tract dysfunction (LUTD) encompasses a range of debilitating conditions that affect both sexes and different age groups. Understanding the underlying neurobiological mechanisms contributing to LUTD has emerged as a critical avenue for the development of targeted therapeutic strategies. Brain-derived neurotrophic factor (BDNF), a prominent member of the neurotrophin family, has attracted attention due to its multiple roles in neural development, plasticity, and maintenance. This review examines the intricate interplay between neurobiological factors and LUTD, focusing on the central involvement of BDNF. The review emphasizes the bidirectional relationship between LUTD and BDNF and explores how LUTD-induced neural changes may affect BDNF dynamics and vice versa. Growth factor therapy and the combined administration of controlled release growth factors and stem cells are minimally invasive treatment strategies for neuromuscular injury. Among the many growth factors and cytokines, brain-derived neurotrophic factor (BDNF) plays a prominent role in neuromuscular repair. As an essential neurotrophin, BDNF is involved in the modulation of neuromuscular regeneration through tropomyosin receptor kinase B (TrkB). Increasing BDNF levels facilitates the regeneration of the external urethral sphincter and contributes to the regulation of bladder contraction. Treatments targeting the BDNF pathway and sustained release of BDNF may become novel treatment options for urinary incontinence and other forms of lower urinary tract dysfunction. This review discusses the applications of BDNF and the theoretical basis for its use in the treatment of lower urinary tract dysfunction, including urinary incontinence (UI), overactive bladder (OAB), and benign prostatic hyperplasia (BPH), and in the clinical diagnosis of bladder dysfunction.

Brain-Derived Neurotrophic Factor Is Indispensable to Continence Recovery after a Dual Nerve and Muscle Childbirth Injury Model

In women, stress urinary incontinence (SUI), leakage of urine from increased abdominal pressure, is correlated with pudendal nerve (PN) injury during childbirth. Expression of brain-derived neurotrophic factor (BDNF) is dysregulated in a dual nerve and muscle injury model of childbirth. We aimed to use tyrosine kinase B (TrkB), the receptor of BDNF, to bind free BDNF and inhibit spontaneous regeneration in a rat model of SUI. We hypothesized that BDNF is essential for functional recovery from the dual nerve and muscle injuries that can lead to SUI. Female Sprague-Dawley rats underwent PN crush (PNC) and vaginal distension (VD) and were implanted with osmotic pumps containing saline (Injury) or TrkB (Injury + TrkB). Sham Injury rats received sham PNC + VD. Six weeks after injury, animals underwent leak-point-pressure (LPP) testing with simultaneous external urethral sphincter (EUS) electromyography recording. The urethra was dissected for histology and immunofluorescence. LPP after injury and TrkB was significantly decreased compared to Injury rats. TrkB treatment inhibited reinnervation of neuromuscular junctions in the EUS and promoted atrophy of the EUS. These results demonstrate that BDNF is essential to neuroregeneration and reinnervation of the EUS. Treatments aimed at increasing BDNF periurethrally could promote neuroregeneration to treat SUI.

Perspectives on the Therapeutic Effects of Pelvic Floor Electrical Stimulation: A Systematic Review

Pelvic, perineal, and nervous lesions, which derive principally from pregnancy and childbirth, may lead to pelvic floor dysfunctions, such as organ prolapses and lesions in the nerves and muscles due to muscle expansion and physiology. It is estimated that 70% of women affected by this clinical picture have symptoms that do not respond to the classical treatments with antimuscarinic and anticholinergic drugs. Therefore, resorting to efficient alternatives and less invasive methods is necessary to assist this public health problem that predominantly affects the female population, which is more susceptible to the risk factors. This study aimed to perform an updated and comprehensive literature review focused on the effects of pelvic floor electrical stimulation, considering new perspectives such as a correlation between electric current and site of intervention and other molecular aspects, different from the present reviews that predominantly evaluate urodynamic aspects. For that purpose, PubMed and ScienceDirect databases were used to perform the search, and the Methodi ordinatio method was applied. With well-researched therapeutic effects, electrical stimulation induced promising results in histological, nervous, and molecular evaluations and spinal processes, which showed beneficial results and revealed new perspectives on ways to evoke responses in the lower urinary tract in a non-invasive way. Thus, it is possible to conclude that this type of intervention may be a non-invasive alternative to treat pelvic and perineal dysfunctions.

Brain-Derived Neurotrophic Factor Is an Important Therapeutic Factor in Mesenchymal Stem Cell Secretions for Treatment of Traumatic Peripheral Pelvic Injuries

Traumatic neuromuscular injury to the pudendal nerve and urethra during childbirth does not regenerate well and contributes to stress urinary incontinence in women. Mesenchymal stem cells (MSCs) can improve neuroregeneration via their secretions, or secretome, which includes brain-derived neurotrophic factor (BDNF). In this study, we investigated whether BDNF is a key factor in the secretome of MSCs for the facilitation of functional recovery following a dual simulated childbirth injury. BDNF knockdown (KD) MSCs were created using an anti-BDNF shRNA lentivirus vector. A scrambled sequence was used as a transduction control (scrambled). Cells were cultured for 24 h before media was concentrated 50x to create concentrated conditioned media (CCM) containing MSC secretome. CCM of unmanipulated MSCs was screened for high BDNF expression (high BDNF CCM). Concentrated control media (CM) was created by concentrating media not conditioned by cells. Female Sprague-Dawley rats underwent bilateral pudendal nerve crush and vaginal distension (Injury) or sham injury. One hour and 1 week after injury, sham injured rats received CM, and injured rats received CM, high BDNF CCM, KD CCM, or scrambled CCM (300 μl intraperitoneally). Three weeks after injury, rats underwent leak point pressure (LPP) and pudendal nerve sensory branch potential (PNSBP) recordings. The urethra and pudendal nerve were harvested for anatomical assessment. ANOVA followed by the Student-Newman-Keuls test determined significant differences between groups (p < 0.05). BDNF KD CCM had significantly decreased BDNF concentration compared to scrambled CCM, while the concentration in high BDNF CCM was significantly increased. LPP was significantly decreased in CM and KD CCM treated animals compared to sham injury, but not with scrambled or high BDNF CCM. PNSBP firing rate showed a significant decrease with CM treatment compared to sham injury. Neuromuscular junctions in the urethral sphincter in KD CCM, scrambled CCM, and high BDNF CCM were healthier than CM treated rats. While anatomical and nerve function tests demonstrate regeneration of the pudendal nerve with any CCM treatment, LPP results suggest it takes longer to recover continence with reduced BDNF in CCM. BDNF in MSC CCM is an important factor for the acceleration of recovery from a dual nerve and muscle injury.

Time course for urethral neuromuscular reestablishment and its facilitated recovery by transcutaneous neuromodulation after simulated birth trauma in rats

The aims of the study were to determine the time-course of urinary incontinence recovery after vaginal distension (VD), elucidate the mechanisms of injury from VD leading to external urethral sphincter (EUS) dysfunction, and assess if transcutaneous electrical stimulation (TENS) of the dorsal nerve of the clitoris facilitates recovery of urinary continence after VD. Rats underwent 4-h VD, 4-h sham VD (SH-VD), VD plus 1-h DNC TENS, and VD plus 1-h sham TENS (SH-TENS). TENS or SH-TENS were applied immediately and at days 2 and 4 post-VD. Micturition behavior, urethral histochemistry and histology, EUS and nerve electrophysiology, and cystometrograms were evaluated. VD induced urine leakage and significantly disrupted EUS fibers and nerve-conduction (VD vs SH-VD group;p < 0.01). Urine leakage disappeared 13 days post-VD (p < 0.001). Structural and functional recovery of EUS neuromuscular circuitry started by day 6 post-VD, but did not fully recover by day 11 post-VD (p > 0.05). TENS significantly decreased the frequency of urine leakage post-VD (days 5–7;p < 0.01). We conclude that rat urinary continence after VD requires 2 weeks to recover, although urethra structure is not fully recovered. TENS facilitated urinary continence recovery after VD. Additional studies are necessary to assess if TENS could be used in postpartum women.

Brain derived neurotrophic factor mediates accelerated recovery of regenerative electrical stimulation in an animal model of stress urinary incontinence

OBJECTIVE

Stress urinary incontinence (SUI) is prevalent among older women and can result from insufficient regeneration of the pudendal nerve (PN). Electrical stimulation (ES) of the PN upregulates brain derived neurotrophic factor (BDNF) and accelerates regeneration. Using tyrosine kinase B (TrkB) to reduce the availability of free BDNF, the aim of this study was to determine if BDNF is necessary for accelerated recovery via ES in a model of SUI.

METHODS

Our SUI model consists of Female Sprague-Dawley rats, whose PNs were crushed bilaterally twice for 30 s, followed by insertion of a modified Foley catheter into the vagina with balloon inflation for 4 h. These rats were divided into 4 groups: 1) Sham PN crush and sham vaginal distension without electrode implantation and with saline treatment (sham injury); 2) SUI with sham stimulation and saline treatment (SUI); 3) SUI and ES with saline treatment (SUI&ES); and 4) SUI and ES with TrkB treatment (SUI&ES&TrkB). Animals underwent ES or sham stimulation four times a week for two weeks. Four weeks after injury, animals underwent functional testing consisting of leak point pressure (LPP) with simultaneous external urethral sphincter (EUS) electromyography (EMG) and pudendal nerve recordings. Data was analyzed using ANOVA with Holm-Sidak posthoc test (p < 0.05). EUS and PN specimen were sectioned and stained to semi-quantitatively evaluate morphology, regeneration, and reinnervation.

RESULTS

LPP and EUS EMG firing rate were significantly increased in the sham injury and SUI&ES groups compared to the SUI and SUI&ES&TrkB groups. EUS of SUI rats showed few innervated neuromuscular junctions compared to sham injured rats, while both treatment groups showed an increase in reinnervated neuromuscular junctions.

CONCLUSION

ES accelerates functional recovery via a BDNF-mediated pathway in a model of SUI. These findings suggest ES could be used as a potential regenerative therapy for women with SUI.

Electroacupuncture for stress-predominant mixed urinary incontinence: a protocol for a three-armed randomised controlled trial

INTRODUCTION

Evidence specific for stress-predominant mixed urinary incontinence is still lacking at present, and acupuncture may relieve the symptoms. We plan to conduct this multi-centre, three-armed, randomised controlled trial to investigate the efficacy and safety of electroacupuncture among women with stress-predominant mixed urinary incontinence.

METHODS AND ANALYSIS

The trial will be conducted at five hospitals in China. Two hundred thirty-two eligible women will be randomly assigned (2:1:1) to the electroacupuncture, sham electroacupuncture or waiting-list group to receive either 24-session acupuncture/sham acupuncture treatment over 8 weeks and 24-week follow-up or 20-week watchful waiting. The primary outcome is the proportion of participants with at least 50% reduction in mean 24-hour stress incontinence episode frequencies from baseline to week 8. The outcome will be analysed with the intention to treatpopulation (defined as participants randomised) with a two-sided p value of less than 0.05 considered significant.

ETHICS AND DISSEMINATION

The protocol has been approved by Guang'anmen Hospital Institutional Review Board (2019-241-KY). Detailed information of the trial will be informed to the participants, and written informed consent will be obtained from every participant. Results of the trial are expected to be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT04299932).

Bioengineering in women's health: part I

This theme issue of Interface Focus is the first of two sets of articles on the topic of bioengineering in women's health. Although there is a long history of collaboration between engineers and medical professionals in orthopaedics and cardiovascular medicine, there has been growing interest in the last decade for interdisciplinary collaborations in other areas of medical science. This growth is particularly true in the case of women's health, a traditionally underserved area of research in the scientific community where fundamental knowledge of female physiology is still needed. Women's health is a broad category encompassing reproduction, fertility, maternal health, normal and abnormal pregnancy and the sequelae associated with a difficult childbirth. Women's health also includes sex-associated pathology associated with cancer, pain, cardiac disease, osteoporosis and other diseases. This list is not exhaustive with new scientific frontiers developing based on the evolving discourse of medicine for all. This first issue in the series focuses on bioengineering advances in the study of the non-pregnant woman, and the articles highlight important developments in pelvic floor disorders, biomedical devices, fertility, breast implant failure and breast cancer. The second issue in the series focuses on pregnancy.