Autologous bone-marrow-derived mesenchymal stem cell transplantation into injured rat urethral sphincter

Exosomes derived from mesenchymal stromal cells: a promising treatment for pelvic floor dysfunction

Pelvic floor dysfunction (PFDs), which include pelvic organ prolapse (POP), stress urinary incontinence (SUI) and anal incontinence (AI), are common degenerative diseases in women that have dramatic effects on quality of life. The pathology of PFDs is based on impaired pelvic connective tissue supportive strength due to an imbalance in extracellular matrix (ECM) metabolism, the loss of a variety of cell types, such as fibroblasts, muscle cells, peripheral nerve cells, and oxidative stress and inflammation in the pelvic environment. Fortunately, exosomes, which are one of the major secretions of mesenchymal stromal cells (MSCs), are involved in intercellular communication and the modulation of molecular activities in recipient cells via their contents, which are bioactive proteins and genetic factors such as mRNAs and miRNAs. These components modify fibroblast activation and secretion, facilitate ECM modelling, and promote cell proliferation to enhance pelvic tissue regeneration. In this review, we focus on the molecular mechanisms and future directions of exosomes derived from MSCs that are of great value in the treatment of PFD.

Stem cell therapy combined with controlled release of growth factors for the treatment of sphincter dysfunction

Sphincter dysfunction often occurs at the end of tubule organs such as the urethra, anus, or gastroesophageal sphincters. It is the primary consequence of neuromuscular impairment caused by trauma, inflammation, and aging. Despite intensive efforts to recover sphincter function, pharmacological treatments have not achieved significant improvement. Cell- or growth factor-based therapy is a promising approach for neuromuscular regeneration and the recovery of sphincter function. However, a decrease in cell retention and viability, or the short half-life and rapid degradation of growth factors after implantation, remain obstacles to the translation of these therapies to the clinic. Natural biomaterials provide unique tools for controlled growth factor delivery, which leads to better outcomes for sphincter function recovery in vivo when stem cells and growth factors are co-administrated, in comparison to the delivery of single therapies. In this review, we discuss the role of stem cells combined with the controlled release of growth factors, the methods used for delivery, their potential therapeutic role in neuromuscular repair, and the outcomes of preclinical studies using combination therapy, with the hope of providing new therapeutic strategies to treat incontinence or sphincter dysfunction of the urethra, anus, or gastroesophageal tissues, respectively.

Comparison of the differentiation abilities of bone marrow-derived mesenchymal stem cells and adipose-derived mesenchymal stem cells toward nucleus pulposus-like cells in three-dimensional culture

Nucleus pulposus cell (NPC) transplantation can be a potential therapeutic approach for intervertebral disc degeneration (IDD). However, low cell viability has restricted the therapeutic capacity of NPCs, and sources of natural NPCs are limited. Bone marrow-derived mesenchymal stem cells (BMSCs) and adipose-derived mesenchymal stem cells (ADSCs) can be differentiated toward NPC-like cells. However, it is unknown whether there are differences in the abilities of these two cell types to differentiate into NPC-like cells, or which cell type exhibits the best differentiation ability. The present study compared the abilities of BMSCs and ADSCs to differentiate toward NPC-like cells with or without a 3D culture system to lay a foundation for stem cell transplantation therapy for IDD. BMSCs were isolated from the rat whole bone marrow cell using the repeated adherent culture method. ADSCs were isolated from rat adipose tissues in the subcutaneous inguinal region using the enzyme digestion method. Cells were identified using flow cytometry. Cell viability was assessed via Cell Counting Kit-8 assays, and reverse transcription-quantitative PCR and western blotting were carried out to evaluate the expression of NPC markers and chondrocyte-specific genes. Glycosaminoglycans (GAGs) and proteoglycans were examined via Alcian blue and safranin O staining, respectively. ADSCs in 3D culture displayed the highest cell proliferative ability, compared with the 2D culture system and BMSC culture. In addition, ADSCs in 3D culture exhibited increased GAG and proteoglycan synthesis than BMSCs. Compared with BMSCs in 3D culture, ADSCs in 3D culture exhibited higher mRNA and protein expression of NPC marker genes (hypoxia-inducible factor 1-α, glucose transporter 1) and chondrocyte-specific genes (Sox-9, aggrecan and type II collagen). The present findings indicated that ADSCs exhibited a better ability to differentiate into NPC-like cells in 3D culture compared with BMSCs, which may be of value for the regeneration of intervertebral discs using cell transplantation therapy.

Bone marrow stem cells secretome accelerates simulated birth trauma-induced stress urinary incontinence recovery in rats

Stress urinary incontinence (SUI) is defined as involuntary urine leakage during physical activities that increase the intra-abdominal pressure on the bladder. We studied bone marrow stem cell (BMSC) secretome-induced activation of anterior vaginal wall (AVW) fibroblasts and its ability to accelerate SUI recovery following vaginal distention (VD) in a rat model of birth trauma using BMSC-conditioned medium (BMSC-CM) and concentrated conditioned medium (CCM). BMSC-CM enhanced the proliferation, migration, and collagen synthesizing abilities of fibroblasts. Differentially expressed genes in BMSC-CM-induced fibroblasts were mainly enriched for cell adhesion, extracellular fibril organization and angiogenesis. Treatment with the JAK2 inhibitor AG490 reversed BMSC-CM-induced activation of the JAK2/STAT4 pathway. Periurethral injection with BMSC-CCM markedly enhanced the abdominal leak point pressure (LPP) in rats after VD. Histological analysis revealed increased numbers of fibroblasts, improved collagen fibers arrangement and elevated collagens content in the AVW of rats receiving BMSC-CCM. These findings suggest the BMSC secretome activates AVW fibroblasts and contributes to the functional and anatomic recovery of simulated birth trauma-induced SUI in rats.

Magnetic targeting of super-paramagnetic iron oxide nanoparticle labeled myogenic-induced adipose-derived stem cells in a rat model of stress urinary incontinence

Cell-based injectable therapy utilizing stem cells is a promising approach for the treatment of stress urinary incontinence (SUI). Applying a magnetically controlled cell delivery approach has enormous potential to enhance cell retention capability within the specified site. To assess the therapeutic efficacy of cellular magnetic targeting, we applied an external magnetic force to target an adipose-derived stem cell based therapy in a rat model of SUI. The results revealed that magnetic attraction of transplanted cells under the magnetic field was generated by cell uptake of superparamagnetic iron oxide nanoparticles in vitro. More importantly, magnetic targeting improved the retention rate of transplanted cells and facilitated the restoration of sphincter structure and function in a rat SUI model according to the results of histological examination and urodynamic testing. Therefore, magnetically guided targeting strategy might be a potential therapy method for treatment of SUI.

Regenerative medicine and injection therapies in stress urinary incontinence

Stress urinary incontinence (SUI) is a common and bothersome condition. Anti-incontinence surgery has high cure rates, but concerns about mesh tapes have resulted in the resurgence of surgical procedures that involve increased abdominopelvic dissection and morbidity. Injection therapy with urethral bulking agents or stem cell formulations have been developed as minimally invasive alternatives. Many synthetic and biological bulking agents have been trialled, but several have been discontinued owing to safety concerns. The use of Macroplastique and Contigen has the largest evidence base, but, overall, success rates seem to be similar between the various agents and positive outcomes are poorly sustained for more than 6 months. Furthermore, subjective cure rates, although initially high, also deteriorate over time. The available data consistently demonstrate manifestly poorer outcomes for injection therapies than for surgery. Stem cell treatments are thought to functionally regenerate the urethral sphincter in patients with suspected intrinsic sphincter deficiency. Autologous adipose and muscle-derived stem cells seem to be the intuitive cell source, as they are comparatively abundant, can be harvested and cause minimal donor site morbidity. To date, only a few small clinical studies have been reported and most data are derived from animal models. The success rates of stem cell injection therapies seem to be comparable with those of bulking agents.

Microenergy acoustic pulses induced myogenesis of urethral striated muscle stem/progenitor cells

Background

Stress urinary incontinence (SUI) is a common disorder with high prevalence in women across their life span, but there are no non-surgical curative options for the condition. Stem cell-based therapy, especially endogenous stem cell therapy may be a potential treatment method for SUI. The aims of this study are to identify, isolate, and assay the function of urethral striated muscle derived stem/progenitor cells (uMDSCs) and to assess uMDSC response to microenergy acoustic pulses (MAP).

Methods

Urethral striated muscle was identified utilizing 3D imaging of solvent organs (3DISCO) and immunofluorescence (IF). uMDSCs were isolated and purified from Zucker Lean (ZL) (ZUC-LEAN) (ZUC-Leprfa 186) rats, with magnetic-activated cell sorting (MACS) and pre-plating methods. The stemness and differentiation potential of the uMDSCs were measured by cell proliferation, EdU, flow cytometry, IF, and Western blot.

Results

Comparison of the cell proliferation assays between MACS and pre-plating reveals the advantage of MACS over pre-plating. In addition, the study reveals that uMDSCs form myotubes when treated with MAP.

Conclusions

The uMDSCs within female rat urethral striated muscle could be a therapeutic target of MAP in managing SUI.

Systemically transplanted mesenchymal stem cells induce vascular-like structure formation in a rat model of vaginal injury

The beneficial effect of mesenchymal stem cells (MSCs) on wound healing is mostly attributed to a trophic effect that promotes angiogenesis. Whether MSCs can contribute to the formation of new blood vessels by direct differentiation is still controversial. Pelvic floor dysfunction (PFD) is a group of disorders that negatively affect the quality of women's lives. Traditional vaginal surgical repair provides disappointing anatomical outcome. Stem cell transplantation may be used to supplement surgery and improve its outcome. Here we aimed to examine the engraftment, survival, differentiation and angiogenic effect of transplanted MSCs in a vaginal injury rat model. MSCs were obtained from the bone marrow of Sprague Drawley (SD) rats, expanded and characterized in vitro. The MSCs expressed CD90 and CD29, did not express CD45, CD34, CD11b and CD31 and could differentiate into osteogenic, chondrogenic and adipogenic lineages. Cells were labeled with either PKH-26 or GFP and transplanted systemically or locally to female SD rats, just after a standardized vaginal incision was made. Engraftment after local transplantation was less efficient at all-time points compared to systemic administration. In the systemically transplanted animal group, MSCs migrated to the injury site and were present in the healed vagina for at least 30 days. Both systemic and local MSCs transplantation promoted host angiogenesis. Systemically transplanted MSCs created new vascular-like structures by direct differentiation into endothelium. These findings pave the way to further studies of the potential role of MSCs transplantation in improving surgical outcome in women with PFD.

Applicability of regenerative medicine and tissue engineering for the treatment of stress urinary incontinence in female patients

Stress urinary incontinence (SUI) is an age health-related issue that generates interest due to its considerable public health burden and the controversies surrounding treatment. It is highly prevalent affecting 30-40% of all women during their lifetime. Midurethral slings are the standard of gold standard treatment for female patients with SUI. They have excellent short-term cure rates; however, their efficacy tends to decrease over time and patients often report urinary incontinence recurrence. This paper addresses the applicability of regenerative medicine and tissue engineering for the treatment of SUI in female patients. Cell-based treatment with periurethral injection of autologous adipose or muscle-derived stem cells have been used for SUI; however, the cure rates and SUI recurrence at 1 year were 40% and 70%, respectively. Novel minimally invasive approaches, such as low-intensity extracorporeal shock wave therapies have shown promising results in SUI animal models. In addition, local injection of growth factors, chemokines, and specific antibodies have shown histological evidence of neoangiogenesis, nerve, and sphincter regeneration in rodents and nonhuman primates with SUI. The use of bioactive factors and proteins secreted by cells, which is called secretomes, have been recognized as key regulators of various mechanisms, such as immunomodulation, angiogenesis, inflammation, apoptosis, and tissue repair. Emerging therapies aiming to replace or restore tissues and organ functionality may improve the long-term efficacy and in the near future may represent the standard of care for the treatment of SUI.

Advances in stem cell therapy for male stress urinary incontinence

INTRODUCTION

Among the several options that have been proposed in recent years for the management of male stress urinary incontinence (SUI), stem cell therapy represents a new frontier in treatment. The aim of this paper is to update the current status of stem cell therapy in animal and human studies for the management of iatrogenic male SUI.

AREAS COVERED

A literature review was conducted based on MEDLINE/PubMed searches for English articles using a combination of the following keywords: stem cell therapy, urinary incontinence, prostatectomy, regenerative medicine, mesenchymal stem cells.

EXPERT OPINION

The few studies reported in the literature have demonstrated short-term safety and promising results of stem cell therapy in treating male SUI. However, many aspects need to be clarified before stem cell therapy can be introduced into daily urologic practice. In fact, important issues such as the limitations of these studies in terms of small sample sizes and short follow-ups, the incomplete knowledge of the mechanism of action of stem cells, the technical details regarding the delivery method and the best sources of stem cells, the safety risks regarding genomic or epigenetic changes and potential immune reactions in the longer term need to be identified in more stringent clinical trials.

Efficiency of mesenchymal stem cells in treatment of urinary incontinence: a systematic review on animal models

AIM

In recent years, the administration of stem cells has been considered a new option for treatment of urinary incontinence (UI). In the present study, the efficiency of mesenchymal stem cell (MSC) transplantation in the treatment of UI was evaluated.

METHODS

Combinations of the key words 'mesenchymal stem cells', 'MSCs', 'urinary incontinence', 'urethral sphincter' and 'involuntary urination' were searched in PubMed and Science Direct databases. Following application of exclusion criteria to the 1946 papers obtained and review and duplicate articles were removed, 23 articles were considered further. The search was limited to the animal model studies.

RESULTS

The data obtained from the evaluation of different studies indicated that the injected MSCs play an important role in the neovascularization and the recovery of muscle cells in UI models through the paracrine process.

CONCLUSION

The obtained data suggested that further trials are needed to be focused on clinical phase of MSC therapy on the patients affected by UI.

Human Urine-Derived Stem Cell Differentiation to Endothelial Cells with Barrier Function and Nitric Oxide Production

Endothelial cells (ECs) play a key role in revascularization within regenerating tissue. Stem cells are often used as an alternative cell source when ECs are not available. Several cell types have been used to give rise to ECs, such as umbilical cord vessels, or differentiated from somatic stem cells, embryonic, or induced pluripotent stem cells. However, the latter carry the potential risk of chronic immune rejection and oncogenesis. Autologous endothelial precursors are an ideal resource, but currently require an invasive procedure to obtain them from the patient's own blood vessels or bone marrow. Thus, the goal of this study was to determine whether urine-derived stem cells (USCs) could differentiate into functional ECs in vitro. Urine-derived cells were then differentiated into cells of the endothelial lineage using endothelial differentiation medium for 14 days. Changes in morphology and ultrastructure, and functional endothelial marker expression were assessed in the induced USCs in vitro. Grafts of the differentiated USCs were then subcutaneously injected into nude mice. Induced USCs expressed significantly higher levels of specific markers of ECs (CD31, vWF, eNOS) in vitro and in vivo, compared to nondifferentiated USCs. In addition, the differentiated USC formed intricate tubular networks and presented similar tight junctions, and migration and invasion ability, as well as ability to produce nitric oxide (NO) compared to controls. Using USCs as autologous EC sources for vessel, tissue engineering strategies can yield a sufficient number of cells via a noninvasive, simple, and low-cost method suitable for rapid clinical translation. Stem Cells Translational Medicine 2018 Stem Cells Translational Medicine 2018;7:686-698.

Effects of electroacupuncture combined with stem cell transplantation on anal sphincter injury-induced faecal incontinence in a rat model

BACKGROUND

Bone marrow mesenchymal stem cells (BMSCs) and acupuncture are known to mitigate tissue damage. This study aimed to investigate the therapeutic effects of combined electroacupuncture (EA) stimulation and BMSC injection in a rat model of anal sphincter injury-induced faecal incontinence (FI).

METHODS

60 Sprague-Dawley rats were randomly divided into five groups: sham-operated control, FI, FI+EA, FI+BMSC, and FI+BMSC+EA. The anorectal tissues were collected on days 1, 3, 7 and 14. Repair of the injured anal sphincter was compared using haematoxylin and eosin (HE) and immunocytochemiscal analyses with sarcomeric α actinin. The expression of stromal cell derived factor-1 (SDF-1) and monocyte chemoattractant protein-3 (MCP-3) was detected by quantitative reverse transcription PCR to evaluate the effects of EA on the homing of BMSCs.

RESULTS

The therapeutic effect of combined EA+BMSCs on damaged tissue was the strongest among all the groups as indicated by HE and immunohistochemical staining. The expression of SDF-1 and MCP-3 was significantly increased by combined EA and BMSC treatment when compared with the other groups (P=0.01 to P<0.05), suggesting promotive effects of EA on the homing of BMSCs.

CONCLUSION

The combination of EA and BMSC transplantation effectively repaired the impaired anal sphincters. The underlying mechanism might be associated with apparent promotive effects of EA on the homing of BMSCs. Our study provides a theoretical basis for the development of a non-surgical treatment method for FI secondary to muscle impairment.

Purified Human Skeletal Muscle-Derived Stem Cells Enhance the Repair and Regeneration in the Damaged Urethra

BACKGROUND

Postoperative damage of the urethral rhabdosphincter and nerve-vascular networks is a major complication of radical prostatectomy and generally causes incontinence and/or erectile dysfunction. The human skeletal muscle-derived stem cells, which have a synchronized reconstitution capacity of muscle-nerve-blood vessel units, were applied to this damage.

METHODS

Cells were enzymatically extracted from the human skeletal muscle, sorted using flow cytometry as CD34/45 (Sk-34) and CD29/34/45 (Sk-DN/29) fractions, and separately cultured/expanded in appropriate conditions within 2 weeks. Urethral damage was induced by manually removing one third of the wall of the muscle layer in nude rats. A mixture of expanded Sk-34 and Sk-DN/29 cells was applied on the damaged portion for the cell transplantation (CT) group. The same amount of media was used for the non-CT (NT) group. Urethral pressure profile was evaluated via electrical stimulation to assess functional recovery. Cell engraftments and differentiations were detected using immunohistochemistry and immunoelectron microscopy. Expression of angiogenic cytokines was also analyzed using reverse transcriptase-polymerase chain reaction and protein array.

RESULTS

At 6 weeks after transplantation, the CT group showed a significantly higher functional recovery than the NT group (70.2% and 39.1%, respectively; P < 0.05). Histological analysis revealed that the transplanted human cells differentiated into skeletal muscle fibers, nerve-related Schwann cells, perineuriums, and vascular pericytes. Active paracrine angiogenic cytokines in the mixed cells were also detected with enhanced vascular formation in vivo.

CONCLUSIONS

The transplantation of Sk-34 and Sk-DN/29 cells is potentially useful for the reconstitution of postoperative damage of the urethral rhabdosphincter and nerve-vascular networks.

Periurethral muscle-derived mononuclear cell injection improves urethral sphincter restoration in rats

AIMS

Investigate the effect of a novel cell-based therapy with skeletal muscle-derived mononuclear cells (SMDMCs) in a rat model of stress urinary incontinence.

METHODS

Male Wistar-Kyoto rats' hind limb muscles were enzymatically dissociated, and SMDMCs were isolated without needing expansion. The cell population was characterized. Twenty female rats underwent urethrolysis. One week later, 10 rats received periurethral injection of 10⁶ cells (SMDMC group), and 10 rats received saline injections (Saline group). Ten rats underwent sham surgery (Sham group). Four weeks after injection, animals were euthanized and the urethra was removed. The incorporation of SMDMCs in the female urethra was evaluated with fluorescence in situ hybridization for the detection of Y-chromosomes. Hematoxylin and eosin, Masson's trichrome staining, and immunohistochemistry for actin and myosin were performed. The muscle/connective tissue, actin and myosin ratios were calculated. Morphological evaluation of the urethral diameters and fractional areas of the lumen, mucosa, and muscular layer was performed.

RESULTS

SMDMCs population was consistent with the presence of muscle cells, muscle satellite cells, perivascular cells, muscle progenitor cells, and endothelial cells. SMDMCs were incorporated into the urethra. A significant decrease in the muscle/connective tissue ratio was observed in the Saline group compared with the SMDMC and Sham groups. The proportions of actin and myosin were significantly decreased in the Saline group. No differences were observed in the morphometric parameters.

CONCLUSIONS

SDMSC were incorporated into the rat urethra and promoted histological recovery of the damaged urethral sphincter, resulting in decreased connective tissue deposition and increased muscle content.

The Anatomy of Caprine Female Urethra and Characteristics of Muscle and Bone Marrow Derived Caprine Cells for Autologous Cell Therapy Testing

Cell therapy is emerging as an alternative treatment of stress urinary incontinence. However, many aspects of the procedure require further optimization. A large animal model is needed to reliably test cell delivery methods. In this study, we aim to determine suitability of the goat as an experimental animal for testing intraurethral autologous cell transplantation in terms of urethral anatomy and cell culture parameters. The experiments were performed in 12 mature/aged female goats. Isolated caprine muscle derived cells (MDC) were myogenic in vitro and mesenchymal stem cells (MSC) population was able to differentiate into adipo-, osteo- and chondrogenic lineages. The median yield of cells after 3 weeks of culture amounted 47 × 10(6) for MDC and 37 × 10(6) for MSC. Urethral pressure profile measurements revealed the mean functional urethral length of 3.75 ± 0.7 cm. The mean maximal urethral closure pressure amounted 63.5 ± 5.9 cmH₂ O and the mean functional area was 123.3 ± 19.4 cm*cmH₂ O. The omega- shaped striated urethral sphincter was well developed in the middle and distal third of the urethra and its mean thickness on cross section was 2.3 mm. In the proximal part of the urethra only loosely arranged smooth muscle fibers were identified. To conclude, presented data demonstrate that caprine MDC and MSC can be expanded in vitro in a repeatable manner even when mature or aged animals are cell donors. Results suggest that female caprine urethra has similar parameters to those reported in human and therefore the goat can be an appropriate experimental animal for testing intraurethral cell transplantation. Anat Rec, 00:000-000, 2016. © 2016 Wiley Periodicals, Inc. Anat Rec, 300:577-588, 2017. © 2016 Wiley Periodicals, Inc.

Adipose-Derived Regenerative Cell Injection Therapy for Postprostatectomy Incontinence: A Phase I Clinical Study

PURPOSE

We report our initial experience with transurethral injection of autologous adipose-derived regenerative cells (ADRCs) for the treatment of urinary incontinence after radical prostatectomy.

MATERIALS AND METHODS

After providing written informed consent, six men with persistent urinary incontinence after radical prostatectomy were enrolled in the study. Under general anesthesia, about 50 mL of adipose tissue was obtained from the patients by liposuction. ADRCs were obtained by separation with centrifugation using the Celution cell-processing device. A mixture of ADRCs and adipose tissue were transurethrally injected into the submucosal space of the membranous urethra. Functional and anatomical improvement was assessed using a 24-h pad test, validated patient questionnaire, urethral pressure profile, and magnetic resonance imaging (MRI) during 12-week follow-up.

RESULTS

Urine leakage volume was improved with time in all patients in the 24-h pad test, with the exemption of temporal deterioration at the first 2 weeks post-injection in 2 patients. Subjective symptoms and quality of life assessed on the basis of questionnaire results showed similar improvement. The mean maximum urethral closing pressure increased from 44.0 to 63.5 cm H₂O at 12 weeks after injection. MRI showed an increase in functional urethral length (from 6.1 to 8.3 mm) between the lower rim of the pubic bone and the bladder neck. Adverse events, such as pelvic pain, inflammation, or de novo urgency, were not observed in any case during follow-up.

CONCLUSION

This study demonstrated that transurethral injection of autologous ADRCs can be a safe and effective treatment modality for postprostatectomy incontinence.

Regenerative Medicine Therapies for Stress Urinary Incontinence

PURPOSE

We summarize the current state of knowledge regarding cell therapy for stress urinary incontinence and introduce new approaches of using regenerative pharmacology as an adjunct or replacement for cell therapy.

MATERIALS AND METHODS

We reviewed the literature by searching PubMed®, Ovid and Biological Abstracts. The period searched was 1975 to December 2015. The inclusion terms separately or in combination were stress urinary incontinence, cell therapy, chemokine, vascularization, innervation, secretome and/or animal models. Epublished articles were not included. We did not exclude articles based on impact factor.

RESULTS

Cell therapy is currently proposed to restore functional muscle cells and aid in closure of the sphincter in women with sphincter associated incontinence. Clinical trials have included small numbers of patients and results have varied depending on the patient cohorts and the cells used. Results of preclinical studies have also varied but show a more favorable outcome. This difference was most likely explained by the fact that animal modeling is not directly translatable to the human condition. However, preclinical studies have identified an exciting new approach to regeneration of the urinary sphincter using the components of cells (secretomes) or chemokines that home reparative cells to sites of injury.

CONCLUSIONS

Cell therapy will continue to be explored. However, a regenerative pharmacological approach to the treatment of stress urinary incontinence holds the promise of bypassing the lengthy and expensive process of cell isolation and also increasing the availability of treatment in many clinical settings. This approach requires careful preclinical modeling and attention to its health benefit-to-risk ratio.

Stem Cell Therapy for Male Urinary Incontinence

INTRODUCTION

Among the medical and surgical options which have been proposed in the last years for the management of male stress urinary incontinence (SUI), stem cell therapy represents a new frontier treatment. The aim of this paper is to update the current status of stem cell therapy in animal and human studies for the management of iatrogenic male SUI.

MATERIAL AND METHODS

A PubMed review of the literature on stem cell therapy for the treatment of male SUI was performed.

RESULTS

Regarding animal studies, bone marrow-, muscle- and adipose-derived stem cells have been widely studied, showing regeneration of the urethral sphincter and recovery of the damaged pelvic nerves. With regard to human studies, only four papers are available in the literature using muscle- and adipose-derived stem cells which reported a significant improvement in sphincteric function and incontinence with no severe side effects.

CONCLUSIONS

In spite of these promising results, further studies are needed with longer follow-ups and larger numbers of patients in order to clarify the potential role of stem cell therapy for the treatment of male SUI.

Stem Cell Therapy for Treatment of Stress Urinary Incontinence: The Current Status and Challenges

Stress urinary incontinence (SUI) is a common urinary system disease that mostly affects women. Current treatments still do not solve the critical problem of urethral sphincter dysfunction. In recent years, there have been major developments in techniques to obtain, culture, and characterize autologous stem cells as well as many studies describing their applications for the treatment of SUI. In this paper, we review recent publications and clinical trials investigating the applications of several stem cell types as potential treatments for SUI and the underlying challenges of such therapy.

Mesenchymal stem cell therapy in a rat model of birth-trauma injury: functional improvements and biodistribution

INTRODUCTION AND HYPOTHESIS

We evaluated the potential role of human mesenchymal stem cells (hMSCs) in improvement of urinary continence following birth-trauma injury.

METHODS

Human MSCs were injected periurethrally or systemically into rats immediately after vaginal distention (VD) (n = 90). Control groups were non-VD (uninjured/untreated, n = 15), local or systemic saline (injection/control, n = 90), and dermofibroblast (cell therapy/control, n = 90). Leak-point pressure (LPP) was measured 4, 10, and 14 days later. Urethras were morphometrically evaluated. In another sets of VD and non-VD rats, the fate of periurethrally injected hMSC, biodistribution, and in vivo viability was studied using human Alu genomic repeat staining, PKH26 labeling, and luciferase-expression labeling, respectively.

RESULTS

Saline- and dermofibroblast-treated control rats demonstrated lower LPP than non-VD controls at days 4 and 14 (P < 0.01). LPP after systemic hMSC and periurethral hMSC treatment were comparable with non-VD controls at 4, 10, and 14 days (P > 0.05). Local saline controls demonstrated extensive urethral tissue bleeding. The connective tissue area/urethral section area proportion and vascular density were higher in the local hMSC- versus the saline-treated group at 4 and 14 days, respectively. No positive Alu-stained nuclei were observed in urethras at 4, 10, and 14 days. PKH26-labelled cells were found in all urethras at 2 and 24 h. Bioluminescence study showed increased luciferase expression from day 0 to 1 following hMSC injection.

CONCLUSIONS

Human MSCs restored the continence mechanism with an immediate and sustained effect in the VD model, while saline and dermofibroblast therapy did not. Human MSCs remained at the site of periurethral injection for <7 days. We hypothesize that periurethral hMSC treatment improves vascular, connective tissue, and hemorrhage status of urethral tissues after acute VD injury.

Viability and MR detectability of iron labeled mesenchymal stem cells used for endoscopic injection into the porcine urethral sphincter

Direct stem cell therapies for functionally impaired tissue require a sufficient number of cells in the target region and a method for verifying the fate of the cells in the subsequent time course. In vivo MRI of iron labeled mesenchymal stem cells has been suggested to comply with these requirements. The study was conducted to evaluate proliferation, migration, differentiation and adhesion effects as well as the obtained iron load of an iron labeling strategy for mesenchymal stem cells. After injection into the porcine urethral sphincter, the labeled cells were monitored for up to six months using MRI. Mesenchymal stem cells were labeled with ferucarbotran (60/100/200 µg/mL) and ferumoxide (200 µg/mL) for the analysis of migration and viability. Phantom MR measurements were made to evaluate effects of iron labeling. For short and long term studies, the iron labeled cells were injected into the porcine urethral sphincter and monitored by MRI. High resolution anatomical images of the porcine urethral sphincter were applied for detection of the iron particles with a turbo-spin-echo sequence and a gradient-echo sequence with multiple TE values. The MR images were then compared with histological staining. The analysis of cell function after iron labeling showed no effects on proliferation or differentiation of the cells. Although the adherence increases with higher iron dose, the ability to migrate decreases as a presumed effect of iron labeling. The iron labeled mesenchymal stem cells were detectable in vivo in MRI and histological staining even six months after injection. Labeling with iron particles and subsequent evaluation with highly resolved three dimensional data acquisition allows sensitive tracking of cells injected into the porcine urethral sphincter for several months without substantial biological effects on mesenchymal stem cells.

Cell Therapy for Stress Urinary Incontinence

Urinary incontinence (UI) is the involuntary loss of urine and is a common condition in middle-aged and elderly women and men. Stress urinary incontinence (SUI) is caused by leakage of urine when coughing, sneezing, laughing, lifting, and exercise, even standing leads to increased intra-abdominal pressure. Other types of UI also exist such as urge incontinence (also called overactive bladder), which is a strong and unexpected sudden urge to urinate, mixed forms of UI that result in symptoms of both urge and stress incontinence, and functional incontinence caused by reduced mobility, cognitive impairment, or neuromuscular limitations that impair mobility or dexterity. However, for many SUI patients, there is significant loss of urethral sphincter muscle due to degeneration of tissue, the strain and trauma of pregnancy and childbirth, or injury acquired during surgery. Hence, for individuals with SUI, a cell-based therapeutic approach to regenerate the sphincter muscle offers the advantage of treating the cause rather than the symptoms. We discuss current clinically relevant cell therapy approaches for regeneration of the external urethral sphincter (striated muscle), internal urethral sphincter (smooth muscle), the neuromuscular synapse, and blood supply. The use of mesenchymal stromal/stem cells is a major step in the right direction, but they may not be enough for regeneration of all components of the urethral sphincter. Inclusion of other cell types or biomaterials may also be necessary to enhance integration and survival of the transplanted cells.

Prospects of stem cell treatment in benign urological diseases

Stem cells (SCs) are undifferentiated cells that are capable of self-renewal and differentiation and that therefore contribute to the renewal and repair of tissues. Their capacity for division, differentiation, and tissue regeneration is highly dependent on the surrounding environment. Several preclinical and clinical studies have utilized SCs in urological disorders. In this article, we review the current status of SC use in benign urological diseases (erectile dysfunction, Peyronie disease, infertility, and urinary incontinence), and we summarize the results of the preclinical and clinical trials that have been conducted.

Dynamic reciprocity in cell-scaffold interactions

Tissue engineering in urology has shown considerable promise. However, there is still much to understand, particularly regarding the interactions between scaffolds and their host environment, how these interactions regulate regeneration and how they may be enhanced for optimal tissue repair. In this review, we discuss the concept of dynamic reciprocity as applied to tissue engineering, i.e. how bi-directional signaling between implanted scaffolds and host tissues such as the bladder drives the process of constructive remodeling to ensure successful graft integration and tissue repair. The impact of scaffold content and configuration, the contribution of endogenous and exogenous bioactive factors, the influence of the host immune response and the functional interaction with mechanical stimulation are all considered. In addition, the temporal relationships of host tissue ingrowth, bioactive factor mobilization, scaffold degradation and immune cell infiltration, as well as the reciprocal signaling between discrete cell types and scaffolds are discussed. Improved understanding of these aspects of tissue repair will identify opportunities for optimization of repair that could be exploited to enhance regenerative medicine strategies for urology in future studies.

Mesenchymal stromal cells for sphincter regeneration

Stress urinary incontinence (SUI), defined as the involuntary loss of considerable amounts of urine during increased abdominal pressure (exertion, effort, sneezing, coughing, etc.), is a severe problem to the individuals affected and a significant medical, social and economic challenge. SUI is associated with pelvic floor debility, absence of detrusor contraction, or a loss of control over the sphincter muscle apparatus. The pathology includes an increasing loss of muscle cells, replacement of muscular tissue with fibrous tissue, and general aging associated processes of the sphincter complex. When current therapies fail to cure or improve SUI, application of regeneration-competent cells may be an alternative therapeutic option. Here we discuss different aspects of the biology of mesenchymal stromal cells, which are relevant to their clinical applications and for regenerating the sphincter complex. However, there are reports in favor of and against cell-based therapies. We therefore summarize the potential and the risks of cell-based therapies for the treatment of SUI.

Stress urinary incontinence animal models as a tool to study cell-based regenerative therapies targeting the urethral sphincter

Urinary incontinence (UI) is a major health problem causing a significant social and economic impact affecting more than 200million people (women and men) worldwide. Over the past few years researchers have been investigating cell therapy as a promising approach for the treatment of stress urinary incontinence (SUI) since such an approach may improve the function of a weakened sphincter. Currently, a diverse collection of SUI animal models is available. We describe the features of the different models of SUI/urethral dysfunction and the pros and cons of these animal models in regard to cell therapy applications. We also discuss different cell therapy approaches and cell types tested in preclinical animal models. Finally, we propose new research approaches and perspectives to ensure the use of cellular therapy becomes a real treatment option for SUI.

In vivo imaging of adipose-derived mesenchymal stem cells in female nude mice after simulated childbirth injury

The aim of the present study was to track in vivo the distribution and survival of adipose-derived mesenchymal stem cells (ASCs) transplanted into female BALB/c nude mice following simulated childbirth injury, using green fluorescent protein and luciferase dual labeling, bioluminescent imaging (BLI) and histological evaluation. The results demonstrated that the dually labeled ASCs could be detected for up to eight weeks in vivo. The number of implanted cells decreased during the first three weeks, and then stabilized until the end of the experiment. According to the linear regression plot, ~27,621 implanted cells survived until eight weeks after implantation. Transplanted ASCs predominantly existed at the inoculation site of the vagina, with little or no spread to other organs. Histological analysis confirmed the survival of the engrafted ASCs. The study provided basic evidence that BLI techniques can be used to monitor ASCs in vivo in real time and in the long term. Through local administration, ASCs could survive in the long term to facilitate repair following pelvic-floor injury.

Stress urinary incontinence in women and cell therapy: What can we expect from the future?

Stress urinary incontinence (SUI) is a common disorder that affects a large number of women and their quality of life. The aim of SUI therapy is to restore the existing urethral function via physical therapy, biofeedback, pelvic floor rehabilitation, pharmacological therapy, bulking agents and surgical approaches. Currently, the gold standard for the management of SUI is the tension-free vaginal sling, which provides structural support to the female urethra. However, even minimally invasive surgical procedure such as “slings” carries risks for the patients, lost efficacy over the time and has long-term complications. For this reason, new therapeutic modalities are needed. Cell therapy has been emerged as an alternative to be used on the treatment of different diseases. The use of stem cells as a therapeutic option for SUI is an attractive alternative because, theoretically, injected cells could restore functional muscle cells and aid in sphincter closure in women with sphincter-associated incontinence. This study aims to review the current literature regarding evidences for using stem cell therapy on stress urinary incontinence in women.

Towards a Treatment of Stress Urinary Incontinence: Application of Mesenchymal Stromal Cells for Regeneration of the Sphincter Muscle

Stress urinary incontinence is a significant social, medical, and economic problem. It is caused, at least in part, by degeneration of the sphincter muscle controlling the tightness of the urinary bladder. This muscular degeneration is characterized by a loss of muscle cells and a surplus of a fibrous connective tissue. In Western countries approximately 15% of all females and 10% of males are affected. The incidence is significantly higher among senior citizens, and more than 25% of the elderly suffer from incontinence. When other therapies, such as physical exercise, pharmacological intervention, or electrophysiological stimulation of the sphincter fail to improve the patient’s conditions, a cell-based therapy may improve the function of the sphincter muscle. Here, we briefly summarize current knowledge on stem cells suitable for therapy of urinary incontinence: mesenchymal stromal cells, urine-derived stem cells, and muscle-derived satellite cells. In addition, we report on ways to improve techniques for surgical navigation, injection of cells in the sphincter muscle, sensors for evaluation of post-treatment therapeutic outcome, and perspectives derived from recent pre-clinical studies.

[Stem cell therapy and tissue engineering in regenerative urology]

BACKGROUND

So far there is no clinically established, effective tissue engineering therapy for dysfunction or defects of the lower urinary tract. The concentration of experimental data, initial clinical studies and individual case reports underlines that stem cell treatment for bladder storage and voiding problems, erectile dysfunction and other urothelial defects of the lower urinary tract could close the gap between individualized therapy and potential biomedical applications.

RESULTS

As a result of fundamental research work over the last decade a characterization of various stem cell populations and evaluation of different urological therapy options could be performed. Thereby, aspects of optimal administration, migration, secretion of bioactive factors and stage of differentiation of stem cells with respect to an improved efficiency of treatment were investigated. Because successful tissue regeneration depends on angiogenesis and innervation, particular attention was paid to these important factors.

CONCLUSIONS

Various clinical indications for stem cell treatment and tissue reconstruction that may be required after radical prostatectomy, such as stress urinary incontinence, urethral reconstruction and erectile dysfunction have materialized and are currently being verified in preclinical studies and phase I trials.

Treatment of experimental esophagogastric myotomy with bone marrow mesenchymal stem cells in a rat model

BACKGROUND

Over the last 15 years, many studies demonstrated the myogenic regenerative potential of bone marrow mesenchymal stem cells (BM-MSC), making them an attractive tool for the regeneration of damaged tissues. In this study, we have developed an animal model of esophagogastric myotomy (MY) aimed at determining the role of autologous MSC in the regeneration of the lower esophageal sphincter (LES) after surgery.

METHODS

Syngeneic BM-MSC were locally injected at the site of MY. Histological and functional analysis were performed to evaluate muscle regeneration, contractive capacity, and the presence of green fluorescent protein-positive BM-MSC (BM-MSC-GFP(+) ) in the damaged area at different time points from implantation.

KEY RESULTS

Treatment with syngeneic BM-MSC improved muscle regeneration and increased contractile function of damaged LES. Transplanted BM-MSC-GFP(+) remained on site up to 30 days post injection. Immunohistochemical analysis demonstrated that MSC maintain their phenotype and no differentiation toward smooth or striated muscle was shown at any time point.

CONCLUSIONS & INFERENCES

Our data support the use of autologous BM-MSC to both improve sphincter regeneration of LES and to control the gastro-esophageal reflux after MY.

Stem cell therapy for stress urinary incontinence: a systematic review in human subjects

PURPOSE

To systematically evaluate the current evidence on the safety and efficacy of stem cell therapy (SCT) in stress urinary incontinence (SUI) to allow objective comparison with existing surgical techniques.

METHODS

Systematic literature search of Medline from years 1946-2012 using terms: "stem", "cell", "stress", "urinary", and "incontinence". Included studies presented empirical data on the treatment of SUI using SCT.

OUTCOMES

adverse events, incontinence, quality of life, urodynamic, transurethral ultrasound and urethral EMG findings.

RESULTS

Eight studies met inclusion criteria (seven observational and one randomized). Quality score: median 10.75 of 20 (range 2-12.5). Adverse events: one patient had bladder perforation and two procedures could not be completed due to pain. Temporary urinary retention and cystitis were also reported. Incontinence score: Four studies describe significant improvement. Quality of life: significant improvement in four studies. Urodynamic outcomes: four studies show significant improvement in contractility of urethral sphincter; three studies demonstrate no change in bladder capacity and significant reduction in residual volume; significant improvement in urinary flow three studies, although two found no difference; increase in leak point pressure and detrusor pressure in three studies. Urethral ultrasound: three studies found significant increases in rhabdosphincter thickness and contractility. Urethral EMG: two studies found significant increases in the EMG at rest and at contraction.

CONCLUSION

Data suggest that SC treatment for SUI is safe and effective in the short term. However, the quality and maturity of the data are limited. Robust data from better quality studies comparing this to current surgical techniques are needed.

The effect of endoscopic administration of autologous porcine muscle-derived cells into the urethral sphincter

OBJECTIVE

To verify the fate of autologous porcine myogenic cells after endoscopic administration into the urethral sphincter.

METHODS

This study was performed on pig animal models. The muscle-derived cells (MDCs) were isolated and identified. After the third passage, the 6 × 10(7) of PKH26 labeled cells were injected into the urethral sphincter using a urethrocystoscope. The urethras were collected after 28 days. To analyze the fate of injected cells, the PKH26 presence, the desmin expression, and the distribution of acetylcholine receptors were evaluated in the tissue sections. Moreover, the maximal urethral closure pressure (MUCP) was assessed in experimental and control groups at day 1 and day 28.

RESULTS

The isolated porcine MDCs expressed desmin and were able to differentiate into myotubes in vitro. At day 28 after the transplantation, the depots of PKH26-positive cells were observed in the muscular layer, but also in the submucosa. The staining for desmin revealed that cells located in the muscle layer were integrated with muscle fibers that possessed acetylcholine receptors. However, cells administered into nonmuscle tissue did not express desmin. Urethral pressure profilometry demonstrated no significant differences between MUCP in the transplanted group in comparison to the control group at day 28.

CONCLUSION

The present study demonstrates the successful endoscopic transplantation of myogenic cells into the urethral sphincter. The experiments indicated the key importance of precise cell administration in terms of their fate after the injection.

Regenerative medicine as a new therapeutic strategy for lower urinary tract dysfunction

The use of regenerative medicine for the treatment of organic and functional disorders intractable to conventional treatment has increased worldwide. This innovative medical field might particularly hold promise for the treatment of life-threatening diseases or healing of irreplaceable organs, such as the heart, liver and brain. Dysfunction of the urogenital tract and associated organs other than the kidney might not have immediate life-threatening implications; furthermore, the effectiveness of alternative therapy, such as enterocystoplasty for bladder cancer, has been shown. Therefore, most physicians or scientists do not give much importance to these disorders. However, urological disease has increased in developed societies in recent years. Furthermore, medical costs have also escalated. Disorders of the lower urinary tract, such as urinary disturbance or incontinence, can lead to other complications, impairing quality of life and ultimately increasing short- and long-term medical expenses. Regenerative medicine might hold potential solutions to these problems. Recent advances in urogenital regenerative medicine are reviewed in the present article, with particular reference to lower urinary tract reconstruction. The potential of regenerative medicine for the treatment of intractable lower urinary tract dysfunction compared with conventional treatment is also discussed.

Periurethral skeletal myofibre implantation in patients with urinary incontinence and intrinsic sphincter deficiency: a phase I clinical trial

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Cell therapy using muscle precursor cell (MPC) injections has shown promise for urinary incontinence due to intrinsic sphincter deficiency (ISD), but the cell-preparation process is complex and costly. Implantation of freshly isolated myofibres carrying MPCs, mainly satellite cells, was very efficient in repairing muscle damage in recent animal experiments. In a phase I clinical trial, we investigated whether periurethral myofibre implantation generated local myogenesis and improved continence in 10 patients (five men and five women) with ISD. We found that myofibre implantation increased intraurethral pressure and periurethral electromyographic activity in patients with ISD. There were no serious side-effects.

OBJECTIVES

To assess the safety of periurethral myofibre implantation in patients with urinary incontinence due to intrinsic sphincter deficiency (ISD) To assess the resulting myogenic process and effects on urinary continence.

PATIENTS AND METHODS

An open-label non-randomised phase I clinical trial was conducted in five men and five women with ISD (mean age, 62.5 years). A free muscle strip from the patient's gracilis muscle was implanted around the urethra as a means to deliver locally myofibres and muscle precursor cells (MPCs). Patients were assessed for collection formation and incomplete bladder emptying. The maximum urethral closure pressure (MUCP) and concomitant periurethral electromyographic (EMG) activity were recorded before surgery and 1 and 3 months after surgery. Continence was assessed using the 24-h pad test and self-completed questionnaires, for 12 months.

RESULTS

There were no serious side-effects. Continence improved significantly during the 12-month follow-up in four of the five women, including two who recovered normal continence. In the women, MUCP increased two-fold and de novo EMG periurethral activity was recorded. In the men, MUCP and EMG recordings showed similar improvements but the effect on continence was moderate. The few patients enrolled could affect these results.

CONCLUSIONS

This is the first report of a one-step procedure for transferring autologous MPCs via myofibre implantation in patients with ISD. EMG and urodynamic assessments showed improvement of periurethral muscle activity. Further work is needed to confirm and improve the therapeutic efficiency of this procedure.

Development of stem cell therapy for stress urinary incontinence

PURPOSE OF REVIEW

In recent years, stem cell therapy has been investigated as a promising approach for the treatment of stress urinary incontinence (SUI). This article reviews the biology of stem cells and their applications as a cell-based treatment for SUI. The current status and future direction of this forefront research in urinary incontinence are also examined.

RECENT FINDINGS

During the past decade, adult stem cells have been studied as a potential cell-based approach for the treatment of SUI. The results of current preclinical and clinical studies are presented. These studies demonstrated the improvement in histologic and functional outcomes with stem cell therapies for SUI. Adult stem cells may augment sphincter regeneration and also release trophic factors, promoting vessel and nerve integration into the generated tissues. So far, the findings of the clinical trials are less impressive than the results obtained with animal studies.

SUMMARY

Although stem cell therapy holds much promise for SUI, the clinical applications in patients have been slow to materialize. This challenge, together with the currently limited data on basic science studies and clinical trials, will undoubtedly stimulate new investigations in the near future.

Myogenic potential of whole bone marrow mesenchymal stem cells in vitro and in vivo for usage in urinary incontinence

Urinary incontinence, defined as the complaint of any involuntary loss of urine, is a pathological condition, which affects 30% females and 15% males over 60, often following a progressive decrease of rhabdosphincter cells due to increasing age or secondary to damage to the pelvic floor musculature, connective tissue and/or nerves. Recently, stem cell therapy has been proposed as a source for cell replacement and for trophic support to the sphincter. To develop new therapeutic strategies for urinary incontinence, we studied the interaction between mesenchymal stem cells (MSCs) and muscle cells in vitro; thereafter, aiming at a clinical usage, we analyzed the supporting role of MSCs for muscle cells in vitro and in in vivo xenotransplantation. MSCs can express markers of the myogenic cell lineages and give rise, under specific cell culture conditions, to myotube-like structures. Nevertheless, we failed to obtain mixed myotubes both in vitro and in vivo. For in vivo transplantation, we tested a new protocol to collect human MSCs from whole bone marrow, to get larger numbers of cells. MSCs, when transplanted into the pelvic muscles close to the external urethral sphincter, survived for a long time in absence of immunosuppression, and migrated into the muscle among fibers, and towards neuromuscular endplates. Moreover, they showed low levels of cycling cells, and did not infiltrate blood vessels. We never observed formation of cell masses suggestive of tumorigenesis. Those which remained close to the injection site showed an immature phenotype, whereas those in the muscle had more elongated morphologies. Therefore, MSCs are safe and can be easily transplanted without risk of side effects in the pelvic muscles. Further studies are needed to elucidate their integration into muscle fibers, and to promote their muscular transdifferentiation either before or after transplantation.

Urine is a highly cytotoxic agent: does it influence stem cell therapies in urology?

The state of art of stem cell therapies in urologic regenerative medicine is still under development. There are still many issues before advances in tissue engineering can be introduced for clinical application. The essential question is whether stem cells should be seeded on the urinary tract lumen side. The present experiment, using Real-Time Cell Analyzer (RTCA) DP (Dual Plate) of the xCellligence system (Roche Applied Science, Mannheim, Germany), allowed us to monitor cellular events in real time. In this study we examined the influence of urine on bone marrow-derived mesenchymal stem cells (MSC). Cells were exposed to medium mixed with urine (1:1), medium mix with PBS (Phosphate Buffered Saline) (1:1), only urine, and whole medium without cells as background. The cell number was significantly lower in all groups exposed on medium mixed with urine and urine alone. The results showed that urine is a highly cytotoxic agent whose role in urologic regenerative medicine is underestimated.

Stem cells in gynecology

Stem cell based therapies hold promise for the obstetrician and gynecologist. This article reviews the history of stem cells and some of their current applications in gynecology. Currently, mesenchymal and muscle-derived stem cells are being explored for the treatment of urinary and anal incontinence. Potential stem cell treatments include fistula repair, vaginal tissue engineering, and graft material enhancement. Published animal and human pilot studies demonstrate improved histologic and functional outcomes in those receiving stem cells. Transplanted cells may improve function by local engraftment, trophic factors, or modulation of inflammation. Further clinical and safety studies are needed before clinical application.

Stem cell therapy for voiding and erectile dysfunction

Voiding dysfunction comprises a variety of disorders, including stress urinary incontinence and overactive bladder, and affects millions of men and women worldwide. Erectile dysfunction (ED) also decreases quality of life for millions of men, as well as for their partners. Advanced age and diabetes are common comorbidities that can exacerbate and negatively impact upon the development of these disorders. Therapies that target the pathophysiology of these conditions to halt progression are not currently available. However, stem cell therapy could fill this therapeutic void. Stem cells can reduce inflammation, prevent fibrosis, promote angiogenesis, recruit endogenous progenitor cells, and differentiate to replace damaged cells. Adult multipotent stem cell therapy, in particular, has shown promise in case reports and preclinical animal studies. Stem cells also have a role in urological tissue engineering for ex vivo construction of bladder wall and urethral tissue (using a patient's own cells) prior to transplantation. More recent studies have focused on bioactive factor secretion and homing of stem cells. In the future, clinicians are likely to utilize allogeneic stem cell sources, intravenous systemic delivery, and ex vivo cell enhancement to treat voiding dysfunction and ED.

Neurophysiology and therapeutic receptor targets for stress urinary incontinence

Stress urinary incontinence is the most common type of urinary incontinence in women. Stress urinary incontinence involves involuntary leakage of urine in response to abdominal pressure caused by activities, such as sneezing and coughing. The condition affects millions of women worldwide, causing physical discomfort as well as social distress and even social isolation. This type of incontinence is often seen in women after middle age and it can be caused by impaired closure mechanisms of the urethra as a result of a weak pelvic floor or poorly supported urethral sphincter (urethral hypermobility) and/or a damaged urethral sphincter system (intrinsic sphincter deficiency). Until recently, stress urinary incontinence has been approached by clinicians as a purely anatomic problem as a result of urethral hypermobility requiring behavioral or surgical therapy. However, intrinsic sphincter deficiency has been reported to be more significantly associated with stress urinary incontinence than urethral hypermobility. Extensive basic and clinical research has enhanced our understanding of the complex neural circuitry regulating normal function of the lower urinary tract, as well as the pathophysiological mechanisms that might underlie the development of stress urinary incontinence and lead to the development of potential novel strategies for pharmacotherapy of stress urinary incontinence. Therapeutic targets include adrenergic and serotonergic receptors in the spinal cord, and adrenergic receptors at the urethral sphincter, which can enhance urethral reflex activity during stress conditions and increase baseline urethral pressure, respectively. This article therefore reviews the recent advances in stress urinary incontinence research and discusses the neurophysiology of urethral continence reflexes, the etiology of stress urinary incontinence and potential targets for pharmacotherapy of stress urinary incontinence.

Autologous Bone Marrow-Derived Cells Regenerate Urethral Sphincters

Regenerative medicine based on tissue engineering and/or stem cell therapy techniques has the potential to improve irreversibly damaged tissues. Surgical injury to the lower urinary tract can occur as a result of radical prostatectomy or bladder neck surgery. Regeneration of urethral sphincters could be an effective treatment for post-surgical intrinsic sphincter deficiency (ISD)-related urinary incontinence. The replacement, enhancement, and/or recovery the urethral sphincter striated and smooth muscles could increase urethral closure pressure to help patients regain continence. Stem cells from muscle-derived satellite or adipose-derived mesenchymal cells provide temporary improvement in urethral closure pressure but do not reconstruct the muscle layer structures. Our strategy to accomplish regeneration of urethral sphincters is the utilization of autologous bone marrow-derived cells. We have developed a freeze injury model of ISD in rabbits. Freezing of the urinary sphincter causes loss of the majority of striated and smooth muscle cells, and causes a significant decrease in leak point pressure. In this review, we show that the autologous bone marrow-derived cells implanted within the freeze-injured sphincters differentiate into striated or smooth muscle cells. These cells then develop to reconstitute muscle layer structures within the sphincter. Furthermore, the leak point pressure of cell-implanted rabbits is significantly higher than that of cell-free injected controls. We conclude that implantation of autologous bone marrow-derived cells could be an effective treatment for human post-surgical ISD-related urinary incontinence.

Stem cell therapy for stress urinary incontinence: a critical review

Stress urinary incontinence (SUI) is a prevailing health problem that severely impacts quality of life. Because SUI is mainly due to urethral sphincter deficiency, several preclinical and clinical trials have investigated whether transplantation of patient's own skeletal muscle-derived cells (SkMDCs) can restore the sphincter musculature. The specific cell type of SkMDCs has been described as myoblasts, satellite cells, muscle progenitor cells, or muscle-derived stem cells, and thus may vary from study to study. In more recent years, other stem cell (SC) types have also been tested, including those from the bone marrow, umbilical cord blood, and adipose tissue. These studies were mostly preclinical and utilized rat SUI models that were established predominantly by pudendal or sciatic nerve injury. Less frequently used animal models were sphincter injury and vaginal distension. While transurethral injection of SCs was employed almost exclusively in clinical trials, periurethral injection was used in all preclinical trials. Intravenous injection was also used in one preclinical study. Functional assessment of therapeutic efficacy in preclinical studies has relied almost exclusively on leak point pressure measurement. Histological assessment examined the sphincter muscle content, existence of transplanted SCs, and possible differentiation of these SCs. While all of these studies reported favorable functional and histological outcomes, there are questions about the validity of the animal model and claims of multilineage differentiation. In any event, SC transplantation appears to be a promising treatment for SUI.

Models for sensory neurons of dorsal root ganglia and stress urinary incontinence

AIMS

To discuss (1) animal models for investigating bladder afferent pathways from the spinal cord to the brain and (2) animal models of stress urinary incontinence (SUI) with a special emphasis on functional and histopathological characteristics of each model.

METHODS

Literature review of spinal mechanisms of bladder afferent pathways and animal models of SUI.

RESULTS

Electrophysiological studies in the rat using pelvic nerve stimulation and recording of evoked potentials in the periaqueductal gray (PAG) prove to be a valuable tool to examine spinal mechanisms of bladder afferent pathways. Animal models of SUI in the rat include vaginal distention as simulated birth trauma, pudendal nerve crush or transection, urethral sphincter injury by electrocauterization, transabdominal urethrolysis, periurethral botulinum-A toxin injection, and pubo-urethral ligament transection. Functional and histopathological changes in the continence mechanism after injury are different between models.

CONCLUSIONS

Using animal models for sensory neurons, intrathecal and intravenous administration of certain drugs can be tested whether they affect the bladder afferent pathways from the spinal cord to the PAG. Animal models of SUI can serve as a tool to develop new pharmacologic therapies or periurethral injection therapies using stem cell implants.

Stem cell therapy for incontinence: where are we now? What is the realistic potential?

A significant number of women experience stress urinary incontinence (SUI), which greatly affects their quality of life. Recent research investigating utilization of stem cells and their derivatives for the prevention and treatment of SUI has been performed to test the effect of cell source and method of administration in several animal models of SUI. The type of stem cell, timing of optimal dose or doses after injury, mechanism of action of stem cells, and route of administration must be investigated both preclinically and clinically before stem cell therapy becomes a possible treatment for SUI, although the future of this therapy looks promising. This article reviews the progress in stem cell research for incontinence and describes areas of future work as suggested by research in other fields.