Periurethral cellular injection: comparison of muscle-derived progenitor cells and fibroblasts with regard to efficacy and tissue contractility in an animal model of stress urinary incontinence

Male stress urinary incontinence: a review of surgical treatment options and outcomes

Introduction and Objective. Iatrogenic male stress urinary incontinence (SUI) affects a percentage of men undergoing urologic procedures with a significant impact on quality of life. The treatment of male SUI has evolved significantly with multiple current options for treatment available. The current paper discusses preoperative evaluation of male SUI, available surgical options with reported outcomes, and postoperative complication management. Methods. A pubMed review of available literature was performed and summarized on articles reporting outcomes of placement of the artificial urinary sphincter (AUS) or male slings including the bone anchored sling (BAS), retrourethral transobturator sling (RTS), adjustable retropubic sling (ARS), and quadratic sling. Results. Reported rates of success (variably defined) for BAS, RTS, ARS, and AUS are 36-67%, 9-79%, 13-100%, and 59-91% respectively. Complications reported include infection, erosion, retention, explantation, and transient pain. Male slings are more commonly performed in cases of low-to-moderate SUI with decreasing success with higher degrees of preoperative incontinence. Conclusions. An increasing number of options continue to be developed for the management of male SUI. While the AUS remains the gold-standard therapy for SUI, male sling placement is a proven viable alternative therapy for low-to-moderate SUI.

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.

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.

Safety, efficacy and health related quality of life of autologous myoblast transplantation for treatment of urinary incontinence in children with bladder exstrophy-epispadias complex

PURPOSE

Children with bladder exstrophy-epispadias complex undergoing endourethral autologous myoblast transplantation to treat urinary incontinence were evaluated at 4 years of followup regarding the safety, efficacy and durability of the procedure, and health related quality of life.

MATERIALS AND METHODS

Seven boys underwent autologous myoblast transplantation between May and December 2006. All patients had persistent urinary incontinence after bladder neck reconstruction and bulking agent injection. Patients were followed for 4 years after autologous myoblast transplantation regarding clinical outcomes and cystometric, urodynamic, uroflowmetric and urethrocystoscopic evaluations. Health related quality of life was also measured before treatment and at final followup.

RESULTS

No evidence of urinary obstruction was observed. Five children (71%) were completely continent and 2 (29%) were socially dry with complete daytime dryness at final followup. Health related quality of life was improved significantly. Urodynamic studies revealed a progressive increase in bladder capacity (p <0.001). Mean detrusor leak point pressure showed a 27 cm H(2)O (158%) increase during 4-year followup. Uroflowmetry parameters of voided volume and average maximum flow rate were improved significantly (p <0.001).

CONCLUSIONS

The 4-year outcomes demonstrate that autologous myoblast transplantation for urinary incontinence in children with bladder exstrophy-epispadias complex is relatively reliable, reproducible, safe and effective with minimal morbidity. This novel treatment represents a promising therapeutic approach in patients with urinary incontinence. Further randomized trials with larger numbers of patients and longer followup are needed.

Inhibition of fibroblast differentiation of muscle-derived stem cells in cell implantation treatment of stress urinary incontinence

The aim of this study was to investigate the effects of transforming growth factor-β1 (TGF-β1) stimulation and the blocking of the TGF-β1/Smad3 signaling pathway by vector-mediated Smad3 shRNA on muscle-derived stem cells (MDSCs) in cell implantation treatment of stress urinary incontinence (SUI) of the rat. MDSCs were infected with the GC-shSmad3 lentivirus vector. Five days after infection, the cells were treated with TGF-β1. The expression levels of desmin (a marker of muscle differentiation) and vimentin (a marker of fibroblast differentiation) were tested by real-time PCR and Western blot. GC-shSmad3 lentivirus-infected MDSCs were injected into the bladder neck and proximal urethra of SUI rats. Urodynamic test was used to measure leak point pressure (LPP) at 2 weeks and 4 weeks after MDSC transplantation. Upregulated expression of vimentin and downregulated expression of desmin were found in MDSCs after culture with TGF-β1 in vitro. GC-shSmad3 lentivirus infection inhibited fibroblast differentiation of MDSCs but allowed muscle differentiation with desmin expression. In vivo experiments showed that GC-shSmad3 lentivirus infection could improve MDSC-mediated repairing of urethra sphincter function. In conclusion, blocking Smad3 expression inhibits the fibroblast differentiation of MDSCs induced by TGF-β1 in vitro and improves the repairing of urethral sphincter function by inhibiting the fibroblast differentiation of MDSCs in a rat model of SUI in vivo.

The clinical relevance of cell-based therapy for the treatment of stress urinary incontinence

Stress urinary incontinence is a common disorder affecting the quality of life for millions of women worldwide. Effective surgical procedures involving synthetic permanent meshes exist, but significant short- and long-term complications occur. Cell-based therapy using autologous stem cells or progenitor cells presents an alternative approach, which aims at repairing the anatomical components of the urethral continence mechanism. In vitro expanded progenitor cells isolated from muscle biopsies have been most intensely investigated, and both preclinical trials and a few clinical trials have provided proof of concept for the idea. An initial enthusiasm caused by positive results from early clinical trials has been dampened by the recognition of scientific irregularities. At the same time, the safety issue for cell-based therapy has been highlighted by the appearance of new and comprehensive regulatory demands. The influence on the cost effectiveness, the clinical relevance and the future perspectives of the present clinical approach are discussed.

Slow-adhering stem cells derived from injured skeletal muscle have improved regenerative capacity

A wide variety of myogenic cell sources have been used for repair of injured and diseased muscle including muscle stem cells, which can be isolated from skeletal muscle as a group of slow-adhering cells on a collagen-coated surface. The therapeutic use of muscle stem cells for improving muscle regeneration is promising; however, the effect of injury on their characteristics and engraftment potential has yet to be described. In the present study, slow-adhering stem cells (SASCs) from both laceration-injured and control noninjured skeletal muscles in mice were isolated and studied. Migration and proliferation rates, multidifferentiation potentials, and differences in gene expression in both groups of cells were compared in vitro. Results demonstrated that a larger population of SASCs could be isolated from injured muscle than from control noninjured muscle. In addition, SASCs derived from injured muscle demonstrated improved migration, a higher rate of proliferation and multidifferentiation, and increased expression of Notch1, STAT3, Msx1, and MMP2. Moreover, when transplanted into dystrophic muscle in MDX/SCID mice, SASCs from injured muscle generated greater engraftments with a higher capillary density than did SASCs from control noninjured muscle. These data suggest that traumatic injury may modify stem cell characteristics through trophic factors and improve the transplantation potential of SASCs in alleviating skeletal muscle injuries and diseases.

Swimming: effects on stress urinary incontinence and the expression of nerve growth factor in rats following transabdominal urethrolysis

PURPOSE

Stress urinary incontinence (SUI) commonly occurs in women, and it has an enormous impact on quality of life. Surgery, drugs, and exercise have been recommended for the treatment of this disease. Among these, exercise is known to be effective for the relief of symptoms of SUI; however, the efficacy and underlying mechanisms of the effect of exercise on SUI are poorly understood. We investigated the effect of swimming the symptom of SUI in relation to the expression of nerve growth factor (NGF) in rats.

METHODS

Transabdominal urethrolysis was used to induce SUI, in Sprague-Dawley rats. The experimental groups were divided into the following three groups: sham-operation group, transabdominal urethrolysis-induced group, and transabdominal urethrolysis-induced and swimming group. The rats in the swimming group were forced to swim for 30 minutes once daily starting 2 weeks after SUI induction and continuing for 4 weeks. For this study, determination of abdominal leak point pressure and immunohistochemistry for NGF in the urethra and in the neuronal voiding centers (medial preoptic nucleus [MPA], ventrolateral periaqueductal gray [vlPAG], pontine micturition center [PMC], and spinal cord [L4-L5]) were performed.

RESULTS

Transabdominal urethrolysis significantly reduced the abdominal leak point pressure, thereby contributing to the induction of SUI. Abdominal leak point pressure, however, was significantly improved by swimming. The expression of NGF in the urethra and in the neuronal voiding centers (MPA, vlPAG, PMC, and L4-L5) relating to micturition was enhanced by the induction of SUI. Swimming, however, significantly suppressed SUI-induced NGF expression.

CONCLUSIONS

Swimming alleviated symptoms of transabdominal urethrolysis-induced SUI, as assessed by an increase in abdominal leak point pressure. The underlying mechanisms of these effects of swimming might be ascribed to the inhibitory effect of swimming on NGF expression.

Development of cellular therapy for the treatment of stress urinary incontinence

Stress urinary incontinence (SUI) is highly prevalent and associated with a reduced quality of life. An intact rhabdosphincter at the mid-urethra is mandatory to maintain urinary continence. Adult stem cell injection therapy for the regenerative repair of an impaired sphincter is currently at the forefront of incontinence research. The implanted cells will fuse with muscle and release trophic factors promoting nerve and muscle integration. Hereby, we review the use of mesenchymal stem cell therapy for SUI and the experience with the development of muscle-derived stem cells.

Urethral compensatory mechanisms to maintain urinary continence after pudendal nerve injury in female rats

INTRODUCTION AND HYPOTHESIS

This study was conducted to investigate the urethral compensatory mechanisms to maintain urinary continence after pudendal nerve injury.

METHODS

In naive, acute pudendal nerve transection (PNT) and 4 weeks after PNT (PNT-4w) female rats, leak point pressures (LPPs) during bladder compression were measured before and after the application of hexamethonium (C6), propranolol, and N (ω)-nitro-L: -arginine-methyl ester (L: -NAME), or terazosin and atropine. Responses to carbachol and phenylephrine of proximal and middle urethral muscle strips from naive and PNT-4w rats were also examined.

RESULTS

LPPs were significantly decreased in PNT rats but not in PNT-4w rats. LPPs in PNT rats were significantly increased by C6 or L-NAME while LPPs in PNT-4w rats were significantly decreased by C6, or terazosin and atropine. Excitatory responses to carbachol and phenylephrine in the proximal urethral muscle were significantly larger in PNT-4w rats.

CONCLUSIONS

These results suggest that α(1)-adrenoceptor and muscarinic receptor-mediated contractility is upregulated in the proximal urethra 4 weeks after PNT.

Stem cells for the treatment of urinary incontinence

Stress urinary incontinence (SUI) is highly prevalent. As of now, there is no minimally invasive long-term treatment available. Adult stem cells are nonimmunogenic and have the ability to self-renew and to differentiate into multiple cell types. Over the past decade, in vivo studies have described periurethral injections of adult-derived stem cells for the treatment of SUI. The ultimate goal has been to achieve a permanent cure for SUI by restoration of the intrinsic and extrinsic urethral sphincter and the surrounding connective tissue, including peripheral nerves and blood vessels. For this purpose, future studies need to focus on delivery systems, cell survival, and functional improvement of the urethral closure mechanism, including improvement of innervation and vascularization.

Animal models of stress urinary incontinence

Stress urinary incontinence (SUI) is a common health problem significantly affecting the quality of life of women worldwide. Animal models that simulate SUI enable the assessment of the mechanism of risk factors for SUI in a controlled fashion, including childbirth injuries, and enable preclinical testing of new treatments and therapies for SUI. Animal models that simulate childbirth are presently being utilized to determine the mechanisms of the maternal injuries of childbirth that lead to SUI with the goal of developing prophylactic treatments. Methods of assessing SUI in animals that mimic diagnostic methods used clinically have been developed to evaluate the animal models. Use of these animal models to test innovative treatment strategies has the potential to improve clinical management of SUI. This chapter provides a review of the available animal models of SUI, as well as a review of the methods of assessing SUI in animal models, and potential treatments that have been tested on these models.

Effect of Treadmill Exercise on Leak-point pressure and Neuronal Activation in Brain of Rats with Stress Urinary Incontinence

PURPOSE

Stress urinary incontinence (SUI) commonly occurs in women, and it causes enormous impact on quality of life. Surgery, drugs, and exercise have been recommended for the treatment of this disease. Among these exercise is also known to be effective for relieving thesymptoms of SUI, however, the efficacy and underlying mechanisms of exercise on SUI are poorly understood. In the present study, we investigated the effect of treadmill exercise on abdominal leak-point pressure and neuronal activity in the medial preoptic nucleus (MPA), ventrolateral periaqueductal gray (vlPAG), and pontine micturition center (PMC) following urethrolysis in rats.

MATERIALS AND METHODS

Adult female Sprague-Dawley rats, weighing 250±10 g (9 weeks old), were used in this study. After having undergone transabdominal urethrolysis to induce SUI, the rats were divided into three groups (n=6 in each group): a sham operation group, an SUI-induced group, and an SUI-induced and treadmill exercise group. The rats in the exercise group performed treadmill running for 30 min once a day starting 2 weeks after the induction of SUI and continuing for 4 weeks after surgery. For this study, determination of abdominal leak point pressure and immunohistochemistry for c-Fos in the brain were performed.

RESULTS

Induction of transabdominal urethrolysis significantly reduced the abdominal leak point pressure, thereby contributing to the induction of SUI. In contrast, abdominal leak point pressure was significantly improved by treadmill exercise. The expression of c-Fosin the MPA, vlPAG, and PMC, the brain areas relating to micturition, was enhanced by the induction of SUI, whereas treadmill exercise significantly suppressed SUI-induced c-Fos expression, suggesting that neuronal activation in the micturition centers was suppressed by treadmill exercise.

CONCLUSION

The present results suggest that treadmill exercise may be an effective therapeutic modality for ameliorating the symptoms of SUI.

Tissue engineering and stem cells: basic principles and applications in urology

To overcome problems of damaged urinary tract tissues and complications of current procedures, tissue engineering (TE) techniques and stem cell (SC) research have achieved great progress. Although diversity of techniques is used, urologists should know the basics. We carried out a literature review regarding the basic principles and applications of TE and SC technologies in the genitourinary tract. We carried out MEDLINE/PubMed searches for English articles until March 2010 using a combination of the following keywords: bladder, erectile dysfunction, kidney, prostate, Peyronie's disease, stem cells, stress urinary incontinence, testis, tissue engineering, ureter, urethra and urinary tract. Retrieved abstracts were checked, and full versions of relevant articles were obtained. Scientists have achieved great advances in basic science research. This is obvious by the tremendous increase in the number of publications. We divided this review in two topics; the first discusses basic science principles of TE and SC, whereas the second part delineates current clinical applications and advances in urological literature. TE and SC applications represent an alternative resource for treating complicated urological diseases. Despite the paucity of clinical trials, the promising results of animal models and continuous work represents the hope of treating various urological disorders with this technology.

Postpartum stress urinary incontinence: lessons from animal models

Postpartum stress urinary incontinence (SUI) is associated with chronic SUI in later life, which is 240% more likely to occur in women who deliver vaginally than those who did not. The etiology of SUI is multifactoral and has been associated with defects in both neuromuscular and structural components of continence. Specifically, clinical studies have demonstrated that pudendal nerve damage occurs during vaginal delivery, supporting the concept that neuromuscular damage to the continence mechanism can result in postpartum SUI. Urethral hypermobility and the loss of pelvic floor support, such as that involved in pelvic organ prolapse, have also been associated with SUI. Animal models provide an opportunity to investigate these injuries, individually and in combination, enabling researchers to gain further insight into their relative contributions to the development of SUI and the effectiveness of potential therapies for it. This article discusses the use of animal models of postpartum SUI in addition to the broad insights into treatment efficacy they provide.

[Muscle-derived stem cell therapy for stress urinary incontinence]

The knowledge of the urinary effort incontinence (UEI) has increased, giving like result an ample range of different therapeutic options available. The middle urethra and external urethral sphincter are the focus in management of UEI. Stem cells therapy for the regenerative repair of the deficient sphincter has been the leading research of incontinence. Obtaining autologous myoblasts and fibroblasts of skeletal muscle-biopsies, cultivating them and transplanting them after its differentiation, into the external urethral sphincter it warns a new concept in the treatment of the incontinence. Instead of using heterologous materials such as synthetic mesh (slings) or bulking agents (collagen, silicone, etc); we now have the potential to restore function with the use of autologous stem cells.

Extraordinary muscular structure leads to urethral injury after vaginal delivery in animal study

INTRODUCTION AND HYPOTHESIS

The aim of this study is to explore causality of birth trauma after vaginal delivery and anatomical findings.

METHODS

A total of 28 virgin mice were studied. Treatment groups received vaginal distention. Specimens were collected and subjected to the following fluorescence stains: progenitor cell (c-kit), smooth muscle (SMA), fibroblast (vimentin), and skeleton muscle (Masson's trichrome). Confocal microscopy was used to screen all of the urogenital tissue to localize the stained cells.

RESULTS

Fibroblasts were spread all over perivaginal and urethral surroundings. Progenitor cells appeared at urethral-vagina intersection and urethral circle. They were noticeable only within smooth muscle layer. Two extraordinary skeleton muscle bands appeared on the urethra bilaterally.

CONCLUSIONS

Our study demonstrates existence of muscle bands at the bilateral urethra. They can limit the mobility of urethra during vaginal delivery and thereby cause urethra injury. Progenitor cells are located only in the smooth muscle of the urethral circle.

Stress urinary incontinence in women

Stress urinary incontinence (SUI) is a major health issue that affects millions of patients each year. Traditionally, surgical procedures such as slings or bladder neck suspension were the only options to treat this condition. In recent years, multiple minimally invasive options to treat SUI were introduced into the market. These include bulking agents, injection of stem cells into the rhabdosphincter, and adjustable continence therapy devices. These procedures are simple, minimally invasive, and well tolerated by patients. This article reviews the benefits, efficiency, side effects, and complications of these minimally invasive methods for treatment of SUI.

Stem cells for stress urinary incontinence: the adipose promise

Stress urinary incontinence (SUI), the most common type of incontinence in women, is a frequent and costly ailment responsible for an alteration in the quality of life. Although medical treatment gives some rather deceiving results, surgical techniques that include colposuspension or tension-free vaginal tape, employed in cases of urethral support defect, give a 5-year cure rate of more than 80%. However, these techniques could lead to complications or recurrence of symptoms. Recently, the initiation of urethral cell therapy has been undertaken by doctors and researchers. One principal source of autologous adult stem cells is generally used: muscle precursor cells (MPCs) which are the progenitors of skeletal muscle cells. Recently, a few research groups have shown interest in the MPCs and their potential for the treatment of urinary incontinence. However, using MPCs or fibroblasts isolated from a striated muscle biopsy could be questionable on several points. One of them is the in vitro cultivation of cells, which raises issues over the potential cost of the technique. Besides, numerous studies have shown the multipotent or even the pluripotent nature of stromal vascular fraction (SVF) or adipose-derived stem cells (ASCs) from adipose tissue. These cells are capable of acquiring in vitro many different phenotypes. Furthermore, recent animal studies have highlighted the potential interest of SVF cells or ASCs in cell therapy, in particular for mesodermal tissue repair and revascularization. Moreover, the potential interest of SVF cells or ASCs for the treatment of urinary incontinence in women is supported by many other characteristics of these cells that are discussed here. Because access to these cells via lipoaspiration is simple, and because they are found in very large numbers in adipose tissue, their future potential as a stem cell reservoir for use in urethral or other types of cell therapy is enormous.

Multi-potent differentiation of human purified muscle-derived cells: potential for tissue regeneration

OBJECTIVE

To investigate whether CD34+ purified human muscle-derived cells (hMDCs) are capable of multiple lineage differentiation.

MATERIALS AND METHODS

The hMDCs were isolated from human skeletal muscle and purified using a CD34+ cell selection system (Dynal Biotech, Oslo, Norway). Adherent populations of cells were expanded in culture and cell differentiation was induced using different kinds of growth factors and different differentiation-conditional media. The immunohistochemical properties of CD34+ hMDCs were examined after varying periods in culture. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were used to investigate the gene expression of the undifferentiated and differentiated hMDCs.

RESULTS

Using special differentiation conditions the CD34+ hMDCs could be differentiated into myogenic cells, adipocytes, osteocytes and chondrocytes. The differentiation was confirmed by immunohistochemistry. RT-PCR and Western blotting showed multiple-lineage gene-level expression in the different cultivation periods of the differentiated cells.

CONCLUSIONS

We confirmed the multi-lineage capacity of a population of stem cells, termed CD34+ hMDCs. Our findings showed that CD34+ hMDCs are capable of multiple mesodermal-lineage differentiation, as shown by the expression of several lineage-specific genes. They can be differentiated toward the myogenic, osteogenic, adipogenic and chondrogenic lineages. These cells might have potential for use in tissue regeneration.

Isolation of a slowly adhering cell fraction containing stem cells from murine skeletal muscle by the preplate technique

This protocol details a procedure, known as the modified preplate technique, which is currently used in our laboratory to isolate muscle cells on the basis of selective adhesion to collagen-coated tissue culture plates. By employing this technique to murine skeletal muscle, we have been able to isolate a rapidly adhering cell (RAC) fraction within the earlier stages of the process, whereas a slowly adhering cell (SAC) fraction containing muscle-derived stem cells is obtained from the later stages of the process. This protocol outlines the methods and materials needed to isolate RAC and SAC populations from murine skeletal muscle. The procedure involves mechanical and enzymatic digestion of skeletal muscle tissue with collagenase XI, dispase and trypsin followed by plating the resultant muscle slurry on collagen type I-coated flasks where the cells adhere at different rates. The entire preplate technique requires 5 d to obtain the final preplate SAC population. Two to three additional days are usually required before this population is properly established. We also detail additional methodologies designed to further enrich the resultant cell population by continuing the modified preplating process on the SAC population. This process is known as replating and requires further time.

1-year follow-up of autologous muscle-derived stem cell injection pilot study to treat stress urinary incontinence

We hereby report a 1-year follow-up on eight women in the first North America trial in which stress urinary incontinence (SUI) was treated with muscle-derived stem cell injections. Mean and median follow-up in this group was 16.5 and 17 months (range 3-24 months). Improvement in SUI was seen in five of eight women, with one achieving total continence. Onset of improvement was between 3 and 8 months after injection. Cure or improvement continued at a median of 10 months. No serious adverse events were reported.

Muscle derived stem cell therapy for stress urinary incontinence

AIM

The aim of this article is to discuss the potential of muscle-derived stem cells (MDSCs) for rhabdosphincter regeneration and to review the early clinical experiences with its application in patients with stress urinary incontinence.

RESULTS

In anatomical and functional studies of the human and animal urethra, the middle urethral contained rhabdosphincter is critical for maintaining continence. Transplanted stem cells have the ability to undergo self-renewal and multipotent differentiation, leading to sphincter regeneration. In addition, such cells may release, or be engineered to release, neurotrophins with subsequent paracrine recruitment of endogenous host cells to concomitantly promote a regenerative response of nerve-integrated muscle.

CONCLUSION

Cell-based therapies are most often associated with the use of autologous multipotent stem cells, such as bone marrow stromal cells. However, harvesting bone marrow stromal stem cells requires a general anesthetic, can be painful, and has variable yield of stem cells upon processing. In contrast, with appropriate experience, alternative autologous adult stem cells such as muscle-derived stem cells and adipose-derived stem cells can be obtained in large quantities and with minimal discomfort.

Animal models of female stress urinary incontinence

PURPOSE

Urinary incontinence affects 40% of women in the United States and stress urinary incontinence accounts for a large portion of affected patients. As defined by the International Continence Society, stress urinary incontinence is the involuntary leakage of urine upon effort, exertion, sneezing or coughing. Since the ultimate success of long-term management for any condition is based on an understanding of its pathophysiology, and because the pathophysiology of stress urinary incontinence is incompletely defined, animal models have recently been developed to better understand stress urinary incontinence and develop novel treatment alternatives.

MATERIALS AND METHODS

Several animal models for urethral dysfunction have emerged in the last few years, including those based on pathophysiological theories of urethral sphincter dysfunction that were designed to simulate maternal birth trauma. Other models have focused on the creation of a durable model of dysfunction for investigating novel treatments.

RESULTS

Since animals cannot express intent, these animal models have focused on measuring decreased urethral resistance. The most widely used methods are the sneeze test, the tilt table technique and the leak point pressure test. Newer techniques include abdominal leak point pressure, urethral pressure measurement and retrograde urethral perfusion pressure. In addition to the advantages and disadvantages of each technique, all methods measure the composite contribution to urethral resistance from smooth and striated muscle, urethral closure and connective tissue, although none measures intent.

CONCLUSIONS

We critically reviewed the different models of stress urinary incontinence and urethral dysfunction as well as the different methods of measuring urethral resistance.

Physiological effects of human muscle-derived stem cell implantation on urethral smooth muscle function

The physiological effects of human muscle-derived stem cell (MDSC) implantation on urethral smooth muscle function were investigated in pudendal nerve-transected nude rats with human MDSC (TM) or saline (TS) injection into the proximal urethra compared with sham-operated, saline-injected nude rats (SS). Leak point pressure (LPP) before and after hexamethonium application, which can block autonomic efferent nerves, and proximal urethral contractile responses to carbachol and phenylephrine in muscle strip study were examined 6 weeks after the implantation. There was no significant difference between the LPPs in SS and TM. Following hexamethonium application, the LPP in TM was, however, significantly decreased compared with SS. The contractile responses to phenylephrine, but not to carbachol, in TM were significantly increased compared with SS and TS. These results suggest that the restorative effects of MDSCs are mediated by autonomic nerves and that increased sensitivity of alpha(1)-adrenoceptors may be related to restore the deficient urethral function.

Association of overactive bladder and stress urinary incontinence in rats with pudendal nerve ligation injury

Approximately one-third of patients with stress urinary incontinence (SUI) also suffer from urgency incontinence, which is one of the major symptoms of overactive bladder (OAB) syndrome. Pudendal nerve injury has been recognized as a possible cause for both SUI and OAB. Therefore, we investigated the effects of pudendal nerve ligation (PNL) on bladder function and urinary continence in female Sprague-Dawley rats. Conscious cystometry with or without capsaicin pretreatment (125 mg/kg sc), leak point pressures (LPPs), contractile responses of bladder muscle strips to carbachol or phenylephrine, and levels of nerve growth factor (NGF) protein and mRNA in the bladder were compared in sham and PNL rats 4 wk after the injury. Urinary frequency detected by a reduction in intercontraction intervals and voided volume was observed in PNL rats compared with sham rats, but it was not seen in PNL rats with capsaicin pretreatment that desensitizes C-fiber-afferent pathways. LPPs in PNL rats were significantly decreased compared with sham rats. The contractile responses of detrusor muscle strips to phenylephrine, but not to carbachol, were significantly increased in PNL rats. The levels of NGF protein and mRNA in the bladder of PNL rats were significantly increased compared with sham rats. These results suggest that pudendal nerve neuropathy induced by PNL may be one of the potential risk factors for OAB, as well as SUI. Somato-visceral cross sensitization between somatic (pudendal) and visceral (bladder) sensory pathways that increases NGF expression and alpha(1)-adrenoceptor-mediated contractility in the bladder may be involved in this pathophysiological mechanism.

Effect of muscle-derived stem cells on the restoration of corpora cavernosa smooth muscle and erectile function in the aged rat

OBJECTIVE

To determine whether skeletal muscle-derived stem cells (MDSCs) convert into smooth muscle cells (SMCs) both in vitro and in vivo, and in so doing ameliorate the erectile dysfunction (ED) of aged rats, and whether endogenous stem cells are present in the rat corpora cavernosa.

MATERIALS AND METHODS

MDSCs were obtained from mouse muscle, and shown by immunocytochemistry for alpha-smooth muscle actin (alpha SMA) to originate in vitro in myofibroblasts and SMCs, discriminating SMCs by calponin 1 expression. In vivo these MDSCs, labelled with 4',6-diamidino-2-phenylindole, were implanted into the corpora cavernosa of young adult (5-month old) and aged (20-month old) rats for 2 and 4 weeks. Histological changes were assessed by immunohistochemistry and quantitative Western blot. Functional changes were determined by electrical field stimulation (EFS) of the cavernosal nerve.

RESULTS

The exogenous cells replicated and converted into SMCs, as shown in corporal tissue sections by confocal immunofluorescence microscopy for proliferating cell nuclear antigen (PCNA), alpha SMA, and smoothelin, and also by Western blot for alpha SMA and PCNA. MDSC differentiation was confirmed by the activation of the alpha SMA promoter-linked beta-galactosidase in transfected cells, both in vitro and after implantation in the corpora. Putative endogenous stem cells were shown in corporal tissue sections and Western blots by detecting CD34 and a possible Sca1 variant. EFS showed that implanted MDSCs raised in aged rats the maximal intracavernosal pressure/mean arterial pressure levels above (2 weeks) or up to (4 weeks) those of young adult rats.

CONCLUSIONS

MDSCs implanted into the corpora cavernosa of aged rats converted into SMCs and corrected ED, and endogenous cells expressing stem cell markers were also found in untreated tissue. This suggests that exogenous stem cell implantation and/or endogenous stem cell modulation might be viable therapeutic approaches for ageing-related ED.

State of the art of where we are at using stem cells for stress urinary incontinence

AIMS

This review aims to discuss: 1) the neurophysiology, highlighting the importance of the middle urethra, and treatment of stress urinary incontinence (SUI); 2) current injectable cell sources for minimally-invasive treatment; and 3) the potential of muscle-derived stem cells (MDSCs) for the delivery of neurotrophic factors.

METHODS

A PUB-MED search was conducted using combinations of heading terms: urinary incontinence, urethral sphincter, stem cells, muscle, adipose, neurotrophins. In addition, we will update the recent work from our laboratory.

RESULTS

In anatomical and functional studies of human and animal urethra, the middle urethra containing rhabdosphincter, is critical for maintaining continence. Cell-based therapies are most often associated with the use of autologous multipotent stem cells, such as the bone marrow stromal cells. However, harvesting bone marrow stromal stem cells is difficult, painful, and may yield low numbers of stem cells upon processing. In contrast, alternative autologous adult stem cells such as MDSCs and adipose-derived stem cells can be easily obtained in large quantities and with minimal discomfort. Not all cellular therapies are the same, as demonstrated by the differences in safety and efficacy from muscle-sourced MDSCs versus myoblasts versus fibroblasts.

CONCLUSIONS

Transplanted stem cells may have the ability to undergo self-renewal and multipotent differentiation, leading to sphincter regeneration. In addition, such cells may release, or be engineered to release, neurotrophins with subsequent paracrine recruitment of endogenous host cells to concomitantly promote a regenerative response of nerve-integrated muscle. The dawn of a new paradigm in the treatment of SUI may be near.

Sphincter contractility after muscle-derived stem cells autograft into the cryoinjured anal sphincters of rats

PURPOSE

This study was designed to determine whether the injection of muscle-derived stem cells into the anal sphincter can improve functional properties in a fecal incontinence rat model.

METHODS

Cryoinjured rats were utilized as a fecal incontinence model. The gastrocnemius muscles of normal three-week-old female Sprague-Dawley rats were used for the purification of the muscle-derived stem cells. The experimental group was divided into three subgroups: normal control; cryoinjured; and muscle-derived stem cells (3 x 10(6) cells) injection group of cryoinjured rats. All groups were subsequently employed in contractility experiments using muscle strips from the anal sphincter, one week after preparation.

RESULTS

Contractility in the cryoinjured group was significantly lower than in the control after treatment with acetylcholine and KCl. In the muscle-derived stem cells injection group, contraction amplitude was higher than in the cryoinjured group but not significantly (20.5 +/- 21.3 vs. 17.3 +/- 3.4 g per gram tissue, with acetylcholine (10(-4) mol/l); 31 +/- 14.2 vs. 18.4 +/- 7.9 g per gram tissue, with KCl (10(-4) mol/l)). PKH-26-labeled transplanted cells were detected in all of the grafted sphincters. Differentiated muscle masses stained positively for alpha smooth muscle actin and myosin heavy chain at the muscle-derived stem cells injection sites.

CONCLUSIONS

This is the first study reporting that autologous muscle-derived stem cell grafts may be a tool for improving anal sphincter function.

Tissue Engineering for the Lower Urinary Tract: A Review of a State of the Art Approach

OBJECTIVES

Tissue engineering (TE) has become synonymous with physiological and functional reconstructive approaches in medicine. Although the goals of TE are ambitious and have not yet been attained, significant milestones have been achieved and future possibilities are great. To examine these possibilities with a special emphasis on the lower urinary tract, we provide a review of the development of TE techniques and a high-level overview of related regulatory and legal issues.

METHODS

Current trends in the field of TE, including the use of stem cells, scaffold optimization, and acellular tissue and growth factors, were reviewed and critically assessed through a comprehensive literature review using the PubMed database. Because of the rapid development of new TE approaches, recent abstracts from international urology conventions were included. A review of 2007 European Medicines Agency and Commission for Advanced Therapies legal regulations was also performed.

RESULTS

Although several clinical TE approaches have been developed, most lack objective validation. A variety of TE techniques are currently under development or investigation, but thus far, no one approach is clearly superior on the basis of significant long-term studies. A medical product based on TE and stem cells can be successfully developed only with careful consideration of legal and ethical regulations.

CONCLUSIONS

TE holds the promise for a tremendous impact on reconstructive urology. However, research must be focused and intensified for the full potential clinical benefits to be made widely available. Because the product development is affected by legal regulations, consensus must be achieved.

The potential of muscle-derived stem cells for stress urinary incontinence

The suburethral sling procedures, such as transvaginal tape (TVT), have recently gained popularity for the treatment of stress urinary incontinence (SUI). This TVT procedure can reinforce the weakness of pelvic floor muscles but urethral sphincter deficiency remains. Adult stem cell injection therapy for SUI has recently been at the forefront of the repair of deficient urethral function. Muscle-derived stem cells and adipose-derived stem cells are regarded as candidates for the treatment of SUI because these stem cells can be easily obtained in large quantities under local anesthesia, they have the potential to undergo long-term proliferation, self-renewal and multipotent differentiation, and can serve as a vehicle of releasing neurotrophins, such as nerve growth factor, to repair the deficient urethra.

Human muscle-derived cell injection in a rat model of stress urinary incontinence

We investigated the use of human muscle-derived cells (hMDCs) for the treatment of stress urinary incontinence (SUI) in a nude rat model. hMDCs were isolated from adult skeletal muscle. Three groups of six animals consisting of controls, animals undergoing sciatic nerve transection (SNT) with periurethral sham-injection, and SNT with hMDCs (1 x 10(6) cells/20 microl saline) were utilized. Leak point pressure (LPP) was measured 4 weeks following injection. Bilateral SNT resulted in a significantly lower LPP that was significantly higher following hMDCs than sham injection. The results demonstrate the efficacy of human muscle cell therapy alone in improving physiologic outcomes in an animal model of SUI.

The promise of stem cell therapy to restore urethral sphincter function

The promise of stem cell therapy for the treatment of stress urinary incontinence is that transplanted stem cells may undergo self-renewal and potential multipotent differentiation, leading to urethral sphincter regeneration. Cell-based therapies are most often associated with the use of autologous multipotent stem cells, such as bone marrow cells. However, harvesting bone marrow stromal stem cells is difficult, painful, and may yield low numbers of stem cells. Alternatively, autologous adult stem cells, such as muscle-derived stem cells, can be obtained in large quantities and with minimal discomfort. Not all cells and cellular therapies are the same, however, and proper placement of cells into target structures may be critical to eventual treatment success. In particular, restoration and repair of the damaged urethral sphincter is crucial to maintain urinary continence because active urethral closure is largely mediated by pudendal nerves that innervate the striated muscles and rhabdosphincter of the middle urethra.

Detection of a progesterone-dependent secretory protein synthesized by cat endometrium

Uterine flushings and culture media from endometrial explants incubated in the presence of radiolabeled amino acids were analyzed using one-(1-D) and two-dimensional (2-D) gel electrophoresis to identify proteins synthesized by the endometrium and subsequently released into the uterine lumen. 1-D and 2-D analyses of uterine flushings and culture media of endometrial explants obtained from 7- to 11-day pregnant cats (pre-implantation) showed a Mr 30,000 protein that appeared on 2-D gels as a family of macromolecules with isoelectric points between 6.5 and 7.0. This family of macromolecules was also present in the culture media of implantation-site tissue obtained from 12- to 16-day pregnant cats and of nonimplantation-site endometrium obtained form 12- to 28-day pregnant cats. The Mr 30,000 protein was absent in uterine flushings and culture media from estrous and 3- to 5-day-pregnant cats. In ovariectomized, steroid-treated animals, the Mr 30,000 protein was only detected in flushings and media from those animals treated with progesterone, regardless of the presence or absence of estradiol-priming and/or simultaneous estradiol treatment. In daily flushings obtained from ovariectomized, steroid-treated cats equipped with an indwelling uterine catheter, the Mr 30,000 protein was absent during the 14 days of estradiol treatment and was first detected 3-4 days after the onset of estradiol plus progesterone treatment. This protein was not detected in serum from estrous, 9-day pregnant, ovariectomized, and ovariectomized, steroid-treated animals. This study shows that 1) a progesterone-dependent protein, with an approximate molecular weight of 30,000 and an isoelectric point of 6.5-7.0, first appears within the uterine lumen soon after the arrival of the blastocyst and continues to be present during implantation; 2) the synthesis and release of the Mr 30,000 protein is dependent on progesterone regardless of the presence or absence of estradiol; and 3) the onset of secretion of the Mr 30,000 protein requires 3-4 days of continuous progesterone treatment in the estradiol-primed cat.