Iltamiocel Autologous Cell Therapy for the Treatment of Female Stress Urinary Incontinence: A Double-Blind, Randomized, Stratified, Placebo-Controlled Trial.

AIMS: This study aimed to determine the efficacy and safety of iltamiocel investigational autologous muscle cell therapy in females with stress urinary incontinence (SUI). METHODS: Adult females were randomized 2:1 to iltamiocel (150 × 106 cells) or placebo and stratified by severity and prior SUI surgery. The primary objective was efficacy based on the frequency of stress incontinence episodes (SIE) recorded in a 3-day diary at 12 months posttreatment. After 12 months, placebo participants could elect to receive open-label iltamiocel. Efficacy and safety analyses were performed using all patients as treated populations. RESULTS: The study enrolled 311 patients, 297 were randomized to either iltamiocel (n = 199) or placebo (n = 98). Of the 295 participants that completed 12 months blinded follow-up, the proportion achieving the primary endpoint of ≥ 50% SIE reduction was not statistically different between treatment groups (52% vs. 53.6%; p = 0.798). A significantly greater proportion of iltamiocel participants in the prior SUI surgery stratum group achieved ≥ 75% SIE reduction compared with placebo, (40% vs. 16%; p = 0.037). Treatment response was maintained at 24 months in 78.4% and 64.9% of iltamiocel participants who achieved ≥ 50% and ≥ 75% SIE reduction, respectively, at Month 12. Adverse events related to the treatment were reported in 19 (9.5%) iltamiocel participants and 6 (6.1%) placebo participants. CONCLUSION: The study did not meet its primary endpoint however, iltamiocel cell therapy is safe and may be ideally suited to female patients who have undergone prior surgery for SUI. Additional study in this group of patients with high unmet medical needs is warranted. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01893138; EudraCT number: 2014-002919-41.

Safety and Efficacy of Iltamiocel Cellular Therapy for the Treatment of Fecal Incontinence. Results of a Phase 1/2 Study.

OBJECTIVE: To examine the safety and efficacy of iltamiocel, an investigational cellular therapy of autologous muscle-derived cells, as a treatment for fecal incontinence (FI) in adults. BACKGROUND: Limited therapeutic options are available for patients with FI refractory to conservative treatments. Cell therapy using autologous muscle-derived cells represents a promising, minimally invasive approach for restoring anal sphincter function. METHODS: In this multicenter, prospective, non-randomized study, 48 participants were treated with a single iltamiocel dose of 250×10 6 cells. The primary outcome was the incidence of product or procedure-related adverse events (AEs) and serious AEs. Secondary outcomes were changes in the number of FI episodes, Cleveland Clinic Incontinence Score, Fecal Incontinence Quality of Life, and anorectal manometry at 3, 6, and 12 months compared to baseline. RESULTS: No serious AEs and only one product-related AE of inflammation at the injection site were reported. At 12 months, there was a reduction in median FI episodes (-6.0; 95% confidence interval (CI): -10.0, -1.0) and days with episodes (-4.0; 95% CI: -8.0, -1.0). A ≥50% reduction in FI episodes was observed in 53.7% of participants, and 24.4% had complete restoration of continence. Symptom severity and quality of life improved with mean Cleveland Clinic Incontinence Score reduction (-2.9; 95% CI: -3.7, -2.1), and Fecal Incontinence Quality of Life increased (2.2; 95% CI:1.4, 2.9). No significant changes were detected in anorectal manometry measurements. A history of episiotomy was significantly associated with treatment response in multivariate analysis. CONCLUSION: The administration of iltamiocel cellular therapy is safe. Iltamiocel shows promise for significantly improving fecal incontinence symptoms and quality of life.

Barriers and Strategies to Operationalize Medicaid Reimbursement for CHW Services in the State of Minnesota: a Case Study.

Integrated medical and social care via community health worker (CHW) services is a growing area of interest, particularly among health care organizations that offer care for underserved populations. Establishing Medicaid reimbursement for CHW services is only one step to improve access to CHW services. Minnesota is one of 21 states that authorize Medicaid payment for CHW services. Despite available Medicaid reimbursement for CHW services since 2007, the actual experience of many Minnesota health care organizations in obtaining reimbursement for CHW services has been challenging due to barriers at multiple levels (e.g., clarifying and operationalizing regulation, navigating complexity of billing, building organizational capacity to reach key stakeholders at state agencies and health plans). This paper provides an overview of the barriers and strategies to operationalize Medicaid reimbursement for CHW services in the state of Minnesota, through the experience of a CHW service and technical assistance provider. Based on lessons learned in Minnesota, recommendations are made to other states, payers, and organizations as they navigate processes to operationalize Medicaid payment for CHW services.

Human skeletal muscle cells with a slow adhesion rate after isolation and an enhanced stress resistance improve function of ischemic hearts.

Identification of cells that are endowed with maximum potency could be critical for the clinical success of cell-based therapies. We investigated whether cells with an enhanced efficacy for cardiac cell therapy could be enriched from adult human skeletal muscle on the basis of their adhesion properties to tissue culture flasks following tissue dissociation. Cells that adhered slowly displayed greater myogenic purity and more readily differentiated into myotubes in vitro than rapidly adhering cells (RACs). The slowly adhering cell (SAC) population also survived better than the RAC population in kinetic in vitro assays that simulate conditions of oxidative and inflammatory stress. When evaluated for the treatment of a myocardial infarction (MI), intramyocardial injection of the SACs more effectively improved echocardiographic indexes of left ventricular (LV) remodeling and contractility than the transplantation of the RACs. Immunohistological analysis revealed that hearts injected with SACs displayed a reduction in myocardial fibrosis and an increase in infarct vascularization, donor cell proliferation, and endogenous cardiomyocyte survival and proliferation in comparison with the RAC-treated hearts. In conclusion, these results suggest that adult human skeletal muscle-derived cells are inherently heterogeneous with regard to their efficacy for enhancing cardiac function after cardiac implantation, with SACs outperforming RACs.

Autologous Muscle-Derived Cell Therapy for Swallowing Impairment in Patients Following Treatment for Head and Neck Cancer.

OBJECTIVES/HYPOTHESIS: To evaluate the safety and potential efficacy of autologous muscle-derived cells (AMDCs) for the treatment of swallowing impairment following treatment for oropharynx cancer. STUDY DESIGN: Prospective, phase I, open label, clinical trial. METHODS: Oropharynx cancer survivors disease free ≥2 years post chemoradiation were recruited. All patients had swallowing impairment but were not feeding tube dependent (Functional Oral Intake Scale [FOIS] ≥ 5). Muscle tissue (50-250 mg) was harvested from the vastus lateralis and 150 × 106 AMDCs were prepared (Cook MyoSite Inc., Pittsburgh, PA). The cells were injected into four sites throughout the intrinsic tongue musculature. Participants were followed for 24 months. The primary outcome measure was safety. Secondary endpoints included objective measures on swallowing fluoroscopy, oral and pharyngeal pressure, and changes in patient-reported outcomes. RESULTS: Ten individuals were enrolled. 100% (10/10) were male. The mean age of the cohort was 65 (±8.87) years. No serious adverse event occurred. Mean tongue pressure increased significantly from 26.3 (±11.1) to 31.8 (±9.5) kPa (P = .017). The mean penetration-aspiration scale did not significantly change from 5.6 (±2.1) to 6.8 (±1.8), and the mean FOIS did not significantly change from 5.4 (±0.5) to 4.6 (±0.7). The incidence of pneumonia was 30% (3/10) and only 10% (1/10) experienced deterioration in swallowing function throughout 2 years of follow-up. The mean eating assessment tool (EAT-10) did not significantly change from 24.1 (±5.57) to 21.3 (±6.3) (P = .12). CONCLUSION: Results of this phase I clinical trial demonstrate that injection of 150 × 106 AMDCs into the tongue is safe and may improve tongue strength, which is durable at 2 years. A blinded placebo-controlled trial is warranted. LEVEL OF EVIDENCE: 3 Laryngoscope, 132:523-527, 2022.

Muscle stem cells differentiate into haematopoietic lineages but retain myogenic potential.

Muscle-derived stem cells (MDSCs) can differentiate into multiple lineages, including haematopoietic lineages. However, it is unknown whether MDSCs preserve their myogenic potential after differentiation into other lineages. To address this issue, we isolated from dystrophic muscle a population of MDSCs that express stem-cell markers and can differentiate into various lineages. After systemic delivery of three MDSC clones into lethally irradiated mice, we found that differentiation of the donor cells into various lineages of the haematopoietic system resulted in repopulation of the recipients' bone marrow. Donor-derived bone-marrow cells, isolated from these recipients by fluorescence-activated cell sorting (FACS), also repopulated the bone marrow of secondary, lethally irradiated, recipients and differentiated into myogenic cells both in vitro and in vivo in normal mdx mice. These findings demonstrate that MDSC clones retain their myogenic potential after haematopoietic differentiation.

Identification of a novel population of muscle stem cells in mice: potential for muscle regeneration.

Three populations of myogenic cells were isolated from normal mouse skeletal muscle based on their adhesion characteristics and proliferation behaviors. Although two of these populations displayed satellite cell characteristics, a third population of long-time proliferating cells expressing hematopoietic stem cell markers was also identified. This third population comprises cells that retain their phenotype for more than 30 passages with normal karyotype and can differentiate into muscle, neural, and endothelial lineages both in vitro and in vivo. In contrast to the other two populations of myogenic cells, the transplantation of the long-time proliferating cells improved the efficiency of muscle regeneration and dystrophin delivery to dystrophic muscle. The long-time proliferating cells' ability to proliferate in vivo for an extended period of time, combined with their strong capacity for self-renewal, their multipotent differentiation, and their immune-privileged behavior, reveals, at least in part, the basis for the improvement of cell transplantation. Our results suggest that this novel population of muscle-derived stem cells will significantly improve muscle cell-mediated therapies.

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.

A double-blind, randomized, placebo-controlled clinical trial evaluating the safety and efficacy of autologous muscle derived cells in female subjects with stress urinary incontinence.

PURPOSE: The purpose of the study was to assess safety and efficacy of autologous muscle derived cells for urinary sphincter repair (AMDC-USR) in female subjects with predominant stress urinary incontinence. METHODS: A randomized, double-blind, multicenter trial examined intra-sphincteric injection of 150 × 106 AMDC-USR versus placebo in female subjects with stress or stress predominant, mixed urinary incontinence. AMDC-USR products were generated from vastus lateralis needle biopsies. Subjects were randomized 2:1 to receive AMDC-USR or placebo and 1:1 to receive 1 or 2 treatments (6 months after the first). Primary outcome was composite of ≥ 50% reduction in stress incontinence episode frequency (IEF), 24-h or in-office pad weight tests at 12 months. Other outcome data included validated subject-recorded questionnaires. Subjects randomized to placebo could elect to receive open-label AMDC-USR treatment after 12 months. Subject follow-up was up to 2 years. RESULTS: AMDC-USR was safe and well-tolerated with no product-related serious adverse events or discontinuations due to adverse events. Interim analysis revealed an unexpectedly high placebo response rate (90%) using the composite primary outcome which prevented assessment of treatment effect as designed and thus enrollment was halted at 61% of planned subjects. Post hoc analyses suggested that more stringent endpoints lowered placebo response rates and revealed a possible treatment effect. CONCLUSIONS: Although the primary efficacy finding was inconclusive, these results inform future trial design of AMDC-USR to identify clinically meaningful efficacy endpoints based on IEF reduction, understanding of placebo response rate, and refinement of subject selection criteria to more appropriately align with AMDC-USR's proposed mechanism of action.

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.

Enhancement of bone healing based on ex vivo gene therapy using human muscle-derived cells expressing bone morphogenetic protein 2.

Molecular biological advances have allowed the use of gene therapy in a clinical setting. In addition, numerous reports have indicated the existence of inducible osteoprogenitor cells in skeletal muscle. Because of this, we hypothesized that skeletal muscle cells might be ideal vehicles for delivery of bone-inductive factors. Using ex vivo gene transfer methods, we genetically engineered freshly isolated human skeletal muscle cells with adenovirus and retrovirus to express human bone morphogenetic protein 2 (BMP-2). These cells were then implanted into nonhealing bone defects (skull defects) in severe combined immune deficiency (SCID) mice. The closure of the defect was monitored grossly and histologically. Mice that received BMP-2-producing human muscle-derived cells experienced a full closure of the defect by 4 to 8 weeks posttransplantation. Remodeling of the newly formed bone was evident histologically during the 4- to 8-week period. When analyzed by fluorescence in situ hybridization, a small fraction of the transplanted human muscle-derived cells was found within the newly formed bone, where osteocytes normally reside. These results indicate that genetically engineered human muscle-derived cells enhance bone healing primarily by delivering BMP-2, while a small fraction of the cells seems to differentiate into osteogenic cells.

In vitro and in vivo effect of lidocaine on rat muscle-derived cells for treatment of stress urinary incontinence.

OBJECTIVES: Lidocaine cytotoxicity has been reported in some cell types, which could affect its use as a local anesthetic in cell-based therapy. We evaluated the in vitro and in vivo effect of lidocaine on rat muscle-derived progenitor cells (MDCs). METHODS: MDCs were isolated from rat skeletal muscle and purified using the preplate technique. For in vitro tests, the MDCs underwent either 2 hours of, or continuous, exposure to lidocaine (50 microM-5 mM). After 72 hours of incubation, cell viability was measured using the methylthiazololetetrazolium assay. For the in vivo tests, periurethral injection of either phosphate-buffered saline, MDCs (1 x 10(6) cells/20 microL), or 2% lidocaine plus MDCs was performed in pudendal nerve-transected rats. The leak point pressure (LPP) was measured at 4 weeks after the injection. RESULTS: Lidocaine concentrations of < or = 500 microM had no effect on MDCs with continuous exposure. MDCs in 1 mM lidocaine showed decreased survival and no MDCs in 5 mM lidocaine survived. With a 2-hour exposure, only MDCs in the 5-mM lidocaine group showed decreased survival. Rats with nerve transection and phosphate-buffered saline injection showed significantly lower LPPs than the controls. The LPP was restored to a significantly greater level after MDCs only or lidocaine plus MDC injection. No statistically significant difference in LPP restoration was found between the MDC-only and lidocaine plus MDC injections. CONCLUSIONS: Cytotoxicity to lidocaine was minimal at a physiologic concentration in vitro. The functional recovery of LPP by MDC treatment was not affected by lidocaine preinfiltration. Taken together, our data indicate that lidocaine can be applied as a local anesthetic in periurethral MDC injection without decreasing the efficacy of the therapy.

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

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

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

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

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.

Ex vivo biomechanical properties of the female urethra in a rat model of birth trauma.

Stress urinary incontinence (SUI) is the involuntary release of urine during sudden increases in abdominal pressures. SUI is common in women after vaginal delivery or pelvic trauma and may alter the biomechanical properties of the urethra. Thus we hypothesize that injury due to vaginal distension (VD) decreases urethral basal tone and passive stiffness. This study aimed to assess the biomechanical properties of the urethra after VD in the baseline state, where basal muscle tone and extracellular matrix (ECM) are present, and in the passive state, where inactive muscle and ECM are present. Female rat urethras were isolated in a rat model of acute SUI induced by simulated birth trauma. Our established ex vivo system was utilized, wherein we applied intraluminal static pressures ranging from 0 to 20 mmHg. Outer diameter was measured via a laser micrometer. Measurements were recorded via computer. Urethral thickness was assessed histologically. Stress-strain responses of the urethra were altered by VD. Quantification of biomechanical parameters indicated that VD decreased baseline stiffness. The passive peak incremental elastic modulus of the distal segment in VD urethras was less than for controls (1.84 +/- 0.67 vs. 1.19 +/- 0.70 x 10(6) dyne/cm(2), respectively; P = 0.016). An increase was noted in passive low-pressure compliance values in proximal VD urethras compared with controls (9.44 +/- 2.43 vs. 4.62 +/- 0.60 mmHg(-1), respectively; P = 0.04). Biomechanical analyses suggest that VD alters urethral basal tone, proximal urethral compliance, and distal stiffness. Lack of basal smooth muscle tone, in combination with these changes in the proximal and distal urethra, may contribute to SUI induced by VD.

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

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

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.

Biomechanical characterization of the urethral musculature.

Rigorous study of the associations between urethral structural anatomy and biomechanical function is necessary to advance the understanding of the development, progression, and treatment of urethral pathologies. An ex vivo model was utilized to define the relative biomechanical contributions of the active (muscle) elements of the female urethra relative to its passive (noncontractile) elements. Whole urethras from female, adult rats were tested under a range of applied intraluminal pressures (0 to 20 mmHg) as a laser micrometer simultaneously measured midurethral outer diameter. Active tissue characterization was performed during induced contraction of either smooth muscle alone (N(omega)-nitro-l-arginine, phenylephrine), striated muscle alone (sodium nitroprusside, atropine, hexamethonium, acetylcholine), or during collective activation of both muscles (N(omega)-nitro-l-arginine, phenylephrine, acetylcholine). The subsequent collection of paired passive biomechanical responses permitted the determination of parameters related to intrinsic muscle contractile function. Activation of each muscle layer significantly influenced the biomechanical responses of the tissue. Measures of muscle responsiveness over a wide range of sustained opposing pressures indicated that an activated striated muscle component was approximately one-third as effective as activated smooth muscle in resisting tissue deformation. The maximum circumferential stress generated by the striated muscle component under these conditions was also determined to be approximately one-third of that generated by the smooth muscle (748 +/- 379 vs. 2,229 +/- 409 N/m(2)). The experiments quantitatively reveal the relative influence of the intrinsic urethral smooth and striated muscle layers with regard to their effect on the mechanical properties and maximum functional responses of the urethra to applied intralumenal stresses in the complete absence of extrinsic influences.

Establishing reliable criteria for isolating myogenic cell fractions with stem cell properties and enhanced regenerative capacity.

Despite a focused effort within the myogenic cell transplantation community, little progress has been made toward the reliable identification and isolation of progenitors that are capable of tolerating the initial posttransplantation environment and effectively regenerating clinically relevant quantities of muscle. The future success of myogenic-based treatment modalities requires an enhanced understanding of the highly heterogeneous nature of the myogenic progenitor cell pool, which has been previously documented by numerous researchers. Further, for translation of experimental animal results to clinical application, reliable in vitro selection criteria must be established and must be translatable across species. While research into the utility of surface markers is ongoing, as an alternative we have investigated in vitro cell behavioral characteristics under imposed conditions which challenge the propensity of myogenic progenitors to choose between various cell fates (i.e., proliferation, quiescence, or differentiation). Previous observations in the mouse suggest an enhanced in vivo regenerative capacity of myogenic populations with respect to their in vitro ability to maintain a proliferative and undifferentiated state [J. Cell Sci. 115 (2002) 4361]. From these observations it is thus proposed that such behavior may represent an a priori indicator of regenerative capacity following transplantation. To challenge this proposition, a rat cell isolation and transplantation model was evaluated in an identical manner. In agreement with the results obtained from the mouse, a significant correlation between regenerative capacity and induction of differentiation was observed. These results contribute to the growing body of scientific evidence documenting the underlying behavioral differences that exist between various myogenic progenitors while also, importantly, providing evidence that such differences may significantly impact the functional capabilities of these cells posttransplantation. This information further implies that from a therapeutic standpoint isolation strategies aimed toward obtaining efficient myogenic progenitors should, in the absence of a reliable surface marker(s), focus on identifying populations displaying desirable in vitro behavior (i.e., high proliferative capacity and low induced differentiation). Incorporating such criteria into cell isolation and/or purification schemes may yield significant returns in the clinical myogenic transplantation setting.