Muscle-derived cell transplantation and differentiation into lower urinary tract smooth muscle

Detrusor Underactivity in Men with Bladder Outlet Obstruction

Detrusor underactivity (DU) and bladder outlet obstruction (BOO) are both common troublesome causes of lower urinary tract symptoms (LUTS) and often impact on quality of life simultaneously in men. This article aims to focus on DU with BOO in male patients.

METHODS

Original articles concerning DU with BOO were identified through literature research from PubMed and EMBASE database. We selected 38 articles in our review, including those concerning pathophysiology, evaluation, treatment and predictors for a successful BOO surgery for DU.

RESULTS

DU from BOO can result from several pathophysiological mechanisms. Although urodynamic study (UDS) is considered as a precise method to diagnose DU and BOO, there are some previous studies which proposed a non-invasive method to identify DU related to BOO. The treatment goal of DU is restoring bladder contractility using medication or surgery. Releasing outlet obstruction and resistance is the main strategy to restore bladder contractility when medication to directly increase bladder contractility has had limited efficacy.

CONCLUSIONS

DU from BOO is poorly understood and is largely under-researched. The etiology and pathophysiology still need to be evaluated. Effective and safe medication to restore bladder contractility is also lacking. It remains valuable to perform further research to reveal the unknown aspects of DU.

Human primary muscle stem cells regenerate injured urethral sphincter in athymic rats

Background

The aim of the study was to demonstrate the efficacy of human muscle stem cells (MuSCs) isolated using innovative technology in restoring internal urinary sphincter function in a preclinical animal model.

Methods

Colonies of pure human MuSCs were obtained from muscle biopsy specimens. Athymic rats were subjected to internal urethral sphincter damage by electrocauterization. Five days after injury, 2 × 10⁵ muscle stem cells or medium as control were injected into the area of sphincter damage (n = 5 in each group). Peak bladder pressure and rise in pressure were chosen as outcome measures. To repeatedly obtain the necessary pressure values, telemetry sensors had been implanted into the rat bladders 10 days prior to injury.

Results

There was a highly significant improvement in the ability to build up peak pressure as well as a pressure rise in animals that had received muscle stem cells as compared to control (p = 0.007) 3 weeks after the cells had been injected. Only minimal histologic evidence of scarring was observed in treated rats.

Conclusion

Primary human muscle stem cells obtained using innovative technology functionally restore internal urethral sphincter function after injury. Translation into use in clinical settings is foreseeable.

Female underactive bladder - Current status and management

Underactive bladder (UAB) is defined by the International Continence Society as a symptom complex characterized by a slow urinary stream, hesitancy, and straining to void, with or without a feeling of incomplete bladder emptying sometimes with storage symptoms. Until recently, the topic has received little attention in the literature probably due to a lack of consistent definitions and diagnostic criteria. We performed a literature review to identify articles related to the diagnosis and management of UAB, specifically in female patients. UAB is a common clinical entity, occurring in up to 45% of females depending on definitions used. Prevalence increases significantly in elderly women and women who live in long-term care facilities. The exact etiology and pathophysiology for developing UAB is unknown, though it is likely a multifactorial process with contributory neurogenic, cardiovascular, and idiopathic causes. There are currently no validated questionnaires for diagnosing or monitoring treatment for patients with UAB. Management options for females with UAB remain limited, with clean intermittent catheterization, the most commonly used. No pharmacotherapies have consistently been proven to be beneficial. Neuromodulation has had the most promising results in terms of symptom improvement, with newer technologies such as stem-cell therapy and gene therapy requiring more evidence before widespread use. Although UAB has received increased recognition and has been a focus of research in recent years, there remains a lack of diagnostic and therapeutic tools. Future research goals should include the development of targeted therapeutic interventions based on pathophysiologic mechanisms and validated diagnostic questionnaires.

New therapeutic directions to treat underactive bladder

Underactive bladder (UAB) is a term used to describe a constellation of symptoms that is perceived by patients suggesting bladder hypocontractility. Urodynamic measurement that suggest decreased contractility of the bladder is termed detrusor underactivity (DUA). Regulatory approved specific management options with clinically proven ability to increase bladder contractility do not currently exist. While DUA specific treatments presumably will focus on methods to increase efficiency of bladder emptying capability relying on augmenting the motor pathway in the micturition reflex, other approaches include methods to augment the sensory (afferent) contribution to the micturition reflex which could result in increased detrusor contractility. Another method to induce more efficient bladder emptying could be to induce relaxation of the bladder outlet. Using cellular regenerative techniques, the detrusor smooth muscle can be targeted so the result is to increase detrusor smooth muscle function. In this review, we will cover areas of potential new therapies for DUA including: drug therapy, stem cells and regenerative therapies, neuromodulation, and urethral flow assist device. Paralleling development of new therapies, there also needs to be clinical studies performed that address how DUA relates to UAB.

Magnetization Transfer MR Imaging to Monitor Muscle Tissue Formation during Myogenic in Vivo Differentiation of Muscle Precursor Cells

Purpose To determine whether magnetization transfer (MT) magnetic resonance (MR) imaging may serve as a quantitative measure of the degree of fiber formation during differentiation of muscle precursor cells into engineered muscle tissue as a potential noninvasive monitoring tool in mice. Materials and Methods The study was approved by the local ethics committee (no. StV 01/2008) and the local Veterinary Office (license no. 99/2013). Human muscle progenitor cells (hMPCs) derived from rectus abdominis muscles were subcutaneously injected into CD-1 nude mice (CD-1 nude mice, Crl:CD1-Foxn1^nu; Charles River Laboratories, Wilmington, Mass) for development of muscle tissue. The mice underwent MR imaging examinations at 4.7 T at days 1, 3, 7, 14, 21, and 28 after cell transplantation by using a gradient-echo sequence with an MT prepulse and systematic variation of the off-resonance frequency (50-37 500 Hz) at an amplitude of 800°. Direct saturation was estimated from a Bloch equation simulation. The MT ratio (MTR) was correlated to immunohistochemistry findings, Western blot results, and results of myography. Data were analyzed by using one-way or two-way analysis of variance with the Sidak or Tukey multiple comparisons test. Results In the reference skeletal muscle, highest MT was found for 2500 Hz off-resonance frequency with an MTR ± standard deviation of 57.5% ± 3.5. The developing muscle tissue exhibited increasing MT values during the 28 days of myogenic in vivo differentiation and did not reach the values of native skeletal muscle. Mean values of MTR (2500 Hz) for hMPCs were 27.6% ± 6.3 (day 1), 24.7% ± 8.7 (day 3), 28.2% ± 5.7 (day 7), 35.9% ± 5.0 (day 14), 37.0% ± 7.9 (day 21), and 39.9% ± 8.1 (day 28). The results from MT MR imaging correlated qualitatively well with muscle tissue expression of specific skeletal markers, as well as muscle contractility. Conclusion MT MR imaging may be used to noninvasively monitor the process of myogenic in vivo differentiation of hMPCs as a biomarker of the quantity and quality of muscle fiber formation. ^© RSNA, 2016 Online supplemental material is available for this article.

Treatment of bladder dysfunction using stem cell or tissue engineering technique

Tissue engineering and stem cell transplantation are two important options that may help overcome limitations in the current treatment strategy for bladder dysfunction. Stem cell therapy holds great promise for treating pathophysiology, as well as for urological tissue engineering and regeneration. To date, stem cell therapy in urology has mainly focused on oncology and erectile dysfunction. The therapeutic potency of stem cells (SCs) was originally thought to derive from their ability to differentiate into various cell types including smooth muscle. The main mechanisms of SCs in reconstituting or restoring bladder function are migration, differentiation, and paracrine effects. Nowadays, paracrine effects of stem cells are thought to be more prominent because of their stimulating effects on stem cells and adjacent cells. Studies of stem cell therapy for bladder dysfunction have been limited to experimental models and have been less focused on tissue engineering for bladder regeneration. Bladder outlet obstruction is a representative model. Adipose-derived stem cells, bone marrow stem cells (BMSCs), and skeletal muscle-derived stem cells or muscle precursor cells are used for transplantation to treat bladder dysfunction. The aim of this study is to review stem cell therapy and updated tissue regeneration as treatments for bladder dysfunction and to provide the current status of stem cell therapy and tissue engineering for bladder dysfunction including its mechanisms and limitations.

Human umbilical mesenchymal stem cells-seeded bladder acellular matrix grafts for reconstruction of bladder defects in a canine model

Background

The goal of this study was to explore the feasibility of utilizing human umbilical mesenchymal stem cells (HUMSCs)-seeded Bladder acellular matrix graft (BAMG) for bladder reconstruction in a canine model.

Methodology/Principal Findings

HUMSCs were isolated from newborn umbilical cords and identified by flow cytometry. Partial cystectomy was performed in the experimental and control group. Bladder defects were repaired with HUMSCs-BAMG in the experimental group and repaired with unseeded-BAMG in control group. The implanted grafts were harvested after surgery. H&E and immunohistochemistry staining were performed to evaluate the regeneration of the bladder defect. Primary cultured HUMSCs displayed typical fibroblast morphology with spindle-shaped. Flow cytometry indicated that these cells were positive for CD105 (97.3%) and CD44 (99%), but negative for CD34 (2.8%), CD31 (2.1%), and CD45 (1.7%). Immunohistochemistry staining showed that a multilayered urothelium and well-developed smooth muscle were observed at 12 weeks in experiment group. In contrast, multilayered urothelial tissues were also observed at 12 weeks in group B, but well-developed smooth muscle bundles were observed.

Conclusions/Significance

Our preliminary results demonstrate that UMSC-seeded BAMGs are superior to unseeded BAMGs to promote the regeneration of bladder defects. Our findings indicated that HUMSCs may be a potential cell source for bladder tissue engineering.

Adipose-derived stem cells (ADSCs) and muscle precursor cells (MPCs) for the treatment of bladder voiding dysfunction

PURPOSE

Bladder outflow obstruction (BOO) is common in the elderly and can result in bladder voiding dysfunction (BVD) due to severe bladder muscle damage. The goal of this research was to evaluate the use of adult stem cells for the treatment of BVD due to decreased muscle contractility in a rat model.

MATERIALS AND METHODS

Adipose-derived stem cells (ADSCs) and muscle precursor cells (MPCs) were harvested from male Lewis rats and expanded in culture. BOO was induced by tying a suture around the urethra. Six weeks after obstruction, the development of BVD was confirmed by cystometric analysis in conscious rats, histology and molecular investigations. Injection of ADSCs or MPCs into the bladder wall and synchronous deligation was performed 6 weeks after the obstruction. After stem-cell treatment, morphological and functional changes were assessed. Age-matched rats and animals without cellular therapy but deligation-only served as controls.

RESULTS

Voiding pressures decreased progressively 6 weeks after obstruction with increased bladder capacities. Structural changes of the detrusor muscle occurred during the time of obstruction with an increased connective tissue-to-smooth muscle ratio and decreased SMA/smoothelin expression. After stem-cell injection, improved voiding pressures and voiding volumes were observed together with recovered tissue architecture. RT-PCR and Western blotting showed an up-regulation of important contractile proteins.

CONCLUSIONS

We established a reliable model for BVD and demonstrated that ADSCs and MPCs can prevent pathophysiological remodelling and provide regenerated bladder tissue and function.

Muscle Precursor Cells for the Restoration of Irreversibly Damaged Sphincter Function

Multiple modalities, including injectable bulking agents and surgery, have been used to treat stress urinary incontinence. However, none of these methods is able to fully restore normal striated sphincter muscle function. In this study, we explored the possibility of achieving functional recovery of the urinary sphincter muscle using autologous muscle precursor cells (MPCs) as an injectable, cell-based therapy. A canine model of striated urinary sphincter insufficiency was created by microsurgically removing part of the sphincter muscle in 24 dogs. Autologous MPCs were obtained, expanded in culture, and injected into the damaged sphincter muscles of 12 animals. The animals were followed for up to 6 months after injection, and urodynamic studies, functional organ bath studies, ultrastructural and histological examinations were performed. Animals receiving MPC injections demonstrated sphincter pressures of approximately 80% of normal values, while the pressures in the control animals without cells dropped and remained at 20% of normal values. Histological analysis indicated that the implanted cells survived and formed tissue, including new innervated muscle fibers, within the injected region of the sphincter. These results indicate that autologous muscle precursor cells may be able to restore otherwise irreversibly damaged urinary sphincter function clinically.

Intrasphincteric autologous myoblast injections with electrical stimulation for stress urinary incontinence

OBJECTIVE

To assess the feasibility and safety of ultrasound-guided autologous myoblast injections into the external urethral sphincter followed by electrical stimulation (ES) as a possible 2-step treatment for stress urinary incontinence (SUI).

METHODS

Autologous myoblasts isolated from a biceps muscle sample were injected under transurethral ultrasound guidance into the external urethral sphincter of 38 female patients. The patients also underwent ES postoperatively to enhance cell integration. Treatment feasibility, as well as possible intraoperative and postoperative complications, was assessed 6weeks after the injections. Additionally, the effects of the myoblast injections followed by an ES cycle were compared to those of a preoperative ES cycle undergone by the same patients.

RESULTS

No serious adverse events or complications were noted and the procedure was well tolerated. Compared with the objective and subjective measurements collected after the preoperative ES cycle, the corresponding measurements obtained 6weeks postoperatively, after the completion of a second ES cycle, indicated considerable improvement. The results to the stress test were negative for 29 (78.4%) of the patients, 5 (13.5%) considered their SUI cured, and 29 (78.4%) reported improvement.

CONCLUSION

Intrasphincteric autologous myoblast injections followed by ES is minimally invasive and feasible, and safely produced promising initial results. EU Clinical Trials EudraCT No. 2009-012389-30 ClinicalTrials.gov identifier: NCT01355133.

Mouse bladder wall injection

Mouse bladder wall injection is a useful technique to orthotopically study bladder phenomena, including stem cell, smooth muscle, and cancer biology. Before starting injections, the surgical area must be cleaned with soap and water and antiseptic solution. Surgical equipment must be sterilized before use and between each animal. Each mouse is placed under inhaled isoflurane anesthesia (2-5% for induction, 1-3% for maintenance) and its bladder exposed by making a midline abdominal incision with scissors. If the bladder is full, it is partially decompressed by gentle squeezing between two fingers. The cell suspension of interest is intramurally injected into the wall of the bladder dome using a 29 or 30 gauge needle and 1 cc or smaller syringe. The wound is then closed using wound clips and the mouse allowed to recover on a warming pad. Bladder wall injection is a delicate microsurgical technique that can be mastered with practice.

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.

Regeneration of skeletal muscle

Skeletal muscle has a robust capacity for regeneration following injury. However, few if any effective therapeutic options for volumetric muscle loss are available. Autologous muscle grafts or muscle transposition represent possible salvage procedures for the restoration of mass and function but these approaches have limited success and are plagued by associated donor site morbidity. Cell-based therapies are in their infancy and, to date, have largely focused on hereditary disorders such as Duchenne muscular dystrophy. An unequivocal need exists for regenerative medicine strategies that can enhance or induce de novo formation of functional skeletal muscle as a treatment for congenital absence or traumatic loss of tissue. In this review, the three stages of skeletal muscle regeneration and the potential pitfalls in the development of regenerative medicine strategies for the restoration of functional skeletal muscle in situ are discussed.

Characterization of smooth muscle differentiation of purified human skeletal muscle-derived cells

The purpose of this study is to characterize the smooth muscle differentiation of purified human muscle-derived cells (hMDCs). The isolation and purification of hMDCs were conducted by modified preplate technique and Dynal CD34 cell selection. Smooth muscle cell differentiation was induced by the use of smooth muscle induction medium (SMIM) and low-serum medium. The gene expressions at the mRNA and protein levels of undifferentiated and differentiated hMDCs were tested by RT-PCR, Western blot and immunofluorescence studies. Western blot and immunofluorescence studies demonstrated the purified hMDCs cultured in SMIM for 4 weeks and expressed significant amount of smooth muscle myosin heavy chain (MHC) and α-smooth muscle actin (ASMA). The cells cultured in low-serum medium for 4 weeks also expressed ASMA, while the control group did not. RT-PCR analysis showed increased gene expression of smooth muscle markers, such as ASMA, Calponin, SM22, Caldesmon, Smoothelin and MHC when purified hMDCs were exposed to SMIM for 2 and 4 weeks when compared to the controls. In conclusion, we confirmed the smooth muscle differentiation capability of purified hMDCs. The gene expression of smooth muscle differentiation of purified hMDCs was characterized. These cells may be potential biomaterials for human tissue regeneration.

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.

Bone-marrow-derived mesenchymal stem cell transplantation enhances closing pressure and leak point pressure in a female urinary incontinence rat model

PURPOSE

The purpose of this study was to determine whether periurethral injection of allogenic mesenchymal stem cells (MSCs) could increase the leak point pressure (LPP) in a rat model of stress urinary incontinence.

MATERIALS AND METHODS

Female Sprague-Dawley rats (230-240 g, n = 30) were divided into 3 groups: sham operation (group C), saline-treated (group S) and MSC-treated (group M). Bilateral pudendal nerve dissection followed by normal saline or MSC injection on both sides of the urethra was done. LPP and closing pressure (CP) testing was performed after the treatment. The specific markers for smooth muscle cells in the transplantation sites of the urethra were determined.

RESULTS

Both the LPP and CP were significantly lower in group S than controls. However, these were restored to the control values in group M (p < 0.05). The LPPs of groups C, S and M were 29.1 ± 2.1, 22.0 ± 2.2 and 43.1 ± 3.2 cm H(2)O, respectively. The CPs of groups C, S and M were 27.1 ± 3.1, 21.1 ± 3.2, and 32.1 ± 2.1 cm H(2)O, respectively. The injected MSCs stained positive for muscle-specific markers.

CONCLUSION

This study suggests that MSCs might differentiate into muscle lineage cells and may contribute to the repair of damaged muscle tissue.

Advances in stem cell therapy for the lower urinary tract

Lower urinary tract diseases are emotionally and financially burdensome to the individual and society. Current treatments are ineffective or symptomatic. Conversely, stem cells (SCs) are regenerative and may offer long-term solutions. Among the different types of SCs, bone marrow SCs (BMSCs) and skeletal muscle-derived SCs (SkMSCs) have received the most attention in pre-clinical and clinical trial studies concerning the lower urinary tract. In particular, clinical trials with SkMSCs for stress urinary incontinence have demonstrated impressive efficacy. However, both SkMSCs and BMSCs are difficult to obtain in quantity and therefore neither is optimal for the eventual implementation of SC therapy. On the other hand, adipose tissue-derived SCs (ADSCs) can be easily and abundantly obtained from "discarded" adipose tissue. Moreover, in several head-on comparison studies, ADSCs have demonstrated equal or superior therapeutic potential compared to BMSCs. Therefore, across several different medical disciplines, including urology, ADSC research is gaining wide attention. For the regeneration of bladder tissues, possible differentiation of ADSCs into bladder smooth muscle and epithelial cells has been demonstrated. For the treatment of bladder diseases, specifically hyperlipidemia and associated overactive bladder, ADSCs have also demonstrated efficacy. For the treatment of urethral sphincter dysfunction associated with birth trauma and hormonal deficiency, ADSC therapy was also beneficial. Finally, ADSCs were able to restore erectile function in various types of erectile dysfunction (ED), including those associated with diabetes, hyperlipidemia, and nerve injuries. Thus, ADSCs have demonstrated remarkable therapeutic potentials for the lower urinary tract.

Bladder reconstruction with adipose-derived stem cell-seeded bladder acellular matrix grafts improve morphology composition

PURPOSE

To assess the feasibility of seeding adipose-derived stem cells (ADSCs) onto bladder acellular matrix grafts (BAMGs) for bladder reconstruction in a rabbit model.

METHODS

Autologous ADSCs were isolated, expanded and identified by flow cytometry. In the experimental group, ADSCs were seeded onto BAMGS for reconstructing bladder defects in 12 male rabbits. Unseeded BAMGs were used for bladder reconstruction in the control group of 12 rabbits. Cystography was performed at 4, 12 and 24 weeks after grafts implantation. Following cystography, the animals were killed and grafts were harvested; H&E and immunohistochemical staining were performed with cytokeratin AE1/AE3, smooth muscle alpha-actin and S-100 markers.

RESULTS

Flow cytometry demonstrated that the ADSCs expressed CD90, CD44, CD105, CD166 and CD34, but not CD45 or CD106. The cells demonstrated good biocompatibility with BAMGs. At 24 weeks, in the experimental group, the reconstructed bladders reached a mean volume of 94.68 +/- 3.31% of the pre-cystectomy bladder capacity. Complete regeneration of smooth muscle and nerve tissue was evident. Regenerated SMCs, urothelium and nerve cells stained positively for alpha-smooth muscle actin, AE1/AE3 and S-100. In the control group, the mean bladder volume was 69.33 +/- 5.05% of the pre-cystectomy volume; histologically, the control group was characterized by multi-layered urothelium without evidence for organized muscle or nerve tissue.

CONCLUSIONS

These data demonstrate that seeding ADSCs onto BAMGs promote regeneration of smooth muscle and nervous tissue regeneration in a rabbit model. This compound graft was more suitable for bladder reconstruction than BAMG alone.

Mature, adipocyte derived, dedifferentiated fat cells can differentiate into smooth muscle-like cells and contribute to bladder tissue regeneration

PURPOSE

We recently reported that mature, adipocyte derived, dedifferentiated fat cells show high proliferative activity and multilineage differentiation potential. In the current study we investigated whether such cells could differentiate into a smooth muscle cell lineage and contribute to bladder tissue regeneration in a mouse bladder injury model.

MATERIALS AND METHODS

Human adipocyte derived dedifferentiated fat cells were cultured for 1 week under conditions favorable for smooth muscle cell differentiation and immunostained for alpha-smooth muscle actin. The expression of smooth muscle cell marker genes for differentiating dedifferentiated fat cells was measured by real-time reverse transcription-polymerase chain reaction. Green fluorescence protein labeled dedifferentiated fat cells were injected into cryo-injured bladder walls in mice. The ability of the fat cells to regenerate smooth muscle tissue was examined immunohistochemically 14 and 30 days after transplantation.

RESULTS

Immunohistochemical analysis revealed that more than 50% of the fat cells were successfully differentiated into alpha-smooth muscle actin positive cells under the optimum culture condition of a medium containing 5% fetal bovine serum and 5 ng/ml transforming growth factor-beta1. Real-time reverse transcription-polymerase chain reaction revealed increased expression of SM22alpha, alpha-smooth muscle actin and smooth muscle-myosin heavy chain in dedifferentiated fat cells during week 1 of differentiation culture. Cells expressing alpha-smooth muscle actin plus green fluorescence protein were observed at the bladder wall injection sites in mice 14 and 30 days after transplantation. Alpha-smooth muscle actin positive areas in injured bladder tissue in mice with fat cell injection were significantly larger than those in saline injected control mice.

CONCLUSIONS

These findings suggest that dedifferentiated fat cells can differentiate into smooth muscle cell lineages and contribute to the regeneration of bladder smooth muscle tissue.

Isolation and characterization of human muscle-derived cells

OBJECTIVES

To isolate and characterize human muscle-derived cells (MDCs) for future management applications on lower urinary tract symptoms, including stress urinary incontinence and bladder reconstitution. The development of muscle stem cells for transplantation or gene transfer in patients with muscle disorders has become more attractive and challenging recently.

METHODS

Human MDCs were isolated from the skeletal muscles of the limbs. The muscle tissues were minced, digested at 37 degrees C by 0.2% collagenase, trypsinized, filtered, and cultured in F12 medium with 15% fetal bovine serum at 37 degrees C. Human MDCs were then isolated using a modified preplate technique. After isolation, the MDCs were characterized by immunohistochemistry, flow cytometry, and indirect immunofluorescence.

RESULTS

The growth doubling time of the MDCs was approximately 24 hours. Immunohistochemistry study was performed with the stem cell markers CD34, CD117, vascular cell adhesion molecule, and vascular endothelial growth factor receptor 2, and the relative stem cell position was identified. Positive immunofluorescence outcomes were found with the stem cell markers, myoblast markers CXCR4, CD56, desmin, and a fibroblast marker AB-1. Flow cytometry analysis identified markers CD34 and CD56 in the isolated MDCs, with a percentage of 5.12% and 10.34%, respectively.

CONCLUSIONS

The isolation and characterization of human MDCs was successfully achieved. Human MDCs might have the potential to be a novel tool for the management of stress urinary incontinence and bladder reconstitution.

Optimization of human skeletal muscle precursor cell culture and myofiber formation in vitro

Muscle bioengineering is proposed as a treatment option for various conditions requiring restoration of muscle function. In order to allow for rapid clinical translation culture conditions have to be optimized for human application. The optimal isolation and culture technique should be able to support cell growth and differentiation using defined media only. Therefore, we have evaluated alternative culture conditions to determine the optimal growth condition for the engineering of human skeletal muscle. In this research, we present protocols for consistent isolation and growth of human muscle precursor cells (MPCs). MPCs were grown from human biopsies and expanded in culture using defined media and collagen coated dishes only. The best results were achieved using a one-step pre-plating and by supplementing the growth medium with insulin, dexamethasone, human basic fibroblast growth factor (hFGF) and human epithelial growth factor (hEGF). Detailed cell characterization using fluorescence-activated cell-sorting analysis and morphological analysis at different passages were performed. Further, the applicability of these cells for tissue engineering purposes was assessed by measuring expansion potential, formation of myofibers and fused myotubes. We have established a culture technique for human MPCs that allows for reliable cell growth and expansion using collagen coated dishes and defined media only. Cell characterization demonstrated a muscle phenotype and the ability to form myofibers in vitro.

Can autologous myoblasts be used as a potential bulking agent?

OBJECTIVE

To investigate the behaviour of donor myoblasts at the vesico-ureteric junction (VUJ) and to evaluate their potential as an autologous bulking agent, as myoblast transplantation has been shown to regenerate damaged or degenerated tissue, and it was postulated that they could be used to treat vesico-ureteric reflux.

MATERIALS AND METHODS

Muscle biopsies were obtained from the lower limb muscles of 10 pigs. The quality of the cells was evaluated by electrophysiological and immunohistochemical tests. The cell membranes of myoblasts were labelled with PKH26, a fluorescent dye. Six weeks after taking of the muscle biopsies all pigs underwent cell transplantation; 30 x 10(6) cells suspended in transplantation medium (in 1-mL syringes) were injected at the VUJ, into the proximal urethra and the rhabdosphincter. At the VUJ volumes of 1 mL were injected, whereas in the urethra and rhabdosphincter small cell depots (0.1 mL) were injected. All the pigs were killed 8 weeks later, and the myoblasts and newly formed myofibres were identified using fluorescence microscopy, with a histological evaluation and investigation of potential local inflammatory reaction.

RESULTS

Two to three intact layers of autologous myoblasts were found in the outer aspects of the large cell depots in the VUJ. Immunohistochemistry further showed that the myoblasts were only viable at these outermost borders of the large bulking areas, whereas necrosis with red fluorescent cell detritus was visible in the remaining central aspects of the large bulk of cells. By contrast, cells survived and formed myotubes in the wall of the proximal urethra and the rhabdosphincter where the small cell depots had been injected.

CONCLUSIONS

In small depots, transplanted autologous myoblasts can survive and differentiate into myofibres, while in a large bulk of cells the vast majority of cells become necrotic. The present results show that myoblasts cannot be used for augmentation of large volumes of tissue or as a bulking agent.

Treatment of experimental injury of anal sphincters with primary surgical repair and injection of bone marrow-derived mesenchymal stem cells

PURPOSE

Sphincter injury is a common cause of anal incontinence. Surgical repair remains the operation of choice; however, the outcome often is poor. We investigated the ability of injected bone marrow-derived mesenchymal stem cells to enhance sphincter healing after injury and primary repair in a preclinical model.

METHODS

Twenty-four inbred Wistar Furth rats were divided into three groups. As a control, Group A underwent sham operation. Group B had sphincterotomy and repair of both anal sphincters plus saline injections. The study group (Group C) underwent sphincterotomy and repair followed by intrasphincteric injections of syngenic bone marrow-derived mesenchymal stem cells. A further group (Group D) of outbred Wistar rats treated with mesenchymal stem cells and immunosuppressive therapy also was evaluated. At 30 days, histologic and morphometric analysis and in vitro contractility testing was performed.

RESULTS

A significant decrease of muscle tissue was observed at the site of repair after sphincter injury. However, in Groups C and D, histologic examination demonstrated new muscle fibers and morphometric analysis revealed a significantly greater muscle area fraction than in Group B (P < 0.05). Moreover, mesenchymal stem cells injection improved contractility of sphincters strips compared with Group B (P < 0.05). No significant differences were found between Groups C and D.

CONCLUSIONS

In our experimental model, bone marrow-derived mesenchymal stem cells injection improved muscle regeneration and increased contractile function of anal sphincters after injury and repair. Therefore, mesenchymal stem cells may represent an attractive tool for treating anal sphincter lesions in humans. Investigations into the biologic basis of this phenomenon should increase our knowledge on underlying mechanisms involved in sphincter repair.

Improvement of urethral sphincter deficiency in female rats following autologous skeletal muscle myoblasts grafting

Sphincteric deficiency is the most common cause of urinary incontinence in humans. Various treatments have lead to disappointing results due to a temporary benefit. Recent studies raised the possibility that sphincteric deficiency could be treated by implanting skeletal myoblasts. In the present study, we developed in the female rat a model of chronic sphincteric defect to assess the benefit of myoblast injection. Sphincter deficiency was induced by freezing, longitudinal sphincterotomy, and notexin injection, respectively, to obtain a reproducible and irreversible incontinence. Autologous tibialis anteriors were cultured to be injected in the best model. Functional results were evaluated by measuring the urethral pressure with an open catheter. Histology was performed in the excised urethras. Of the three techniques, only longitudinal sphincterotomy caused definitive incontinence by irreversibly destroying the striated sphincter muscle fibers: a 45% decrease of the closure pressure was observed 21 days after the sphincterotomy. At this time, we injected myoblasts at the sphincterotomy site. In the sham-injected group (n = 18), the closure pressure decrease was not significantly modified 21 days after injection. By comparison, a return to near normal value was observed after cell grafting (n = 21). These results and those obtained by others strongly suggest that the use of myoblasts could be a potential innovative therapy for urethral deficiencies leading to incontinence.

Functional and Histological Changes after Myoblast Injections in the Porcine Rhabdosphincter

OBJECTIVE

Transurethral ultrasound-guided injection of autologous myoblasts has recently been shown to cure urinary stress incontinence. In the present study, the dose-dependent changes in maximal urethral closure pressures after application of myoblasts were investigated in a porcine animal model.

METHODS

Myoblast cultures were grown from a porcine muscle biopsy. The biopsy was enzymatically dissociated by using a modified cell dispersion technique. Single myoblasts in suspension were manually collected with a micropipette under microscopic control. Next a clonal myoblast culture was prepared. Before the cells were applied, fluorescence labelling (PKH) was used to assess integration of the injected myoblasts into the rhabdosphincter. With the help of a transurethral ultrasound probe (23 F, 11 MHz) and a special injection system, the myoblasts were injected into the rhabdosphincter of five pigs under direct sonographic control. Into two different areas of the rhabdosphincter, increasing different cell counts were injected (total volume 1.5 ml). At each area, 10 depots of 150 microl volume were injected all along the rhabdosphincter. The following cell counts were used: 1.5 x 10(6), 2.1 x 10(6), 4.2 x 10(6) (low range) 5.69 x 10(6), 8.1 x 10(6), 1.13 x 10(7), 1.6 x 10(7) (mid range) 2.26 x 10(7), 4.4 x 10(7), and 7.8 x 10(7) (high range). To avoid possible cell rejection, we immunosuppressed the pigs with daily cortisone (1g Solu Dacortin) because allogenic myoblasts were used. Urethral pressure profiles (UPPs) were measured before and 3 wk postoperatively before the pigs were put to sleep. The lower urinary tract was removed in all pigs for histological analysis.

RESULTS

Histological examination of the specimens revealed that the injected cells had survived at the injection site and had formed new myofibres. Overall the UPP curves revealed dose-dependent changes. Statistically significant increased pressure values of up to more than 300% could be observed in all cases in which higher concentrations of cells had been applied. Increases were also noted in mid range concentrations although not to such a high extent (approximately 150%). Pressure values had even diminished (approximately 50%) after injecting the three lowest concentrations (1.5 x 10(6), 2.1 x 10(6), 4.2 x 10(6)).

CONCLUSIONS

The present results show that the effects after application of myoblasts into the rhabdosphincter are dose-dependent.

Changing concepts of bladder regeneration

During the last decade, there has been a dramatic increase in studies aimed at regeneration of the urinary bladder. Many studies employed animal-derived or synthetic materials as grafts for experimental bladder augmentation models, with or without additional measures to promote regeneration, such as autologous cell transplantation or growth factor loading. However, in spite of encouraging results in several reports, few methodologies have shown proven definitive clinical utility. One major problem in these studies is the lack of a clear distinction between native and regenerated bladder in total bladder function after augmentation. Another crucial problem is the absorption and shrinkage of larger grafts, which may result from insufficient vascular supply and smooth muscle regeneration. In contrast, researchers have recently attempted to establish alternative regenerative strategies for treating bladder diseases, and have employed far more diverse approaches according to the various pathological conditions to be treated. For total replacement of the bladder after cystectomy for invasive bladder cancer, urothelium-covered neobladder with non-urinary tract backbone remains a viable choice. In addition, functional bladder diseases such as urinary incontinence, weak detrusor, or non-compliant fibrotic bladder have also been major targets for many leading research groups in this field. These conditions are studied much more from different therapeutic standpoints, aiming at the prevention or reversal of pathological conditions in muscle remodeling or neural control. Such altered research direction would inevitably lead to less surgically based basic biological research, and also would include a far wider spectrum of adult and pediatric bladder diseases, from overactive bladder to dysfunctional voiding.

Gene therapy used for tissue engineering applications

This review highlights the advances at the interface between tissue engineering and gene therapy. There are a large number of reports on gene therapy in tissue engineering, and these cover a huge range of different engineered tissues, different vectors, scaffolds and methodology. The review considers separately in-vitro and in-vivo gene transfer methods. The in-vivo gene transfer method is described first, using either viral or non-viral vectors to repair various tissues with and without the use of scaffolds. The use of a scaffold can overcome some of the challenges associated with delivery by direct injection. The ex-vivo method is described in the second half of the review. Attempts have been made to use this therapy for bone, cartilage, wound, urothelial, nerve tissue regeneration and for treating diabetes using viral or non-viral vectors. Again porous polymers can be used as scaffolds for cell transplantation. There are as yet few comparisons between these many different variables to show which is the best for any particular application. With few exceptions, all of the results were positive in showing some gene expression and some consequent effect on tissue growth and remodelling. Some of the principal advantages and disadvantages of various methods are discussed.

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

OBJECTIVES

To compare muscle-derived cells (MDCs) and fibroblasts with regard to their potential for restoration of urethral function on injection in a previously established animal model of stress urinary incontinence.

METHODS

The animals were divided into four (dosage) or five (cell concentration) experimental groups: normal, nontreated controls (normal group) or bilateral sciatic nerve transection with either periurethral injection of saline (saline group), MDCs (MDC group), fibroblasts (fibroblast group), or MDC/fibroblast mixture (mixed group). At 4 weeks after injection, the leak point pressure (LPP) was measured and contractility testing and histologic analysis were performed.

RESULTS

The histologic examination demonstrated muscular atrophy in the saline group and new striated muscle fibers at the sites of MDC injection in the MDC group, but not in the fibroblast group. Denervation of the urethra resulted in a significant decrease of maximal fast-twitch muscle contraction amplitude to only 9% of normal. MDC injection into the denervated urethra significantly improved the fast-twitch muscle contraction amplitude to 73% of normal. The LPP of the normal, saline, MDC, fibroblast, and mixed groups at 4 weeks after treatment was 43.3 +/- 2.5, 25.8 +/- 1.4, 38.2 +/- 4.2, 38.3 +/- 1.2, and 34.5 +/- 3.3 cm H2O, respectively. In the cell dosage experiment, the LPP increased with increases in the injected cell number. Evidence of obstruction was observed in the high-dose (1 x 10(7) cells) fibroblast group.

CONCLUSIONS

Although both MDCs and fibroblast injection increased the LPP in a stress urinary incontinence rat model, only MDCs significantly improved urethral muscle strip contractility. Moreover, urinary retention developed with high-dose fibroblast injection, but not with MDC injection.

Injection of skeletal muscle-derived cells into the penis improves erectile function

We investigated the effect of intrapenile injection of muscle-derived cells (MDC) on the erectile function in rats with bilateral cavernous nerve injury. Rat MDC were harvested and transduced with a retrovirus expressing the lacZ gene. Hanks' balanced salt solution (HBSS) (20 microl) or MDC (1 x 10(6) cells/side) were injected in each corpora cavernosa immediately before bilateral cavernous nerve transection. Intracavernous pressures (ICP) were measured 2 or 4 weeks after surgery with electrical stimulation of the pelvic nerves. Mean maximal ICP of sham group was significantly lower than that of control group both at 2 and 4 weeks after surgery. When MDC were injected into the penis, ICP improved over the sham-injected group at both 2 and 4 weeks after surgery. Percent area of PGP 9.5 staining was significantly greater in MDC-injected penis than in sham-injected at 2 and 4 weeks. Penile MDC injection can facilitate recovery of injured penile innervation and improve erectile function.

Fate of implanted syngenic muscle precursor cells in striated urethral sphincter of female rats: perspectives for treatment of urinary incontinence

OBJECTIVES

To analyze the outcome of syngenic skeletal muscle precursor cells (MPCs) after implantation in the striated urethral sphincter of the female rat.

METHODS

MPCs were isolated from the striated muscles of the lower limbs and infected with a retrovirus carrying the gene for green fluorescent protein. Approximatively 10(5) cells were injected longitudinally in the striated urethral sphincter of 24 animals using a 10-muL Hamilton syringe. The whole urethra was excised at 0, 1, 7, 10, 14, 30, and 90 days after implantation for histologic study and fluorescence analysis of the transections.

RESULTS

At days 0 and 1, some small, round, fluorescent MPCs were observed at the injection site. At day 7, significant MPC persistence was noted, with infiltration of inflammatory cells in the whole urethral wall (striated muscle layer, smooth muscle layer, and connective tissue). At day 10, some fusiform cells appeared in the striated muscle layer, suggesting the incorporation of MPCs into the striated myofibers. Inflammatory cells were no longer visible. At day 14, the fusiform cells tended to be larger. The small, round cells were no longer seen. At days 30 and 90, all myofibers of the striated muscle layer were strongly fluorescent, and no fluorescence was detectable in the smooth muscle layer.

CONCLUSIONS

Implantation of skeletal MPCs in the urethral sphincter resulted in selective incorporation into striated myofibers. Muscle-derived cell autografting could represent a new approach for the treatment of urinary incontinence in humans.

Therapy Insight: sexual and bladder dysfunction associated with diabetes mellitus

Diabetes mellitus affects 3-6% of the population. Patients with diabetes experience chronic vascular complications, which lead to a wide range of medical problems. Genitourinary problems are included among these complications, related to both neuropathy and vasculopathy. The most important clinical features relating to genitourinary involvement in patients with diabetes include erectile dysfunction (ED) and retrograde ejaculation in men, and bladder dysfunction. There is a 36% prevalence of ED in men with diabetes, which is about three times higher than in the general population. With so many other factors contributing to the risk of developing ED, it is important that men with diabetes are advised not only regarding glycemic control, but also in relation to lifestyle factors that might contribute to the development of ED, such as smoking. Diabetes-associated bladder dysfunction, characterized by decreased bladder sensation, increased bladder capacity, and impaired detrusor contractility, is another important condition to consider when treating patients with diabetes. Accurate assessment is important in these patients in order to reduce the damage associated with neurogenic bladder dysfunction. Management goals for these patients include voiding strategies for relief of symptoms, prevention and treatment of infections, continence, and adequate bladder emptying. This review discusses the mechanisms behind urologic conditions that are often encountered when treating patients with diabetes, and summarizes the evaluation and management of these patients.

Neurologic recovery and improved detrusor contractility using muscle-derived cells in rat model of unilateral pelvic nerve transection

OBJECTIVES

To create a model of peripheral neuropathy and explore the potential of using muscle-derived cells (MDCs) to facilitate the regeneration of autonomic nerves and improve bladder function. Damage to the peripheral nerves that innervate the bladder from radical pelvic surgery is refractory to the currently available treatments.

METHODS

Rat MDCs were isolated from the gastrocnemius muscle using the preplate technique. The unilateral pelvic nerve was cut in female Sprague-Dawley rats. Three experimental groups were included: control (n = 5); unilateral pelvic nerve transected with sham injection (n = 5); and unilateral pelvic nerve transected with injection of MDC (3 x 10(5) cells/site; n = 5). Two weeks after injection, the intravesical pressures were measured during electrical stimulation of the proximal transected preganglionic nerve. The contralateral major pelvic ganglion was excised to ensure that any observed bladder activity was due exclusively to inputs on the unilateral side. The rats were killed, the experimental side major pelvic ganglion was removed, and enkephalin immunoreactivity was counted.

RESULTS

After unilateral pelvic nerve transection, no change occurred in bladder weight or capacity or postvoid residual urine volume. The maximal intravesical pressures for the control, sham, and MDC groups, after the contralateral pelvis had been cut, was 31.7 +/- 10.3, 9.6 +/- 4.5, and 15.2 +/- 7.7 cm H2O, respectively (P <0.05). After transecting the preganglionic pelvic nerve, the intensity of pericellular enkephalin immunoreactivity varicosities was significantly decreased in the sham group but unchanged in the MDC group compared with the control group.

CONCLUSIONS

MDCs can promote peripheral autonomic nerve regeneration. The morphologic changes correlated with the functional neurologic recovery effect of MDCs. The underlying neurologic recovery mechanisms of MDCs need to be exploited.

Biaxial mechanical properties of muscle-derived cell seeded small intestinal submucosa for bladder wall reconstitution

Bladder wall replacement remains a challenging problem for urological surgery due to leakage, infection, stone formation, and extensive time needed for tissue regeneration. To explore the feasibility of producing a more functional biomaterial for bladder reconstitution, we incorporated muscle-derived cells (MDC) into small intestinal submucosa (SIS) scaffolds. MDC were harvested from mice hindleg muscle, transfected with a plasmid encoding for beta-galactosidase, and placed into single-layer SIS cell culture inserts. Twenty-five MDC and/or SIS specimens were incubated at 37 degrees C for either 10 or 20 days. After harvesting, mechanical properties were characterized using biaxial testing, and the areal strain under 1 MPa peak stress used to quantify tissue compliance. Histological results indicated that MDC migrated throughout the SIS after 20 days. The mean (+/-SE) areal strain of the 0 day control group was 0.182 +/- 0.027 (n=5). After 10 days incubation, the mean (+/-SE) areal strain in MDC/SIS was 0.247 +/- 0.014 (n=5) compared to 10 day control SIS 0.200 +/- 0.024 (n=6). After 20 days incubation, the mean areal strain of MDC/SIS was 0.255 +/- 0.019 (n=5) compared to control SIS 0.170 +/- 0.025 (n=5). Both 10 and 20 days seeded groups were significantly different (p=0.027) than that of incubated SIS alone, but were not different from each other. These results suggest that MDC growth was supported by SIS and that initial remodeling of the SIS ECM had occurred within the first 10 days of incubation, but may have slowed once the MDC had grown to confluence within the SIS.

Embryonale und adulte Stammzellen f�r Tissue Engineering in der Urologie

Stem cells are considered a possible alternative treatment for degenerative diseases. Parkinson's disease and diabetes mellitus may become curable using stem cells. The term "stem cell" is used very broadly, although it has been well defined. Undifferentiated cells (stem cells and progenitor cells) are isolated from prenatal and postnatal tissues. This review provides an overview of embryonic and adult stem cells and describes potential applications in the field of tissue engineering in urology.

Diagnosis and treatment of voiding symptoms

Lower urinary tract symptoms (LUTS) are associated with lower urinary tract dysfunction. Symptoms are the subjective indicator of a disease or change in condition as perceived by the patient, caregiver, or partner and may lead the individual to seek help from health care professionals. LUTS are usually qualitative and, therefore, cannot usually be used to make a definitive diagnosis. LUTS also can indicate pathologies other than lower urinary tract dysfunction, such as urinary infection. LUTS are divided into 7 groups: storage, voiding (obstructive), postmicturition symptoms and 4 others. Voiding symptoms, which are caused by lower urinary tract obstruction, include slow stream, splitting or spraying, intermittency, hesitancy, straining, and terminal dribble. Postmicturition symptoms, which are experienced immediately after micturition, consist of the feeling of incomplete emptying and postmicturition dribble. Postmicturition dribble describes the involuntary loss of urine immediately after the individual has finished passing urine; in men, usually after leaving the toilet and in women, after rising from the toilet. Hence, postmicturition dribble is elicited by different situations or is considered as having different implications. For example, although postmicturition dribble usually implies incomplete emptying (voiding symptoms) in elderly men with benign prostatic hyperplasia, postmicturition dribble is often considered as urinary incontinence (a storage symptom) in many patients, even with bladder outlet obstruction. In such cases, detailed history taking and further evaluation, such as urinary flowmetry, postvoid residual volume, and comprehensive urodynamic evaluation, should be performed as appropriate. If no urodynamic abnormalities of either the detrusor or the outlet can be detected despite significant LUTS, factors unrelated to the lower urinary tract may be responsible for the voiding symptoms.

Muscle-derived stem cells seeded into acellular scaffolds develop calcium-dependent contractile activity that is modulated by nicotinic receptors

OBJECTIVES

To explore the contractile activity and physiologic properties of muscle-derived stem cells (MDSCs) incorporated into small intestinal submucosa (SIS) scaffolds.

METHODS

MDSCs were harvested from mice hind leg muscles using the preplate technique and stably transfected with a plasmid to express the LacZ reporter gene. Fifty different preparations of SIS cultured with MDSCs (MDSC/SIS) or SIS alone were incubated at 37 degrees C for 1, 4, and 8 weeks and also were mounted in a bath to measure the isometric contractions.

RESULTS

LacZ and Masson-trichrome staining revealed MDSCs could migrate into and distribute throughout the SIS and form myotubes. In MDSC/SIS, spontaneous contractile activities were noted in the 4-week (five of six specimens) and 8-week (eight of eight specimens) cultures, but not in 1-week cultures (n = 11). All SIS control groups after 1 (n = 11), 4 (n = 6), and 8 (n = 8) weeks of incubation did not show any activity. In most of the 4-week, and all of the 8-week, MDSC/SIS cultures, the frequency and amplitude of spontaneous contractile activities were decreased by succinylcholine 10 microM and 20 microM. Electrical field stimulation, carbachol, and KCl did not alter the frequency, amplitude, or pattern of spontaneous contractile activities in MDSC/SIS. Spontaneous contractile activities were blocked by Ca(32+)-free Krebs solution with ethyleneglycoltetraacetic acid 200 microM and distilled water.

CONCLUSIONS

MDSCs could be incorporated into SIS-forming myotubes capable of contracting. The contractile activity of this three-dimensional construct is Ca(2+) dependent and is modulated by nicotinic receptors. MDSC seeding of an acellular matrix may become a functional sling to reengineer the deficient sphincter or as contractile bladder augmentation.

Tissue engineering in urology: where are we going?

Tissue engineering in urology is a broad term used to describe the development of alternative tissue sources for diseased or dysfunctional native urologic tissue. This article reviews the recently published techniques involving synthetic and natural biodegradable matrices alone, known as "unseeded" scaffolds, and the latest data on "seeded" scaffolds, which are impregnated with cultured cells from urologic organs. Recent discoveries in reporter gene labeling of urologic tissue are discussed as a new method to identify and track the fates of these transplanted cells in vivo. This article also investigates how these bioengineering techniques are applied to synthetic and natural scaffolds, such as polyglycolic acid and porcine small intestine submucosa, to increase bladder capacity, repair urethral strictures, and replace corporal plaques in Peyronie's disease. Furthermore, recently published reports that these materials have been seeded with chondrocytes to create corporal rods for penile prostheses and stents for ureteral and urethral stricture disease are discussed. With these latest developments as a foundation, the future directions of tissue engineering in urology are presented.

Recent advances in and therapeutic potential of muscle-derived stem cells

Over the past few years, issues related to the commitment and potential of reservoir precursor cells that reside in most tissues have been revisited. Many reports have documented either plasticity or de-differentiation of a number of precursor cells isolated from several tissues, including bone marrow, brain, and skeletal muscle. These findings have challenged the dogma that mononuclear cells derived from adult, post-mitotic tissues can differentiate and contribute only to the tissue from which they originate. Thus, much current research in stem cells is testing the therapeutic potential of these cells to deliver normal genes and their encoded proteins into damaged or injured tissues. This review will focus on muscle-derived precursor cells and their apparently heterogeneous nature and summarize some of the most recent findings and hypotheses on their characterization and practical use.

Current and future pharmacological treatment for overactive bladder

PURPOSE

Urinary incontinence and overactive bladder are important and common conditions that have received little general medical attention. We reviewed the magnitude and impact of these conditions, and discuss pharmacotherapy as well as new drugs under investigation.

MATERIALS AND METHODS

The main emphasis of this review is pharmacological therapy for the bladder. We discuss currently available agents, drugs under development and pharmacological targets that would be suitable targets for treating overactive bladder. Drugs such as duloxetine that target not bladder smooth muscle, but rather central nervous system control of the micturition reflex are undergoing clinical trials. We also discuss intravesical therapy and alternative drug delivery methods, such as intravesical capsaicin and botulinum toxin, with special emphasis on approaches to modulate bladder afferent nerve function for preventing overactive bladder.

RESULTS

There are many advantages to advanced drug delivery systems, including long-term therapeutic efficacy, decreased side effects and improved patient compliance. Future speculation such as gene therapy holds great promise for overactive bladder because it is possible to access all genitourinary organs via endoscopy and other minimally invasive techniques that are ideally suited for gene therapy.

CONCLUSIONS

Traditional anticholinergic therapies are limited in their effectiveness. There is great hope for future research regarding voiding dysfunction and urinary incontinence through a focus on afferent nerve intervention for preventing overactive bladder.

Bladder instability: a re-appraisal of classical experimental approaches and development of new therapeutic strategies

1 Despite the growing social interest in human urinary tract disorders, the aetiology of detrusor instability remains poorly understood. Myogenic and neural impairment of detrusor activity caused by CNS or autonomic injuries can results in dysfunctions of normal voiding of the bladder such as urinary incontinence. 2 The contractility of human detrusor smooth muscle is critically dependent on acetylcholine-induced muscarinic receptor activation. Biochemical and functional in vivo and in vitro studies suggest the presence of an heterogeneous population of muscarinic receptor subtypes (M1-M4) localized at muscular and neutral sites. There is increasing evidence on the prejunctional auto- and hetero-regulation of acetylcholine release from parasympathetic nerve endings in modulating detrusor muscle contraction during micturition. 3 Activation of P2X purinoreceptors closely associated with the parasympathetic varicosities seems to be implicated to varying extent in the contractility in normal or instable human detrusor. Interestingly, P2X(1) subtype expression on smooth muscle increases considerably in the symptomatically obstructed bladder. A striking absence of P2X(3) and P2X(5) subtypes was observed in the cholinergic innervation of detrusor from patients with urgent incontinence. Thus, it is likely that alteration of the neural acetylcholine control can play a critical role in pathological states. 4 If the failures in storage and voiding can be recognized urodynamically, considerable difficulties remain in investigating the underlying functional changes especially because the study of the pathophysiology requires techniques that can be justified in animals but not in humans. 5 Recently, to solve this problem an alternative technique using human smooth muscle cells in culture has been developed. Human cell lines may be relevant in investigating the molecular pathways in physiological and pathological conditions. 6 The potential development of novel molecular therapeutic strategies such as gene therapy and tissue engineering is also discussed.

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.