Autologous primary muscle-derived cells transfer into the lower urinary tract

Exosome biopotentiated hydrogel restores damaged skeletal muscle in a porcine model of stress urinary incontinence

Urinary incontinence afflicts up to 40% of adult women in the United States. Stress urinary incontinence (SUI) accounts for approximately one-third of these cases, precipitating ~200,000 surgical procedures annually. Continence is maintained through the interplay of sub-urethral support and urethral sphincter coaptation, particularly during activities that increase intra-abdominal pressure. Currently, surgical correction of SUI focuses on the re-establishment of sub-urethral support. However, mesh-based repairs are associated with foreign body reactions and poor localized tissue healing, which leads to mesh exposure, prompting the pursuit of technologies that restore external urethral sphincter function and limit surgical risk. The present work utilizes a human platelet-derived CD41a and CD9 expressing extracellular vesicle product (PEP) enriched for NF-κB and PD-L1 and derived to ensure the preservation of lipid bilayer for enhanced stability and compatibility with hydrogel-based sustained delivery approaches. In vitro, the application of PEP to skeletal muscle satellite cells in vitro drove proliferation and differentiation in an NF-κB-dependent fashion, with full inhibition of impact on exposure to resveratrol. PEP biopotentiation of collagen-1 and fibrin glue hydrogel achieved sustained exosome release at 37 °C, creating an ultrastructural “bead on a string” pattern on scanning electron microscopy. Initial testing in a rodent model of latissimus dorsi injury documented activation of skeletal muscle proliferation of healing. In a porcine model of stress urinary incontinence, delivery of PEP-biopotentiated collagen-1 induced functional restoration of the external urethral sphincter. The histological evaluation found that sustained PEP release was associated with new skeletal muscle formation and polarization of local macrophages towards the regenerative M2 phenotype. The results provided herein serve as the first description of PEP-based biopotentiation of hydrogels implemented to restore skeletal muscle function and may serve as a promising approach for the nonsurgical management of SUI.

Cell-based therapy for the deficient urinary sphincter

When sterile culture techniques of mammalian cells first became state of the art, there was tremendous anticipation that such cells could be eventually applied for therapeutic purposes. The discovery of adult human stem or progenitor cells further motivated scientists to pursue research in cell-based therapies. Although evidence from animal studies suggests that application of cells yields measurable benefits, in urology and many other disciplines, progenitor-cell-based therapies are not yet routinely clinically available. Stress urinary incontinence (SUI) is a condition affecting a large number of patients. The etiology of SUI includes, but is not limited to, degeneration of the urinary sphincter muscle tissue and loss of innervation, as well as anatomical and biomechanical causes. Therefore, different regimens were developed to treat SUI. However, at present, a curative functional treatment is not at hand. A progenitor-cell-based therapy that can tackle the etiology of incontinence, rather than the consequences, is a promising strategy. Therefore, several research teams have intensified their efforts to develop such a therapy for incontinence. Here, we introduce candidate stem and progenitor cells suitable for SUI treatment, show how the functional homogeneity and state of maturity of differentiated cells crucial for proper tissue integration can be assessed electrophysiologically prior to their clinical application, and discuss the trophic potential of adult mesenchymal stromal (or stem) cells in regeneration of neuronal function.

Advances in Stem Cell Therapy for Erectile Dysfunction

Stem cell (SC) therapy for erectile dysfunction (ED) has been investigated in 35 published studies, with one being a small-scale clinical trial. Out of these 35 studies, 19 are concerned with cavernous nerve (CN) injury-associated ED while 10 with diabetes mellitus- (DM-) associated ED. Adipose-derived SCs (ADSCs) were employed in 18 studies while bone marrow SCs (BMSCs) in 9. Transplantation of SCs was done mostly by intracavernous (IC) injection, as seen in 25 studies. Allogeneic and xenogeneic transplantations have increasingly been performed but their immune-incompatibility issues were rarely discussed. More recent studies also tend to use combinatory therapies by modifying or supplementing SCs with angiogenic or neurotrophic genes or proteins. All studies reported better erectile function with SC transplantation, and the majority also reported improved muscle, endothelium, and/or nerve in the erectile tissue. However, differentiation or engraftment of transplanted SCs has rarely been observed; thus, paracrine action is generally believed to be responsible for SC’s therapeutic effects. But still, few studies actually investigated and none proved paracrine action as a therapeutic mechanism. Thus, based exclusively on functional outcome data shown in preclinical studies, two clinical trials are currently recruiting patients for treatment with IC injection of ADSC and BMSC, respectively.

The effect of urine-derived stem cells expressing VEGF loaded in collagen hydrogels on myogenesis and innervation following after subcutaneous implantation in nude mice

Impairment of sphincter muscles or their neural and vascular support leads to stress urinary incontinence. The aim of this study was to determine the role of urine-derived stem cells (USCs) over-expressing vascular endothelial growth factor (VEGF) in collagen-I gel on angiogenesis, cell survival, cell growth, myogenic phenotype differentiation of the implanted cells and innervations following implantation in vivo. USCs were infected with adenovirus containing the human VEGF165 and green fluorescent protein genes. A total of 5 × 10(6) cells, USCs alone, or plus endothelial cells or human skeletal myoblasts (as control) suspended in collagen-I gel were subcutaneously implanted into nude mice. Extensive vascularization and more implanted cells was noted in VEGF-expressing USCs groups compared to the non-VEGF groups in vivo. Numbers of the cells displaying endothelial markers (CD 31 and von Willebrand's factor) and myogenic markers (myf-5, MyoD and desmin), and regenerated nerve fibers displaying neural markers (S-100, GFAP and neurofilament) significantly increased in the grafts of VEGF-expressing USCs. Improved angiogenesis by VEGF-expressing USCs enhanced grafted cell survival, recruited the resident cells and promoted myogenic phenotype differentiation of USCs and innervation. This approach has important clinical implications for the development of cell therapies for the correction of stress urinary incontinence.

Isolation of muscle-derived stem/progenitor cells based on adhesion characteristics to collagen-coated surfaces

Our lab developed and optimized a method, known as the modified pre-plate technique, to isolate stem/progenitor cells from skeletal muscle. This method separates different populations of myogenic cells based on their propensity to adhere to a collagen I-coated surface. Based on their surface markers and stem-like properties, including self-renewal, multi-lineage differentiation, and ability to promote tissue regeneration, the last cell fraction or slowest to adhere to the collagen-coated surface (pre-plate 6; pp6) appears to be early, quiescent progenitor cells termed muscle-derived stem/progenitor cells (MDSPCs). The cell fractions preceding pp6 (pp1-5) are likely populations of more committed (differentiated) cells, including fibroblast- and myoblast-like cells. This technique may be used to isolate MDSPCs from skeletal muscle of humans or mice regardless of age, sex or disease state, although the yield of MDSPCs varies with age and health. MDSPCs can be used for regeneration of a variety of tissues including bone, articular cartilage, skeletal and cardiac muscle, and nerve. MDSPCs are currently being tested in clinical trials for treatment of urinary incontinence and myocardial infarction. MDSPCs from young mice have also been demonstrated to extend life span and healthspan in mouse models of accelerated aging through an apparent paracrine/endocrine mechanism. Here we detail methods for isolation and characterization of MDSPCs.

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.

Muscle-derived cells for treatment of iatrogenic sphincter damage and urinary incontinence in men

Introduction. Aim of this study was to assess the safety and efficacy of injection of autologous muscle-derived cells into the urinary sphincter for treatment of postprostatectomy urinary incontinence in men and to characterize the injected cells prior to transplantation. Methods. 222 male patients with stress urinary incontinence and sphincter damage after uroloical procedures were treated with transurethral injection of autologous muscle-derived cells. The transplanted cells were investigated after cultivation and prior to application by immunocytochemistry using different markers of myogenic differentiation. Feasibility and functionality assessment was achieved with a follow-up of at least 12 months. Results. Follow-up was at least 12 months. Of the 222 treated patients, 120 responded to therapy of whom 26 patients (12%) were continent, and 94 patients (42%) showed improvement. In 102 (46%) patients, the therapy was ineffective. Clinical improvement was observed on average 4.7 months after transplantation and continued in all improved patients. The cells injected into the sphincter were at least ~50% of myogenic origin and representative for early stages of muscle cell differentiation. Conclusions. Transurethral injection of muscle-derived cells into the damaged urethral sphincter of male patients is a safe procedure. Transplanted cells represent different phases of myogenic differentiation.

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.

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.

Bioactive porous beads as an injectable urethral bulking agent: in vivo animal study for the treatment of urinary incontinence

In our previous study, growth factor (basic fibroblast growth factor [bFGF] or vascular endothelial growth factor)-immobilized polycaprolactone (PCL)/Pluronic F127 porous beads were fabricated by an isolated particle-melting/melt-molding particulate-leaching method. The growth factors were easily immobilized onto the pore surfaces of the PCL/F127 beads via heparin binding, and were continuously released for up to 28 days. In this study, the growth factor-immobilized porous beads were investigated for their potential use as an injectable urethral bulking agent for the treatment of stress urinary incontinence (SUI). From the in vivo study using Sprague-Dawley rats as an urinary incontinent animal model, it was observed that the growth factor (bFGF or vascular endothelial growth factor)-immobilized porous beads had effective cure behaviors for SUI as follows: the narrowed urethral lumen and the regeneration of smooth muscle around the urethra. In particular, the bFGF-immobilized PCL/F127 porous beads showed desirable smooth muscle regeneration and electrical contractility, which indicates it can be a good candidate as an injectable bioactive bulking agent for the treatment of SUI.

[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.

A bilayered elastomeric scaffold for tissue engineering of small diameter vascular grafts

A major barrier to the development of a clinically useful small diameter tissue engineered vascular graft (TEVG) is the scaffold component. Scaffold requirements include matching the mechanical and structural properties with those of native vessels and optimizing the microenvironment to foster cell integration, adhesion and growth. We have developed a small diameter, bilayered, biodegradable, elastomeric scaffold based on a synthetic, biodegradable elastomer. The scaffold incorporates a highly porous inner layer, allowing cell integration and growth, and an external, fibrous reinforcing layer deposited by electrospinning. Scaffold morphology and mechanical properties were assessed, quantified and compared with those of native vessels. Scaffolds were then seeded with adult stem cells using a rotational vacuum seeding device to obtain a TEVG, cultured under dynamic conditions for 7 days and evaluated for cellularity. The scaffold showed firm integration of the two polymeric layers with no delamination. Mechanical properties were physiologically consistent, showing anisotropy, an elastic modulus (1.4 + or - 0.4 MPa) and an ultimate tensile stress (8.3 + or - 1.7 MPa) comparable with native vessels. The compliance and suture retention forces were 4.6 + or - 0.5 x 10(-4) mmHg(-1) and 3.4 + or - 0.3N, respectively. Seeding resulted in a rapid, uniform, bulk integration of cells, with a seeding efficiency of 92 + or - 1%. The scaffolds maintained a high level of cellular density throughout dynamic culture. This approach, combining artery-like mechanical properties and a rapid and efficient cellularization, might contribute to the future clinical translation of TEVGs.

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.

Implanted Mouse Bone Marrow-Derived Cells Reconstruct Layered Smooth Muscle Structures in Injured Urinary Bladders

This study is a preliminary investigation to determine if bone marrow-derived cells, when implanted into freeze-injured urinary bladders, differentiate into smooth muscle cells and reconstruct smooth muscle layers. Bone marrow cells were harvested from femurs of male ICR mice and cultured in collagen-coated dishes for 7 days. After 5 days of culture, the cells were transfected with green fluorescent protein (GFP) genes for identification in recipient tissues. Three days prior to implantation, the posterior urinary bladder walls of female nude mice were injured with an iron bar refrigerated by dry ice. Seven days after the culture and 3 days after the injury, adherent, proliferating GFP-labeled bone marrow-derived cells (1.0 × 105 cells) were implanted into the injured regions. For controls, a cell-free solution was injected. At 14 days after implantation, the experimental urinary bladders were analyzed by histological, gene expression, and cystometric investigations. Just prior to implantation, the injured regions did not have any smooth muscle layers. After 14 days, the implanted cells surviving in the recipient tissues were detected with GFP antibody. The implanted regions had distinct smooth muscle layers composed of regenerated smooth muscle marker-positive cells. The implanted GFP-labeled cells differentiated into smooth muscle cells that formed into layers. The differentiated cells contacted each other within the implanted region as well as smooth muscle cells of the host. As a result, the reconstructed smooth muscle layers were integrated into the host tissues. Control mice injected with cell-free solution developed only few smooth muscle cells and no layers. Cystometric investigations showed that mice with implanted the cells developed bladder contractions similar to normal mice, whereas control mice did not. In summary, mouse bone marrow-derived cells can reconstruct layered smooth muscle structures in injured bladders to remediate urinary dysfunction.

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.

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.

Development of a tissue-engineered vascular graft combining a biodegradable scaffold, muscle-derived stem cells and a rotational vacuum seeding technique

There is a clinical need for a tissue-engineered vascular graft (TEVG), and combining stem cells with biodegradable tubular scaffolds appears to be a promising approach. The goal of this study was to characterize the incorporation of muscle-derived stem cells (MDSCs) within tubular poly(ester urethane) urea (PEUU) scaffolds in vitro to understand their interaction, and to evaluate the mechanical properties of the constructs for vascular applications. Porous PEUU scaffolds were seeded with MDSCs using our recently described rotational vacuum seeding device, and cultured inside a spinner flask for 3 or 7 days. Cell viability, number, distribution and phenotype were assessed along with the suture retention strength and uniaxial mechanical behavior of the TEVGs. The seeding device allowed rapid even distribution of cells within the scaffolds. After 3 days, the constructs appeared completely populated with cells that were spread within the polymer. Cells underwent a population doubling of 2.1-fold, with a population doubling time of 35 h. Stem cell antigen-1 (Sca-1) expression by the cells remained high after 7 days in culture (77+/-20% vs. 66+/-6% at day 0) while CD34 expression was reduced (19+/-12% vs. 61+/-10% at day 0) and myosin heavy chain expression was scarce (not quantified). The estimated burst strength of the TEVG constructs was 2127+/-900 mm Hg and suture retention strength was 1.3+/-0.3N. We conclude from this study that MDSCs can be rapidly seeded within porous biodegradable tubular scaffolds while maintaining cell viability and high proliferation rates and without losing stem cell phenotype for up to 7 days of in-vitro culture. The successful integration of these steps is thought necessary to provide rapid availability of TEVGs, which is essential for clinical translation.

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.

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.

Myogenic precursor cells in craniofacial muscles

Craniofacial skeletal muscles (CskM), including the masticatory (MM), extraocular (EOM) and laryngeal muscles (LM), have a number of properties that set them apart from the majority of skeletal muscles (SkM). They have embryological origins that are distinct from musculature elsewhere in the body, they express a number of immature myosin heavy chain isoforms and maintain increased and distinct expression of a number of myogenic growth factors and their receptors from other adult SkMs. Furthermore, it has recently been demonstrated that unlike limb SkM, normal adult EOM and LM retain a population of activated satellite cells, the regenerative cell in adult SkM. In order to maintain this proliferative pool throughout life, CSkM may contain more satellite cells and/or more multipotent precursor cells that may be more resistant to apoptosis than those found in limb muscle. A further exciting question is whether this potentially more active muscle precursor cell population could be utilized not only for SkM repair, but be harnessed for repair or reconstruction of other tissues, such as nervous tissue or bone. This is a highly attractive speculation as the innate regenerative capacity of craniofacial muscles would ensure the donor tissue would not have compromised future function.

Stellenwert der Stammzelltherapie für die Behandlung der Belastungsinkontinenz

Parallel to a fundamental change in the therapeutic approach to managing stress incontinence, an increasing number of patients ask for reconstruction of the outer, striated urethral sphincter as therapy for urinary stress incontinence. Regenerative medicine is starting to offer solutions using stem cells as a part of oncological therapy or in reconstructive surgery. In addition to the many auspicious experimental approaches, one published study reports the effective therapeutic use of myogenic stem cells in urinary stress incontinent patients. Before this procedure is adopted into general clinical practice, further studies with validated evaluations and a sound legal basis are needed.

Sphincter incontinence: is regenerative medicine the best alternative to restore urinary or anal sphincter function?

Incontinence is a major public health concern in aging societies. It is caused by age-dependent spontaneous apoptosis of muscle cells in the urinary and fecal sphincters, and is aggravated in women due to birth trauma. Compared to other currently employed invasive surgical management techniques associated with morbidity and recurrence, replacement or regeneration of dysfunctional sphincter through stem cell therapy and tissue engineering techniques hold great promise. This review focuses on the pathophysiological analysis of urinary incontinence and the possible application of muscle-derived-stem cells, satellite cells, chondrocytes and adipose-derived-stem cells in restoring sphincter functions.

Muscling in on stem cells

Skeletal muscle is one of the few adult tissues that possesses the capacity for regeneration (restoration of lost functional tissue) as opposed to repair. This capacity is due to the presence of 'muscle stem cells' known as satellite cells. Detailed investigation of these cells over the past 50 years has revealed that both these and other cells within the skeletal muscle complex are capable of regenerating both muscle and other cell types as well. Here, we review this information, and suggest that skeletal muscle is an exciting reservoir of cells for regenerating skeletal muscle itself, as well as other cell types.

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.

Tissue engineering with muscle-derived stem cells

Tissue engineering and cell therapy approaches aim to take advantage of the repopulating ability and plasticity of multipotent stem cells to regenerate lost or diseased tissue. Researchers continue to investigate stem cells in mature tissues and demonstrate the potential ability of organ-specific cells to differentiate into multiple lineages. One stem cell that displays such promise is the muscle-derived stem cell (MDSC). Data supporting the existence of MDSCs have emerged as part of investigations to improve myoblast cell transplantation for the treatment of muscular dystrophies. As these efforts continue, the potential for MDSC-based therapy for other musculoskeletal injuries, as well as for cardiac and smooth muscle injuries, is currently being explored.

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.

Stammzelltherapie der Harninkontinenz

Experimental and clinical studies investigated whether urinary incontinence can be effectively treated with transurethral ultrasound-guided injections of autologous myoblasts and fibroblasts.This new therapy was performed in eight female pigs. It could be shown that the injected cells survived well and that new muscle tissue was formed. Next, 42 patients (29 women, 13 men) suffering from urinary stress incontinence were treated. The fibroblasts were mixed with a small amount of collagen as carrier material and injected into the urethral submucosa to treat atrophies of the mucosa. The myoblasts were directly injected into the rhabdosphincter to reconstruct the muscle and to heal morphological and functional defects. In 35 patients urinary incontinence could be completely cured. In seven patients who had undergone multiple surgical procedures and radiotherapy urinary incontinence improved. No side effects or complications were encountered postoperatively. The experimental as well as the clinical data clearly demonstrate that urinary incontinence can be treated effectively with autologous stem cells. The present data support the conclusion that this new therapeutic concept may represent a very promising treatment modality in the future.

Membrane properties of single muscle cells of the rhabdosphincter of the male urethra

BACKGROUND

The electrophysiological properties of myoblast cultures established from the human and porcine rhabdosphincter (RS) and porcine lower limb muscle (LLSKM) were studied to elucidate their potential for tissue engineering applications in the lower urinary tract.

METHODS

Muscle biopsies were collected from the prostatic part of the RS, the RS of male pigs, and the porcine LLSKM. Ion channels were studied by means of the patch-clamp technique.

RESULTS

Only one subtype each of voltage gated Na+ and Ca2+ channels was observed in porcine RS and LLSKM. Two types of voltage gated Ca2+ channels were identified in human RS cells. The porcine RS and LLSKM myoblasts displayed similar fusion competence.

CONCLUSIONS

Porcine RS and LLSKM myoblasts and human RS and human skeletal muscle cells show a high degree of similarity. Injection of autologous skeletal muscle myoboblasts in the lower urinary tract might, therefore, represent a promising approach to treat stress incontinence after radical prostatectomy.

Functional analysis of the tissue-engineered stomach wall

We have established a method for in situ tissue engineering of the stomach in a canine model using an acellular collagen scaffold graft. The current study was conducted to evaluate the functional aspects of the tissue-engineered stomach wall. The anterior wall of the stomach in beagle dogs was replaced with a collagen sponge scaffold measuring 4 x 4 cm. At 16 weeks after implantation, the animals were sacrificed and the stomach specimens were evaluated immunohistochemically and physiologically. Regeneration of the proton pump and thin muscle layer, which are essential for mechanical and chemical digestion by the stomach, was observed in the tissue-engineered gastric tissue. However, acetylcholine-induced contraction was not observed in the tissue-engineered stomach wall. Although there is still room for improvement, the tissue-engineered stomach wall had a highly organized structure, and it is anticipated that this approach could eventually become an alternative for stomach reconstruction after gastrectomy.