Stem cell therapy for urinary incontinence and pelvic floor disorders: a novel approach

Status, challenges, and future prospects of stem cell therapy in pelvic floor disorders

Pelvic floor disorders (PFDs) represent a group of common and frequently-occurring diseases that seriously affect the life quality of women, generally including stress urinary incontinence and pelvic organ prolapse. Surgery has been used as a treatment for PFD, but almost 30% of patients require subsequent surgery due to a high incidence of postoperative complications and high recurrence rates. Therefore, investigations of new therapeutic strategies are urgently needed. Stem cells possess strong multi-differentiation, self-renewal, immunomodulation, and angiogenesis abilities and they are able to differentiate into various cell types of pelvic floor tissues and thus provide a potential therapeutic approach for PFD. Recently, various studies using different autologous stem cells have achieved promising results by improving the pelvic ligament and muscle regeneration and conferring the tissue elasticity and strength to the damaged tissue in PFD, as well as reduced inflammatory reactions, collagen deposition, and foreign body reaction. However, with relatively high rates of complications such as bladder stone formation and wound infections, further studies are necessary to investigate the role of stem cells as maintainers of tissue homeostasis and modulators in early interventions including therapies using new stem cell sources, exosomes, and tissue-engineering combined with stem cell-based implants, among others. This review describes the types of stem cells and the possible interaction mechanisms in PFD treatment, with the hope of providing more promising stem cell treatment strategies for PFD in the future.

Induction of human umbilical cord mesenchymal stem cells into tissue-forming cells in a murine model: implications for pelvic floor reconstruction

HUMSCs were isolated, differentiated and characterized in vitro. Both HUMSCs and smooth muscle cells differentiated from HUMSCs were used to fabricate tissue-engineered fascia equivalents. Forty-eight mature female Sprague Dawley rats were randomly assigned to four groups: group A (GynemeshTMPS, n = 12), group B (GynemeshTMPS + HUMSCs; n = 12), group C (GynemeshTMPS + smooth muscle cells differentiated from HUMSCs; n = 12) and group D (GynemeshTMPS + HUMSCs + smooth muscle cells differentiated from HUMSCs; n = 12). The posterior vaginal wall was incised from the introitus and the mesh was then implanted. Three implants of each type were tested at 1, 4, 8 and 12 weeks. Fibrotic remodeling, inflammation, vascularization and tissue regeneration were histologically assessed. The levels of type I and type III collagen were determined. There was no difference in fibrotic remodeling between cell-seeded and unseeded meshes at any time (p > 0.05). At 12 weeks, there did not appear to be fewer inflammatory cells around the filament bundles in the mesh with cells compared with the mesh alone (P > 0.05). Group D showed a trend toward better vascularization at 12 weeks compared with group A (P < 0.05). Twelve weeks after implantation, a thin layer of new tissue growth covered the unseeded scaffold and a thicker layer covered the cell-seeded scaffold (P < 0.05). No significant difference in the ratio of collagen type I/III could be detected among the different groups after 12 weeks (P > 0.05). HUMSCs with differentiated smooth muscle cells might have a potential role in fascia tissue engineering to repair POP in the future.

Periurethral muscle-derived mononuclear cell injection improves urethral sphincter restoration in rats

AIMS

Investigate the effect of a novel cell-based therapy with skeletal muscle-derived mononuclear cells (SMDMCs) in a rat model of stress urinary incontinence.

METHODS

Male Wistar-Kyoto rats' hind limb muscles were enzymatically dissociated, and SMDMCs were isolated without needing expansion. The cell population was characterized. Twenty female rats underwent urethrolysis. One week later, 10 rats received periurethral injection of 10⁶ cells (SMDMC group), and 10 rats received saline injections (Saline group). Ten rats underwent sham surgery (Sham group). Four weeks after injection, animals were euthanized and the urethra was removed. The incorporation of SMDMCs in the female urethra was evaluated with fluorescence in situ hybridization for the detection of Y-chromosomes. Hematoxylin and eosin, Masson's trichrome staining, and immunohistochemistry for actin and myosin were performed. The muscle/connective tissue, actin and myosin ratios were calculated. Morphological evaluation of the urethral diameters and fractional areas of the lumen, mucosa, and muscular layer was performed.

RESULTS

SMDMCs population was consistent with the presence of muscle cells, muscle satellite cells, perivascular cells, muscle progenitor cells, and endothelial cells. SMDMCs were incorporated into the urethra. A significant decrease in the muscle/connective tissue ratio was observed in the Saline group compared with the SMDMC and Sham groups. The proportions of actin and myosin were significantly decreased in the Saline group. No differences were observed in the morphometric parameters.

CONCLUSIONS

SDMSC were incorporated into the rat urethra and promoted histological recovery of the damaged urethral sphincter, resulting in decreased connective tissue deposition and increased muscle content.

Tissue-engineered fascia from vaginal fibroblasts for patients needing reconstructive pelvic surgery

INTRODUCTION AND HYPOTHESIS

Mesh-augmented reconstructive surgery for pelvic organ prolapse (POP) does not meet clinical expectations. A tissue-engineered fascia equivalent needs to be developed.

METHODS

Human vaginal fibroblasts (HVFs) from 10 patients were characterized in vitro. Eligible HVFs and a biodegradable scaffold were used to fabricate a fascia equivalent, which was then transplanted in vivo.

RESULTS

The cultured HVFs were divided into high (n = 6) or low (n = 4) collagen I/III ratio groups. Cells of the high-ratio group exhibited significantly higher proliferation potential than those of the low-ratio group (P < 0.05). A fascia equivalent was made with HVFs of the high-ratio group. In the subsequent animal study, a well-organized neo-fascia formation containing HVFs could be traced up to 12 weeks after transplantation.

CONCLUSIONS

Our results suggest that a tissue-engineered fascia could be developed from HVFs in vitro and in vivo, which might be an effective treatment for POP in the future.

Over expression of stem cell homing cytokines in urogenital organs following vaginal distention

PURPOSE

Vaginal delivery is a risk factor for stress urinary incontinence. Rat models of simulated childbirth demonstrated hypoxia of the urogenital organs as well as the development of stress urinary incontinence following vaginal distention. Stromal derived factor-1 and monocyte chemotactic protein-3 were identified as cytokines that are over expressed after myocardial ischemia and signal stem cell migration to ischemic sites in a rat cardiac model. Given the focal hypoxia observed with vaginal distention, we characterized stromal derived factor-1 and monocyte chemotactic protein-3 expression by pelvic organ tissues after vaginal distention.

MATERIALS AND METHODS

A total of 16 female rats were randomized into 4 groups. Two groups underwent vaginal distention with harvest of pelvic tissues immediately or 24 hours after vaginal distention, a sham group underwent anesthesia only and a control group underwent no intervention. Reverse transcriptase-polymerase chain reaction was performed on RNA extracted from the urogenital organs.

RESULTS

Monocyte chemotactic protein-3 expression in the urethra was increased 20 and 6-fold immediately and 24 hours after vaginal distention, respectively. Monocyte chemotactic protein-3 was 8 and 4-fold increased in the vagina after vaginal distention. There was no difference in monocyte chemotactic protein-3 expression in the rectum or bladder in any group. Stromal derived factor-1 was significantly under expressed immediately after vaginal distention in all tissues.

CONCLUSIONS

Monocyte chemotactic protein-3 is significantly over expressed in rat urethral and vaginal tissues immediately following vaginal distention with above normal but decreasing expression 24 hours later. The association between monocyte chemotactic protein-3 over expression and targeted stem cell migration is under investigation. Successful characterization and control of such a repair mechanism in the lower urinary tract would introduce the potential for novel nonoperative treatments and/or preventive measures for stress urinary incontinence.