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

Developing a Cell-Microcarrier Tissue-Engineered Product for Muscle Repair Using a Bioreactor System

Fecal incontinence, although not life-threatening, has a high impact on the economy and patient quality of life. So far, available treatments are based on both surgical and nonsurgical approaches. These can range from changes in diet, to bowel training, or sacral nerve stimulation, but none of which provides a long-term solution. New regenerative medicine-based therapies are emerging, which aim at regenerating the sphincter muscle and restoring continence. Usually, these consist of the administration of a suspension of expanded skeletal-derived muscle cells (SkMDCs) to the damaged site. However, this strategy often results in a reduced cell viability due to the need for cell harvesting from the expansion platform, as well as the non-native use of a cell suspension to deliver the anchorage-dependent cells. In this study, we propose the proof-of-concept for the bioprocessing of a new cell delivery method for the treatment of fecal incontinence, obtained by a scalable two-step process. First, patient-isolated SkMDCs were expanded using planar static culture systems. Second, by using a single-use PBS-MINI Vertical-Wheel® bioreactor, the expanded SkMDCs were combined with biocompatible and biodegradable (i.e., directly implantable) poly(lactic-co-glycolic acid) microcarriers prepared by thermally induced phase separation. This process allowed for up to 80% efficiency of SkMDCs to attach to the microcarriers. Importantly, SkMDCs were viable during all the process and maintained their myogenic features (e.g., expression of the CD56 marker) after adhesion and culture on the microcarriers. When SkMDC-containing microcarriers were placed on a culture dish, cells were able to migrate from the microcarriers onto the culture surface and differentiate into multinucleated myotubes, which highlights their potential to regenerate the damaged sphincter muscle after administration into the patient. Overall, this study proposes an innovative method to attach SkMDCs to biodegradable microcarriers, which can provide a new treatment for fecal incontinence.

A bioactive injectable bulking material; a potential therapeutic approach for stress urinary incontinence

Stress urinary incontinence (SUI) is a life changing condition, affecting 20 million women worldwide. In this study, we developed a bioactive, injectable bulking agent that consists of Permacol™ (Medtronic, Switzerland) and recombinant insulin like growth factor-1 conjugated fibrin micro-beads (fib_rIGF-1) for its bulk stability and capacity to induce muscle regeneration. Therefore, Permacol™ formulations were injected in the submucosal space of rabbit bladders. The ability of a bulking material to form a stable and muscle-inducing bulk represents for us a promising therapeutic approach to achieve a long-lasting treatment for SUI. The fib_rIGF-1 showed no adverse effect on human smooth muscle cell metabolic activity and viability in vitro based on AlamarBlue assays and Live/Dead staining. Three months after injection of fib_rIGF-1 together with Permacol™ into the rabbit bladder wall, we observed a smooth muscle tissue like formation within the injected materials. Positive staining for alpha smooth muscle actin, calponin, and caldesmon demonstrated a contractile phenotype of the newly formed smooth muscle tissue. Moreover, the fib_rIGF-1 treated group also improved the neovascularization at the injection site, confirmed by CD31 positive staining compared to bulks made of Permacol^TM only. The results of this study encourage us to further develop this injectable, bioactive bulking material towards a future therapeutic approach for a minimal invasive and long-lasting treatment of SUI.

rHGF interacts with rIGF-1 to activate the satellite cells in the striated urethral sphincter in rats: a promising treatment for urinary incontinence?

Purpose

There are multitudes of factors contributing to urinary incontinence (UI). Dysfunction of the urethral sphincter is one of the common variables. Fortunately, satellite cells, which have the characteristics of stem cells, exist in the striated urethral sphincter. The purpose of the study was to seek whether rHGF combined with rIGF-1 owns the ability to promote the activation, proliferation, and differentiation of satellite cells to potentially improve urinary incontinence.

Methods

The SD rats were randomly divided into four groups and injected with 10 μl rIGF-1, the concentration of which was 50 μg/ml into the urethral wall of the urethral sphincter. Meanwhile, three groups were additionally treated with 10 μl rHGF, the concentration of which was 20, 50, 100 μg/ml. The group injected only with rIGF-1 was used as a control. 30 days later, the urethral tissues were harvested and serially sectioned. Immunofluorescent staining and HE staining were used to detect the activation, proliferation, and differentiation condition of satellite cells. The real-time RT-PCR analysis was applied to explore the potential signaling pathways.

Result

Anti-c-Met antibody-positive cells were discovered in the striated urethral sphincter. Positive expression of c-Met was relatively higher with the treatment of 100 μg/ml rHGF compared to other concentration of rHGF. A similar result was found in additional immunofluorescent staining. The number of newborn myofibers with central nuclei increased as the concentration of rHGF becoming higher. The mRNA expression of ERK1, ERK2 and AKT was comparatively higher with the injection of 50 μg/ml rHGF.

Conclusion

There is supposed to be a synergistic effect between rHGF and rIGF-1 to promote satellite cell to activate, proliferate and differentiate into muscle cells. The urethral sphincter may be induced to renew by the injection of rHGF and rIGF-1 into the urethral wall. It can be used to develop a new therapy for UI.

Functional and histologic effects after implanting pluripotent stem cells in a murine model with sphincterotomy

INTRODUCTION AND AIMS

Fecal incontinence is a disabling condition with devastating consequences for the patients. Medical and surgical options are not very satisfactory, reason by which regenerative medicine has been considered in this field. In the present research, we analyzed functional and histologic effects after implanting pluripotent stem cells (PSCs) in a murine model with sphincterotomy.

MATERIALS AND METHODS

Female Wistar rats were subjected to sphincterotomy and divided into three groups. Group 1 (control group) was treated with 300μL of balanced saline solution and group 2 (late treatment) and group 3 (early treatment) received 50,000 PSCs resuspended in 300μL of balanced saline solution. All animals were evaluated through high-resolution anorectal manometry 24hours before and after sphincterotomy and every month for three months. Finally, the rats were euthanized and histopathologic sections from the anal canal were obtained.

RESULTS

All groups showed a decrease in resting anal pressure and squeeze anal pressure 24hours after sphincterotomy. At the third month, higher anal pressures in the groups treated with PSCs were detected. Regarding the histologic effects, the microscopic architecture was restored and there was a significant decrease in the inflammatory response in the groups treated with PSCs.

CONCLUSION

PSCs implantation improves anal tone, as well as histologic structure, presenting better regenerative results when implanted as early treatment.

Microfluidic production of bioactive fibrin micro-beads embedded in crosslinked collagen used as an injectable bulking agent for urinary incontinence treatment

Endoscopic injection of bulking agents has been widely used to treat urinary incontinence, often due to urethral sphincter complex insufficiency. The aim of the study was to develop a novel injectable bioactive collagen-fibrin bulking agent restoring long-term continence by functional muscle tissue regeneration. Fibrin micro-beads were engineered using a droplet microfluidic system. They had an average diameter of 140 μm and recombinant fibrin-binding insulin-like growth factor-1 (α₂PI_1-8-MMP-IGF-1) was covalently conjugated to the beads. A plasmin fibrin degradation assay showed that 72.5% of the initial amount of α₂PI_1-8-MMP-IGF-1 loaded into the micro-beads was retained within the fibrin micro-beads. In vitro, the growth factor modified fibrin micro-beads enhanced cell attachment and the migration of human urinary tract smooth muscle cells, however, no change of the cellular metabolic activity was seen. These bioactive micro-beads were mixed with genipin-crosslinked homogenized collagen, acting as a carrier. The collagen concentration, the degree of crosslinking, and the mechanical behavior of this bioactive collagen-fibrin injectable were comparable to reference samples. This novel injectable showed no burst release of the growth factor, had a positive effect on cell behavior and may therefore induce smooth muscle regeneration in vivo, necessary for the functional treatment of stress and other urinary incontinences.

STATEMENT OF SIGNIFICANCE

Urinary incontinence is involuntary urine leakage, resulting from a deficient function of the sphincter muscle complex. Yet there is no functional cure for this devastating condition using current treatment options. Applied physical and surgical therapies have limited success. In this study, a novel bioactive injectable bulking agent, triggering new muscle regeneration at the injection site, has been evaluated. This injectable consists of cross-linked collagen and fibrin micro-beads, functionalized with bound insulin-like growth factor-1 (α₂PI_1-8-MMP-IGF-1). These bioactive fibrin micro-beads induced human smooth muscle cell migration in vitro. Thus, this injectable bulking agent is apt to be a good candidate for regeneration of urethral sphincter muscle, ensuring a long-lasting treatment for urinary incontinence.

Functional Outcome of Human Adipose Stem Cell Injections in Rat Anal Sphincter Acute Injury Model

Anal incontinence is a devastating condition that significantly reduces the quality of life. Our aim was to evaluate the effect of human adipose stem cell (hASC) injections in a rat model for anal sphincter injury, which is the main cause of anal incontinence in humans. Furthermore, we tested if the efficacy of hASCs could be improved by combining them with polyacrylamide hydrogel carrier, Bulkamid. Human ASCs derived from a female donor were culture expanded in DMEM/F12 supplemented with human platelet lysate. Female virgin Sprague‐Dawley rats were randomized into four groups (n = 14–15/group): hASCs in saline or Bulkamid (3 × 10⁵/60 μl) and saline or Bulkamid without cells. Anorectal manometry (ARM) was performed before anal sphincter injury, at two (n = 58) and at four weeks after (n = 33). Additionally, the anal sphincter tissue was examined by micro‐computed tomography (μCT) and the histological parameters were compared between the groups. The median resting and peak pressure during spontaneous contraction measured by ARM were significantly higher in hASC treatment groups compared with the control groups without hASCs. There was no statistical difference in functional results between the hASC‐carrier groups (saline vs. Bulkamid). No difference was detected in the sphincter muscle continuation between the groups in the histology and μCT analysis. More inflammation was discovered in the group receiving saline with hASC. The hASC injection therapy with both saline and Bulkamid is a promising nonsurgical treatment for acute anal sphincter injury. Traditional histology combined with the 3D μCT image data lends greater confidence in assessing muscle healing and continuity. Stem Cells Translational Medicine2018;7:295–304

Artificial Muscle Devices: Innovations and Prospects for Fecal Incontinence Treatment

Fecal incontinence describes the involuntary loss of bowel content, which is responsible for stigmatization and social exclusion. It affects about 45% of retirement home residents and overall more than 12% of the adult population. Severe fecal incontinence can be treated by the implantation of an artificial sphincter. Currently available implants, however, are not part of everyday surgery due to long-term re-operation rates of 95% and definitive explantation rates of 40%. Such figures suggest that the implants fail to reproduce the capabilities of the natural sphincter. This article reviews the artificial sphincters on the market and under development, presents their physical principles of operation and critically analyzes their performance. We highlight the geometrical and mechanical parameters crucial for the design of an artificial fecal sphincter and propose more advanced mechanisms of action for a biomimetic device with sensory feedback. Dielectric electro-active polymer actuators are especially attractive because of their versatility, response time, reaction forces, and energy consumption. The availability of such technology will enable fast pressure adaption comparable to the natural feedback mechanism, so that tissue atrophy and erosion can be avoided while maintaining continence during daily activities.

Tissue-Engineered External Anal Sphincter Using Autologous Myogenic Satellite Cells and Extracellular Matrix: Functional and Histological Studies

The aim of the present study was to demonstrate the regaining histological characteristics of bioengineered external anal sphincters (EAS) in rabbit fecal incontinence model. The EAS of 16 rabbits were resected and decellularized. The decellularized scaffolds were transplanted to the terminal rectum following a period of 6 months of fecal incontinency (5 days after sterilization). The rabbits were divided into two groups: in group 1 (n = 8), myogenic satellite cells were injected into the transplanted sphincters. In group 2 (n = 8), the transplanted scaffolds remained in situ without cellular injection. The histological evaluation was performed with desmin, myosin, smooth muscle actin, CD31, and CD34 at 3-month intervals. The rabbits were followed for 2 years. Electromyography (EMG) with needle and electrical stimulation, pudendal and muscle electrical stimulation were also performed after 2 years of transplantation. At the time of biopsy, no evidence of inflammation or rejection was observed and the transplanted EAS appeared histologically and anatomically normal. The immunohistochemistry staining validated that the histological features of EAS was more satisfactory in group 1 in short-term follow-up. However, no statistically significant difference was detected between two groups in long-term follow-ups (p value > 0.05). In both groups, grafted EAS contracted in response to electrical signals delivered to the muscle and the pudendal nerve. However, more signals were detected in group 1 in EMG evaluation. In conclusion, bioengineered EAS with myogenic satellite cells can gain more satisfactory histological outcomes in short-term follow-ups with better muscle electrical stimulation outcomes.

Dual growth factor-immobilized microspheres for tissue reinnervation: in vitro and preliminary in vivo studies

Growth factors (GFs) (basic fibroblast growth factor (bFGF) and/or nerve growth factor (NGF))-immobilized polycaprolactone (PCL)/Pluronic F127 microspheres were prepared using an isolated particulate-melting method and the sequential binding of heparin and GFs onto the microspheres. The GFs immobilized on the microspheres were released in a sustained manner over 28 days, regardless of GF type. From the in vitro culture of muscle-derived stem cells, it was observed that the NGF-immobilized microspheres induced more neurogenic differentiation than the bFGF-immobilized microspheres, as evidenced by a quantitative real-time polymerase chain reaction using specific neurogenic markers (Nestin, GFAP, β-tubulin, and MAP2) and Western blot (Nestin and β-tubulin) analyses. The dual bFGF/NGF-immobilized microspheres showed better neurogenic differentiation than the microspheres immobilized with single bFGF or NGF. From the preliminary animal study, the dual bFGF/NGF-immobilized microsphere group also showed effective nerve regeneration, as evaluated by immunocytochemistry using a marker - β-tubulin. The dual bFGF/NGF-immobilized PCL/Pluronic F127 microspheres may be a promising candidate for nerve regeneration in certain target tissues (i.e. muscles) leading to sufficient reinnervation.

Dual growth factor-loaded in situ gel-forming bulking agent: passive and bioactive effects for the treatment of urinary incontinence

Stress urinary incontinence (SUI) is one of the major medical problems for adult females and has a devastating effect on their quality of life. The major cause of the development of the SUI is dysfunction of the urethral supporting tissues as a result of aging and childbirth. In this study, in situ gel-forming bulking agent loaded with dual growth factors, nerve growth factor (NGF) and basic fibroblast growth factor (bFGF), was fabricated. The bulking agent consisted of three components; (i) polycaprolactone (PCL) beads, (ii) bFGF-loaded nanogels, and (iii) NGF-loaded in situ gel forming solution. The bulking agent can provide an initial passive bulking effect (from the PCL beads) and regenerate malfunctioning tissues around the urethra (from the sequential and continuous release of growth factors from the hydrogel) for the effective treatment of SUI. The PCL beads were located stably at the applied urethra site (urinary incontinent SD rat) without migration to provide a passive bulking effect. The sequential release of the growth factors (NGF within a week and bFGF for more than 4 weeks) from the bulking agent provided regeneration of damaged nerve and smooth muscle, and thus enhanced biological function around the urethra. From the findings, we suggest that dual growth factor (NGF and bFGF)-loaded in situ gel-forming bulking agent may be a promising injectable bioactive system for the treatment for SUI.

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

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

A novel animal model of long-term sustainable anal sphincter dysfunction

BACKGROUND

Although intersphincteric resection can avoid the need for permanent colostomy in patients with lower rectal cancer, it sometimes causes anal sphincter dysfunction, thus resulting in a lifelong, debilitating disorder due to incontinence of solid and liquid stool. The development of regenerative medicine could improve this condition by regenerating impaired anal muscle. In order to prove this hypothesis, preliminary experiments in animals will be indispensable; however, an adequate animal model is currently lacking. The purpose of this study was to establish a novel animal model with long-term sustainable anal sphincter dysfunction.

MATERIALS AND METHODS

Twenty male Sprague-Dawley rats were allocated into sham operation (n = 10) and anal sphincter resection (ASR) (n = 10) groups. The ASR group underwent removal of the left half of both the internal and external anal sphincters. Both groups were evaluated for anal function by measuring their resting pressure before surgery and on postoperative day (POD) 1, 7, 14, and 28.

RESULTS

The rats in the sham operation group recovered their anal pressure up to baseline on POD 7. The rats in the ASR group showed a significant decrease in anal pressure on POD 1 (P < 0.0001) compared with the baseline, and kept this low pressure until POD 28 (P < 0.0001). The defect of the anal sphincter muscle was confirmed histologically in the ASR group on POD 28.

CONCLUSIONS

The present novel model exhibits continuous anal sphincter dysfunction for at least 1 mo and may contribute to further studies evaluating the efficacy of therapies such as regenerative medicine.

Functional recovery of urethra by plasmid DNA-loaded injectable agent for the treatment of urinary incontinence

Stress urinary incontinence (SUI) is an embarrassing problem affecting a large number of women and interfering with their quality of life. The injury or weakness of urethral supporting tissues by childbirth and aging has been considered as key factors in the development of the SUI. In this study, plasmid DNA (pDNA; encoding for bFGF) complex-loaded poly(DL-lactic-co-glycolic acid) (PLGA)/Pluronic F127 mixture dispersed with polycaprolactone (PCL) microspheres was prepared as an injectable bioactive bulking agent that may provide bulking effect (by PCL microspheres) and allow stimulation of the defect tissues around urethra (by synthesis of bFGF from cells or tissues transfected by the pDNA complex) for the effective treatment of SUI. From in vitro experiments, the pDNA complex incorporated in the bulking agent was released in a sustained manner over 84 days (≥80% of the initial loading amount). The pDNA complex was effectively transfected into fibroblasts and the cells were continuously producing the target protein, bFGF. From the in vivo study using hairless mice and Sprague-Dawley rats, it was confirmed that the pDNA complex released from the bulking agent is transfected into surrounding cells/tissue, and the cells/tissues synthesize sufficient bFGF to regenerate smooth muscle with biological function around the urethra. Basis on these results, the pDNA (encoding for bFGF) complex-loaded PLGA/Pluronic F127 mixture dispersed with PCL microspheres can be a promising bioactive bulking agent system for the fundamental cure of SUI.

Stem cells in gynecology

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

Allogenic myoblast transplantation in the rat anal sphincter

OBJECTIVES

: To determine the feasibility of injecting rat myoblasts into the intact anal sphincter as a potential treatment for anal incontinence, and to detect transferred myoblast survival and integration.

STUDY DESIGN

: A pilot study using nonpregnant female Sprague Dawley rodents of 8 to 10 weeks of age. A biopsy of skeletal muscle was harvested from a study animal and recovered myoblasts were expanded in vitro over 10 days. Myoblasts were then tagged with a cytomegalovirus promoter to transduce green fluorescent protein (GFP) into the myoblasts. The cell aspirate was injected directly into the intact external anal sphincter using an electromyographic guidance. The animals received 1.5 or 4.5 × 10 cells of GFP-labeled myoblasts, dividing the dose between three injection sites. The remaining in vitro myoblasts were still viable 28 days post-harvest. Ten days after transplantation the anal sphincter complex was surgically extracted.

RESULTS

: The presence of GFP-labeled myoblasts was confirmed within the external anal sphincter.

CONCLUSIONS

: This demonstrates that myoblasts can be successfully extracted, cultivated in vitro, transplanted and will integrate into the host tissue.

Low current electrical stimulation upregulates cytokine expression in the anal sphincter

AIM

Stem cells are an emerging treatment for regeneration of damaged anal sphincter tissues. Homing to the site of injury can be potentiated by stromal derived factor 1 (SDF-1) and monocyte chemotactic protein 3 (MCP-3) expression. The effects of electrical stimulation (ES) on upregulation of these cytokines were investigated.

METHODS

The anal sphincter complex of Sprague Dawley rats was stimulated with current of 0.25 mA, pulse duration of 40 pulses/s, pulse width of 100 μs, and frequency of 100 Hz for 1 or 4 h. Sham was created using the same needle which was inserted into the anal sphincter without electrical stimulation in different groups of animals. The rats were euthanized immediately or 24 h after stimulation. Cytokine analysis was performed using real-time polymerase chain reaction. Statistical analysis was performed.

RESULTS

Results are presented as a fold increase compared to sham that was normalized to 1. SDF-1 and MCP-3 immediately after 1 h were 2.5 ± 0.77 and 3.1± 0.93 vs. sham, respectively, showing significant increase. After 1-h stimulation and euthanasia 24 h after, SDF-1 and MCP-3 were 1.49 ± 0.16 and 1.51± 0.14 vs. sham, respectively, showing significant increase. Immediately and 24 h after 4-h stimulation, SDF-1 was 1.21 ± 0.16 and 0.54 ± 0.16 vs. sham, respectively, and was not significantly different. Immediately and 24 h after 4-h stimulation, MCP-3 was 1.29 ± 0.41 and 0.35 ±1.0 vs. sham, respectively, and was not significantly different. SDF-1 and MCP-3 after 1 h were significantly higher than after 4 h of stimulation at both time points.

CONCLUSION

Electrical stimulation for 1 h significantly upregulates SDF-1 and MCP-3 expression that persists for 24 h. Prolonged stimulation reduced chemokine expression, suggesting electrolysis of cells.

Polymeric implant materials for the reconstruction of tracheal and pharyngeal mucosal defects in head and neck surgery

The existing therapeutical options for the tracheal and pharyngeal reconstruction by use of implant materials are described. Inspite of a multitude of options and the availability of very different materials none of these methods applied for tracheal reconstruction were successfully introduced into the clinical routine. Essential problems are insufficiencies of anastomoses, stenoses, lack of mucociliary clearance and vascularisation. The advances in Tissue Engineering (TE) offer new therapeutical options also in the field of the reconstructive surgery of the trachea. In pharyngeal reconstruction far reaching developments cannot be recognized at the moment which would allow to give a prognosis of their success in clinical application. A new polymeric implant material consisting of multiblock copolymers was applied in our own work which was regarded as a promising material for the reconstruction of the upper aerodigestive tract (ADT) due to its physicochemical characteristics. In order to test this material for applications in the ADT under extreme chemical, enzymatical, bacterial and mechanical conditions we applied it for the reconstruction of a complete defect of the gastric wall in an animal model. In none of the animals tested either gastrointestinal complications or negative systemic events occurred, however, there was a multilayered regeneration of the gastric wall implying a regular structured mucosa.

In future the advanced stem cell technology will allow further progress in the reconstruction of different kind of tissues also in the field of head and neck surgery following the principles of Tissue Engineering.

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.

Bioactive porous beads as an injectable urethral bulking agent: their in vitro evaluation on smooth muscle cell differentiation

Growth factor (basic fibroblast growth factor or vascular endothelial growth factor)-immobilized polycaprolactone (PCL)/Pluronic F127 porous beads were prepared as an injectable bulking agent for effective treatment of urinary incontinence. The growth factor-immobilized porous beads may stimulate smooth muscle cell (SMC) differentiation of muscle-derived stem cells or defect tissues around urethra to improve the sphincter function (bioactive therapy) as well as to provide a bulking effect (passive therapy). The porous PCL/F127 beads were fabricated by an isolated particle-melting/melt-molding particulate-leaching method. The growth factors were easily immobilized onto the surfaces of the PCL/F127 porous beads via heparin binding and were continuously released for up to 28 days. Both growth factor-immobilized porous beads had a positive effect for the SMC differentiation of muscle-derived stem cells, as were demonstrated by the analyses of quantitative polymerase chain reactions, Western blot using SMC-specific markers, and immunohistochemical staining. In particular, the basic fibroblast growth factor-immobilized porous beads showed desirable SMC differentiation behavior that can be applied as an injectable bulking agent for the treatment of urinary incontinence.

Human umbilical cord blood mononuclear cell transplantation in rats with intrinsic sphincter deficiency

To evaluate the effectiveness of the human umbilical cord blood (HUCB) transplantation for the treatment of intrinsic sphincter deficiency (ISD), we analyzed the short term effects of HUCB mononuclear cell transplantation in rats with induced-ISD. ISD was induced in rats by electro-cauterization of periurethral soft tissue with HUCB mononuclear cell injection after 1 week. The sphincter function measured by mean leak point pressure was significantly improved in the experimental group compared to the control group at 4 weeks. (91.75+/-18.99 mmHg vs. 65.02+/-22.09 mmHg, P=0.001). Histologically, the sphincter muscle was restored without damage while in the control group it appeared markedly disrupted with atrophic muscle layers and collagen deposit. We identified injected HUCB cells in the tissue sections by Di-I signal and Prussian blue staining. HUCB mononuclear cell injection significantly improved urethral sphincter function, suggesting its potential efficacy in the treatment of ISD.

Cell-based therapy for urinary incontinence

Urinary incontinence has become a societal problem that affects millions of people worldwide. Although numerous therapeutic modalities are available, none has been shown to be entirely satisfactory. Consequently, cell-based approaches using regenerative medicine technology have emerged as a potential solution that would provide a means of correcting anatomical deficiencies and restoring normal function. As such, numerous cell-based investigations have been performed to develop systems that are focused on addressing clinical needs. While most of these attempts remain in the experimental stages, several clinical trials are being designed or are in progress. This article provides an overview of the cell-based approaches that utilize various cell sources to develop effective treatment modalities for urinary incontinence.

Endoscopic injection of skeletal muscle-derived cells augments gut smooth muscle sphincter function: implications for a novel therapeutic approach

INTRODUCTION

Sphincter function is a common problem in gastroenterology and leads to disorders such as GERD and fecal incontinence.

OBJECTIVE

We hypothesized that transplantation of skeletal muscle-derived cells (MDCs) into GI sphincters may improve their function, leading to a more physiological approach to treating these disorders.

DESIGN

We performed experiments to test the potential of MDCs to survive and differentiate within the GI smooth muscle in order to gain further knowledge on the biology of skeletal muscle transplantation in GI smooth muscle sphincters as well as to test the safety and feasibility of endoscopic injection of MDCs in a large animal model.

SETTING

Animal laboratory.

INTERVENTIONS

Adult male Sprague-Dawley rats and adult male beagle dogs were used. Rat-derived and dog-derived MDCs were prepared in vitro and labeled with DiI. DiI-labeled, rat-derived MDCs (200,000/4 muL phosphate buffered saline solution) were injected bilaterally in the pyloric wall of rats, and survival, differentiation, and in vitro contractility were assessed 1 month after transplantation. Dog-derived MDCs (4.0 x 10(6) cells) were also injected into the lower esophageal sphincter of 3 beagle dogs by using a standard variceal sclerotherapy needle after baseline esophageal manometry and pH monitoring. The dogs were treated with daily cyclosporine, and 2 weeks later esophageal manometry was repeated and the esophagus was examined histologically. Differentiation of grafted cells was assessed by immunofluorescence, using specific antibodies to markers of the smooth muscle phenotype (smooth muscle actin) and of the skeletal muscle phenotype (skeletal muscle myosin).

RESULTS

In rats, grafted MDCs were visualized based on DiI fluorescence and were found to be localized within the muscle wall and in the muscularis mucosa. In vitro organ bath studies showed a significant increase in the contractile response of the pyloric sphincter to exogenous acetylcholine. In dogs, MDC injection resulted in a significant increase in baseline lower esophageal sphincter pressure. Further, in 1 dog with significant baseline acid reflux, MDC injection resulted in a reduction of acid reflux, with the fraction of time with pH <4 decreasing from 26.5% to 1.5%. Transplanted MDCs were seen adding bulk to the lower esophageal area and were well-integrated into the surrounding tissue. Immunofluorescence analysis revealed weak expression of skeletal muscle myosin in grafted MDCs and no expression of smooth muscle actin in either rats or dogs.

LIMITATIONS

Animal study.

CONCLUSION

MDCs can survive and integrate into GI smooth muscle and augment their contractile response. Thus, they may have potential for the treatment of a variety of conditions.

Potential of human umbilical cord matrix and rabbit bone marrow-derived mesenchymal stem cells in repair of surgically incised rabbit external anal sphincter

PURPOSE

Anal sphincter defects and fecal incontinence are complicated surgical problems. We investigated the ability of human umbilical cord matrix (hUCM) and rabbit bone marrow (rBM) stem cells to improve anal sphincter incontinence due to induced sphincter defects without surgical repair.

METHODS

We harvested hUCM cells from human Wharton's jelly and rBM stem cells from rabbit femurs and tibias. To induce sphincter defects, we made an incision in the external anal sphincter. Rabbits were randomly allocated to 5 groups to receive either no intervention (n = 3) or injections of 10 hUCM cells in medium (10 microL RPMI-1640), rBM cells in medium, medium only, or normal saline (n = 7 per group), 2 weeks after sphincterotomy. Transplanted cells were tracked in the injured sphincters by prelabeling with bromodeoxyuridine. Electromyography was performed before and 2 weeks after the external anal sphincterotomy, and 2 weeks after cell transplantation. We also evaluated the proliferation and differentiation of injected cells with histopathologic techniques.

RESULTS

Electromyography showed significant improvement in sphincter function 2 weeks after local injection of rBM stem cells compared with pretreatment values and controls. Moderate, nonsignificant improvement was observed with hUCM cell injection. Cells with incorporated bromodeoxyuridine were detected at the site of injury after transplantation of hUCM and rBM. Histopathologic evaluation showed normal or muscle-dominant sphincter structure in all animals receiving rBM and fibrous-dominant sphincter structure in most animals receiving hUCM.

CONCLUSIONS

Stem cell injection at the site of injury can enhance contractile function of the anal sphincter without surgical repair. Transplantation of stem cells, particularly bone marrow mesenchymal cells, may provide an effective tool for treating anal sphincter injuries in humans.

Regenerative Medicine: Applications and Development in Urology

Purpose

Congenital abnormalities and acquired disorders can lead to organ damage and loss. Nowadays, transplantation represents the only effective treatment option. However, there is a marked decrease in the number of organ donors, which is even yearly worsening due to the population aging. The regenerative medicine represents a realistic option that allows to restore and maintain the normal functions of tissues and organs. This article reviews the principles of regenerative medicine and the recent advances with regard to its application to the genitourinary tract.

Recent findings

The field of regenerative medicine involves different areas of technology, such as tissue engineering, stem cells and cloning. Tissue engineering involves the field of cell transplantation, materials science and engineering in order to create functional replacement tissues. Stem cells and cloning permit the extraction of pluripotent, embryonic stem cells offering a potentially limitless source of cells for tissue engineering applications. Most current strategies for tissue engineering depend upon a sample of autologous cells from the patient's diseased organ. Biopsies from patients with extensive end-stage organ failure, however, may not yield enough normal cells. In these situations, stem cells are envisaged as being an alternative source. Stem cells can be derived from discarded human embryos (human embryonic stem cells), from fetal tissue or from adult sources (bone marrow, fat, skin). Therapeutic cloning offers a potentially limitless source of cells for tissue engineering applications. Regenerative medicine and tissue engineering scientists have increasingly applied the principles of cell transplantation, materials science and bioengineering to construct biological substitutes that will restore and maintain normal function in urological diseased and injured tissues such as kidney, ureter, bladder, urethra and penis.

Conclusions

Regenerative medicine offers several applications in acquired and congenital genitourinary diseases. Tissue engineering, stem cells and, mostly, cloning have been applied in experimental studies with excellent results. Few preliminary human applications have been developed with promising results.