Sphincter contractility after muscle-derived stem cells autograft into the cryoinjured anal sphincters of rats

Stem cell therapy combined with controlled release of growth factors for the treatment of sphincter dysfunction

Sphincter dysfunction often occurs at the end of tubule organs such as the urethra, anus, or gastroesophageal sphincters. It is the primary consequence of neuromuscular impairment caused by trauma, inflammation, and aging. Despite intensive efforts to recover sphincter function, pharmacological treatments have not achieved significant improvement. Cell- or growth factor-based therapy is a promising approach for neuromuscular regeneration and the recovery of sphincter function. However, a decrease in cell retention and viability, or the short half-life and rapid degradation of growth factors after implantation, remain obstacles to the translation of these therapies to the clinic. Natural biomaterials provide unique tools for controlled growth factor delivery, which leads to better outcomes for sphincter function recovery in vivo when stem cells and growth factors are co-administrated, in comparison to the delivery of single therapies. In this review, we discuss the role of stem cells combined with the controlled release of growth factors, the methods used for delivery, their potential therapeutic role in neuromuscular repair, and the outcomes of preclinical studies using combination therapy, with the hope of providing new therapeutic strategies to treat incontinence or sphincter dysfunction of the urethra, anus, or gastroesophageal tissues, respectively.

Differentiation of Adipose-Derived Stem Cells into Smooth Muscle Cells in an Internal Anal Sphincter-Targeting Anal Incontinence Rat Model

OBJECTIVE

Studies on development of an anal incontinence (AI) model targeting smooth muscle cells (SMCs) of the internal anal sphincter (IAS) have not been reported. The differentiation of implanted human adipose-derived stem cells (hADScs) into SMCs in an IAS-targeting AI model has also not been demonstrated. We aimed to develop an IAS-targeting AI animal model and to determine the differentiation of hADScs into SMCs in an established model.

MATERIALS AND METHODS

The IAS-targeting AI model was developed by inducing cryoinjury at the inner side of the muscular layer via posterior intersphincteric dissection in Sprague-Dawley rats. Dil-stained hADScs were implanted at the IAS injury site. Multiple markers for SMCs were used to confirm molecular changes before and after cell implantation. Analyses were performed using H&E, immunofluorescence, Masson's trichrome staining, and quantitative RT-PCR.

RESULTS

Impaired smooth muscle layers accompanying other intact layers were identified in the cryoinjury group. Specific SMC markers, including SM22α, calponin, caldesmon, SMMHC, smoothelin, and SDF-1 were significantly decreased in the cryoinjured group compared with levels in the control group. However, CoL1A1 was increased significantly in the cryoinjured group. In the hADSc-treated group, higher levels of SMMHC, smoothelin, SM22α, and α-SMA were observed at two weeks after implantation than at one week after implantation. Cell tracking revealed that Dil-stained cells were located at the site of augmented SMCs.

CONCLUSIONS

This study first demonstrated that implanted hADSc restored impaired SMCs at the injury site, showing stem cell fate corresponding to the established IAS-specific AI model.

The Effect of Mesenchymal Stem Cells, Adipose Tissue Derived Stem Cells, and Cellular Stromal Vascular Fraction on the Repair of Acute Anal Sphincter Injury in Rats

Background: Anal sphincter incontinence (ASI) can cause a serious decline in the quality of life and can cause a socioeconomic burden. Studies have shown that bone marrow mesenchymal stem cells (MSC) have significant therapeutic effects on ASI, but the cost and risk of MSC harvest limit their further application. In contrast, adipose tissue derived stem cells (ADSC) and cellular stromal vascular fraction (CSVF) as stem cell sources have multipotency and the advantage of easy harvest. Objective: Here we aim to investigate the effects of ADSC and CSVF on treating ASI and compare them to that of bone marrow MSC. Methods: Bone marrow MSC, ADSC, and CSVF were obtained and labeled with green fluorescent protein (GFP), and CSVF was labeled with DIL. Sprague Dawley (SD) rats were divided into 5 groups. Four groups were injected with 0.2 mL phosphate buffer saline (PBS), 1 × 107/0.2 mL of MSC, ADSC, or CSVF, respectively, after model establishment. The control group received no treatment. The repair was assessed by anal functional tests and immunostaining on day 5 and day 10 after injection. Results: MSC, ADSC, and CSVF significantly promoted tissue repair and the recovery of muscle contraction and electromyographic activity in ASI. The generation of myosatellite cells by injected MSC, ADSC, and CSVF was found in the wounded area. On day 5, CSVF showed highest therapeutic effect, while on day 10, MSC and ADSC showed higher therapeutic effects than CSVF. When comparing the effects of MSC and ADSC, ADSC was slightly better than MSC in the indexes of anal pressure, etc. Conclusion: ADSC and CVSF are alternative stem cell sources for ASI repair.

Stromal cell derived factor 1 plasmid to regenerate the anal sphincters

The aim of this study was to evaluate regeneration of a chronic large anal sphincter defect in a pig model after treatment with a plasmid encoding Stromal Cell Derived Factor-1(SDF-1).

METHODS

Under ethics approved protocol 19 age/weight matched Sinclair mini-pigs were subjected to excision of the posterior 50% of anal sphincter muscle and left to recover for 6 weeks. They were randomly allocated to receive either saline treatment (Saline 1 ml, n = 5), 1 injection of SDF-1 plasmid 2 mg/ml (1 SDF-1, n = 9) or 2 injections of SDF-1, 2 mg/ml each at 2 weeks intervals (2 SDF-1, n = 5). Euthanasia occurred 8 weeks after the last treatment. In vivo outcomes included anal resting pressures done under anesthesia pre-injury, pre-injection and before euthanasia (8 weeks after treatment). Anal ultrasound was done pre injury and pre-euthanasia. Tissues were saved for histology and analyzed quantitatively. Two way ANOVA followed by Holm-Sidak test and one way ANOVA followed by the Tukey test were used for data analysis, p < 0.05 was regarded as significant.

RESULTS

Posterior anal pressures at the 3 time points were not significantly different in the saline group. In contrast, post-treatment pressures in the 1 SDF-1 group pressures were significantly higher than both pre-injury (p = 0.001) and pre-treatment time points (p = 0.003). At the post-treatment time point, both 1 SDF-1 (p = 0.01) and 2 SDF-1 (p = 0.01) groups had significantly higher mean pressures compared to the saline group. Histology showed distortion of normal anatomy with patchy regeneration in the control group while muscle was more organized in both treatment groups.

CONCLUSIONS

Eight weeks after a single or two doses of SDF-1injected into a chronic anal sphincter injury improved resting anal pressures and regenerated muscle in the entire defect. SDF-1 plasmid is effective in treating chronic defects of the anal sphincter in a large animal and could be clinically translated.

Cell Therapy for Anal Sphincter Incontinence: Where Do We Stand?

Anal sphincter incontinence is a chronic disease, which dramatically impairs quality of life and induces high costs for the society. Surgery, considered as the best curative option, shows a disappointing success rate. Stem/progenitor cell therapy is pledging, for anal sphincter incontinence, a substitute to surgery with higher efficacy. However, the published literature is disparate. Our aim was to perform a review on the development of cell therapy for anal sphincter incontinence with critical analyses of its pitfalls. Animal models for anal sphincter incontinence were varied and tried to reproduce distinct clinical situations (acute injury or healed injury with or without surgical reconstruction) but were limited by anatomical considerations. Cell preparations used for treatment, originated, in order of frequency, from skeletal muscle, bone marrow or fat tissue. The characterization of these preparations was often incomplete and stemness not always addressed. Despite a lack of understanding of sphincter healing processes and the exact mechanism of action of cell preparations, this treatment was evaluated in 83 incontinent patients, reporting encouraging results. However, further development is necessary to establish the correct indications, to determine the most-suited cell type, to standardize the cell preparation method and to validate the route and number of cell delivery.

Treatment of faecal incontinence with autologous expanded mesenchymal stem cells: results of a pilot study

AIM

Management of faecal incontinence (FI) remains challenging because no definitive optimal treatment for this condition has yet been determined. Regenerative medicine could be an attractive therapeutic alternative for treating FI. Here, we aimed to determine the safety and feasibility of autologous expanded mesenchymal stem cells derived from adipose tissue (AdMSCs) in the treatment of patients diagnosed with structural FI.

METHOD

This was a randomized, multicentre, triple-blinded, placebo-controlled pilot study conducted at four sites in Spain with 16 adults with FI and a sphincter defect. Autologous AdMSCs were obtained from patients from surgically excised adipose tissue. These patients were intralesionally infused with a single dose of 4 × 10⁷ AdMSCs or a placebo while under anaesthesia. We assessed the safety and feasibility of the treatment as the cumulative incidence of adverse events and the treatment efficacy using the Cleveland Clinic Faecal Incontinence Score, Faecal Incontinence Quality of Life score and Starck criteria to classify sphincter defects and anorectal physiology outcomes.

RESULTS

Adipose tissue extraction, cell isolation and intralesional infusion procedures were successful in all the patients. There was only one adverse event connected to adipose tissue extraction (a haematoma), and none was associated with the injection procedure. There were no significant differences in any of the assessed clinical, manometric or ultrasonographic parameters.

CONCLUSION

This study indicates that this infusion procedure in the anal sphincter is feasible and safe. However, it failed to demonstrate efficacy to treat patients with structural FI.

What Is Fecal Incontinence That Urologists Need to Know?

Fecal incontinence (FI) undoubtedly reduces quality of life and adversely affects the social life of the affected individual. FI has a higher prevalence with age and has an equivalent prevalence to urinary incontinence in patients with genitourinary disease, but is often not confirmed in these cases. A thorough investigation is needed to diagnose FI, with the common etiology of this condition in mind, and several questionnaires can be used to identify symptoms. The physical examination contains digital rectal examination carries out to identify the patient's condition. Ultrasound, colonoscopy, and rectum pressure test can be performed. Patients educated in diet-related issues, bowel movements, and defecation mechanism. Nonoperative options such as diet control and Kegel exercise should be performed at first. Surgical treatment of FI is considered when conservative management and oral medications produce no improvement. Surgical options include less invasive procedures like bulking agent injections, and more involved approaches from sacral nerve stimulation to invasive direct sphincter repair and artificial bowel sphincter insertion. Good outcomes in FI cases have also recently been reported for barrier devices.

Regenerative medicine for anal incontinence: a review of regenerative therapies beyond cells

INTRODUCTION AND HYPOTHESIS

Current treatment modalities for anal sphincter injuries are ineffective for many patients, prompting research into restorative and regenerative therapies. Although cellular therapy with stem cells and progenitor cells show promise in animal models with short-term improvement, there are additional regenerative approaches that can augment or replace cellular therapies for anal sphincter injuries. The purpose of this article is to review the current knowledge of cellular therapies for anal sphincter injuries and discusses the use of other regenerative therapies including cytokine therapy with CXCL12.

METHODS

A literature search was performed to search for articles on cellular therapy and cytokine therapy for anal sphincter injuries and anal incontinence.

RESULTS

The article search identified 337 articles from which 33 articles were included. An additional 12 referenced articles were included as well as 23 articles providing background information. Cellular therapy has shown positive results for treating anal sphincter injuries and anal incontinence in vitro and in one clinical trial. However, cellular therapy has disadvantages such as the source and processing of stem cells and progenitor cells. CXCL12 does not have such issues while showing promising in vitro results for treating anal sphincter injuries. Additionally, electrical stimulation and extracorporeal shock wave therapy are potential regenerative medicine adjuncts for anal sphincter injuries. A vision for future research and clinical applications of regenerative medicine for anal sphincter deficiencies is provided.

CONCLUSION

There are viable regenerative medicine therapies for anal sphincter injuries beyond cellular therapy. CXCL12 shows promise as a focus of therapeutic research in this field.

Recent advances in managing fecal incontinence

Fecal incontinence (FI) is the uncontrolled passage of feces or gas in an individual who previously had control. The prevalence of the problem varies but can be as high as 50% of institutionalized individuals. The severity varies among individuals, but the negative impact on self-esteem and quality of life can have devastating effects. The goals of treatment are to decrease the frequency and severity of episodes as well as to improve quality of life. At present, several therapies, ranging from medical management to more invasive surgical interventions, are offered for the management of FI. In this article, we review the most recent advances in the management of FI.

Cell therapy to improve regeneration of skeletal muscle injuries

Diseases that jeopardize the musculoskeletal system and cause chronic impairment are prevalent throughout the Western world. In Germany alone, ~1.8 million patients suffer from these diseases annually, and medical expenses have been reported to reach 34.2bn Euros. Although musculoskeletal disorders are seldom fatal, they compromise quality of life and diminish functional capacity. For example, musculoskeletal disorders incur an annual loss of over 0.8 million workforce years to the German economy. Among these diseases, traumatic skeletal muscle injuries are especially problematic because they can occur owing to a variety of causes and are very challenging to treat. In contrast to chronic muscle diseases such as dystrophy, sarcopenia, or cachexia, traumatic muscle injuries inflict damage to localized muscle groups. Although minor muscle trauma heals without severe consequences, no reliable clinical strategy exists to prevent excessive fibrosis or fatty degeneration, both of which occur after severe traumatic injury and contribute to muscle degeneration and dysfunction. Of the many proposed strategies, cell-based approaches have shown the most promising results in numerous pre-clinical studies and have demonstrated success in the handful of clinical trials performed so far. A number of myogenic and non-myogenic cell types benefit muscle healing, either by directly participating in new tissue formation or by stimulating the endogenous processes of muscle repair. These cell types operate via distinct modes of action, and they demonstrate varying levels of feasibility for muscle regeneration depending, to an extent, on the muscle injury model used. While in some models the injury naturally resolves over time, other models have been developed to recapitulate the peculiarities of real-life injuries and therefore mimic the structural and functional impairment observed in humans. Existing limitations of cell therapy approaches include issues related to autologous harvesting, expansion and sorting protocols, optimal dosage, and viability after transplantation. Several clinical trials have been performed to treat skeletal muscle injuries using myogenic progenitor cells or multipotent stromal cells, with promising outcomes. Recent improvements in our understanding of cell behaviour and the mechanistic basis for their modes of action have led to a new paradigm in cell therapies where physical, chemical, and signalling cues presented through biomaterials can instruct cells and enhance their regenerative capacity. Altogether, these studies and experiences provide a positive outlook on future opportunities towards innovative cell-based solutions for treating traumatic muscle injuries-a so far unmet clinical need.

Regenerative medicine as a therapeutic option for fecal incontinence: a systematic review of preclinical and clinical studies

BACKGROUND

Fecal incontinence is the uncontrollable loss of stool and has a prevalence of around 7-15%. This condition has serious implications for patients' quality of life. Current treatment options show unsatisfactory results. A novel treatment option is therefore needed.

OBJECTIVE

This systematic review aims to perform a quality assessment and to give a critical overview of the current research available on regenerative medicine as a treatment for fecal incontinence.

STUDY DESIGN

A systematic search strategy was applied in PubMed, Cochrane Library, EMBASE, MEDLINE, Web of Science, and Cinahl from inception until March of 2018. Studies were found relevant when the animals or patients in the studied group had objectively determined or induced fecal incontinence, and the intervention must have used any kind of cells, stem cells, or biocompatible material, with or without the use of trophic factors. Studies were screened on title and consecutively on abstract for relevance by 2 independent investigators. The risk of bias of preclinical studies was assessed using the SYstematic Review Centre for Laboratory animal Experimentation risk of bias tool for animal studies, and for clinical studies the Cochrane risk of bias tool for randomized trials was used.

RESULTS

In all, 34 preclinical studies and 5 clinical studies were included. Animal species, type of anal sphincter injury, intervention, and outcome parameters were heterogenous. Therefore, a meta-analysis could not be performed. The overall risk of bias of the included studies was high.

CONCLUSION

The efficacy of regenerative medicine to treat fecal incontinence could not be determined due to the high risk of bias and heterogenicity of the available preclinical and clinical studies. The findings of this systematic review may result in improved study design of future studies, which could help the translation of regenerative medicine to the clinic as an alternative to current treatments for fecal incontinence.

Isolation of internal and external sphincter progenitor cells from the human anal sphincter with or without radiotherapy

AIM

We aimed to isolate and propagate internal and external anal sphincter progenitor cells from the human anal sphincter, with or without radiotherapy, for tailored cell therapy of faecal incontinence.

METHODS

Sphincter progenitor cells were isolated from normal internal and external anal sphincters collected from 10 patients with rectal cancer who had undergone abdominoperineal resection with (n = 6) or without (n = 4) preoperative chemoradiotherapy. The isolated cells and differentiated muscle fibres were identified using immunofluorescence assay, western blotting and reverse transcription polymerase chain reaction (RT-PCR). The proliferation of progenitor cells with and without radiotherapy was compared by quantitative 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

RESULTS

The immunofluorescence assay before differentiation confirmed that the internal anal sphincter progenitor cells expressed CD34 and neural-glial antigen 2 (NG2), whereas the external anal sphincter progenitor cells expressed CD34 and PAX7. After differentiation, the internal anal sphincter progenitor cells expressed desmin, calponin and α-smooth muscle actin, whereas the external anal sphincter progenitor cells expressed desmin, myogenic factor 4 and myosin heavy chain. The differential expression profiles of both cell types were confirmed by western blotting and RT-PCR. MTT assays showed that the viability of internal and external anal sphincter progenitor cells was significantly lower in the radiotherapy group than that in the nonradiotherapy group.

CONCLUSIONS

This study describes the differential harvest internal and external sphincter muscle progenitor cells from human anal sphincters. We confirm that radiotherapy decreases the viability of internal and external anal sphincter progenitor cells.

Stem cell therapy for faecal incontinence: Current state and future perspectives

Faecal continence is a complex function involving different organs and systems. Faecal incontinence is a common disorder with different pathogeneses, disabling consequences and high repercussions for quality of life. Current management modalities are not ideal, and the development of new treatments is needed. Since 2008, stem cell therapies have been validated, 36 publications have appeared (29 in preclinical models and seven in clinical settings), and six registered clinical trials are currently ongoing. Some publications have combined stem cells with bioengineering technologies. The aim of this review is to identify and summarise the existing published knowledge of stem cell utilization as a treatment for faecal incontinence. A narrative or descriptive review is presented. Preclinical studies have demonstrated that cellular therapy, mainly in the form of local injections of muscle-derived (muscle derived stem cells or myoblasts derived from them) or mesenchymal (bone-marrow- or adipose-derived) stem cells, is safe. Cellular therapy has also been shown to stimulate the repair of both acute and subacute anal sphincter injuries, and some encouraging functional results have been obtained. Stem cells combined with normal cells on bioengineered scaffolds have achieved the successful creation and implantation of intrinsically-innervated anal sphincter constructs. The clinical evidence, based on adipose-derived stem cells and myoblasts, is extremely limited yet has yielded some promising results, and appears to be safe. Further investigation in both animal models and clinical settings is necessary to drawing conclusions. Nevertheless, if the preliminary results are confirmed, stem cell therapy for faecal incontinence may well become a clinical reality in the near future.

A gene expression profile analysis of the differentiation of muscle-derived stem cells into smooth muscle cells from sheep

OBJECTIVE

To analyze gene expression profiles analysis during the differentiation of sheep muscle-derived stem cells (MDSCs) into smooth muscle cells (SMCs) in sheep.

METHODS

A modified preplate technique was employed to isolation of the MDSCs from sheep. The MDSCs were subjected to flow cytometry analysis targeting CD44, CD31, CD45, CD14, and CD49f and were treated with TGF-β1 at a concentration of 10 ng/ml for ten days. The expression levels of smooth muscle α-actin (α-SMA) and calponin after treatment with TGF-β1 were determined by western blotting and immunofluorescence staining. A microarray analysis was performed to screen for differentially expressed genes (DEGs) during MDSC differentiation using total RNA extracted from MDSCs and SMCs generated from MDSCs. Molecule Annotation System (MAS) 3.0, which employs KEGG (Kyoto Encyclopedia of Genes and Genomes) and GO (Gene Ontology) Consortium annotations, was used to identify global biological trends in the gene expression data.

RESULTS

The expression levels of the SMC-specific contractile proteins α-SMA and calponin were dramatically increased after treatment with TGF-β1. Immunofluorescece staining showed that the TGF-β1-treated MDSCs were positive for α-SMA. We identified 486 genes that were differentially expressed between the MDSCs and TGF-β1-treated MDSCs. 260 of which were up-regulated and 226 of which were down-regulated. Twenty-one genes exhibited a greater than ten-fold change, 13 of which were up-regulated and 8 of which were down-regulated. TGF-β1 treatment up-regulated both the SMAD and MAPK signaling pathways during the differentiation of these sheep cells. The PPAR and Wnt signaling pathways were also found to be involved in the differentiation process.

CONCLUSIONS

TGF-β1 can successfully induce the differentiation of sheep MDSCs into SMCs. For the first time, we analyzed the gene expression profiles associated with this differentiation process, and the results showed that both the SMAD and MAPK signaling pathways are involved. This study indicated that multiple signaling networks coordinate the development and differentiation of MDSCs into SMCs.

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

Rat model of anal sphincter injury and two approaches for stem cell administration

AIM

To establish a rat model of anal sphincter injury and test different systems to provide stem cells to injured area.

METHODS

Adipose-derived stem cells (ASCs) were isolated from BDIX rats and were transfected with green fluorescent protein (GFP) for cell tracking. Biosutures (sutures covered with ASCs) were prepared with 1.5 x 10⁶ GFP-ASCs, and solutions of 10⁶ GFP-ASCs in normal saline were prepared for injection. Anorectal normal anatomy was studied on Wistar and BDIX female rats. Then, we designed an anal sphincter injury model consisting of a 1-cm extra-mucosal miotomy beginning at the anal verge in the anterior middle line. The sphincter lesion was confirmed with conventional histology (hematoxylin and eosin) and immunofluorescence with 4', 6-diamidino-2-phenylindole (commonly known as DAPI), GFP and α-actin. Functional effect was assessed with basal anal manometry, prior to and after injury. After sphincter damage, 36 BDIX rats were randomized to three groups for: (1) Cell injection without repair; (2) biosuture repair; and (3) conventional suture repair and cell injection. Functional and safety studies were conducted on all the animals. Rats were sacrificed after 1, 4 or 7 d. Then, histological and immunofluorescence studies were performed on the surgical area.

RESULTS

With the described protocol, biosutures had been covered with at least 820000-860000 ASCs, with 100% viability. Our studies demonstrated that some ASCs remained adhered after suture passage through the muscle. Morphological assessment showed that the rat anal anatomy is comparable with human anatomy; two sphincters are present, but the external sphincter is poorly developed. Anal sphincter pressure data showed spontaneous, consistent, rhythmic anal contractions, taking the form of “plateaus” with multiple twitches (peaks) in each pressure wave. These basal contractions were very heterogeneous; their frequency was 0.91-4.17 per min (mean 1.6980, SD 0.57698), their mean duration was 26.67 s and mean number of peaks was 12.53. Our morphological assessment revealed that with the aforementioned surgical procedure, both sphincters were completely sectioned. In manometry, the described activity disappeared and was replaced by a gentle oscillation of basal line, without a recognizable pattern. Surprisingly, these findings appeared irrespective of injury repair or not. ASCs survived in this potentially septic area for 7 d, at least. We were able to identify them in 84% of animals, mainly in the muscular section area or in the tissue between the muscular endings. ASCs formed a kind of “conglomerate” in rats treated with injections, while in the biosuture group, they wrapped the suture. ASCs were also able to migrate to the damaged zone. No relevant adverse events or mortality could be related to the stem cells in our study. We also did not find unexpected tissue growths.

CONCLUSION

The proposed procedure produces a consistent sphincter lesion. Biosutures and injections are suitable for cell delivery. ASCs survive and are completely safe in this clinical setting.

Stromal Cell-Derived Factor 1 Plasmid Regenerates Both Smooth and Skeletal Muscle After Anal Sphincter Injury in the Long Term

BACKGROUND

Regenerating muscle at a time remote from injury requires re-expression of cytokines to attract stem cells to start and sustain the process of repair.

OBJECTIVE

We aimed to evaluate the sustainability of muscle regeneration after treatment with a nonviral plasmid expressing stromal cell-derived factor 1.

DESIGN

This was a randomized study.

SETTINGS

The study was conducted with animals in a single research facility.

INTERVENTIONS

Fifty-six female age-/weight-matched Sprague-Dawley rats underwent excision of the ventral half of the anal sphincter complex. Three weeks later, rats were randomly allocated (n = 8) to one of the following groups: no treatment, 100 μg of plasmid encoding stromal cell-derived factor 1 injected locally, local injection of plasmid and 8 × 10 bone marrow-derived mesenchymal stem cells, and plasmid encoding stromal cell-derived factor 1 injected locally with injection of a gelatin scaffold mixed with bone marrow-derived mesenchymal stem cells.

MAIN OUTCOME MEASURES

Anal manometry, histology, immunohistochemistrym and morphometry were performed 8 weeks after treatment. Protein expression of cytokines CXCR4 and Myf5 was investigated 1 week after treatment (n = 6 per group). ANOVA was used, with p < 0.0083 indicating significant differences for anal manometry and p < 0.05 for all other statistical analysis.

RESULTS

Eight weeks after treatment, all of the groups receiving the plasmid had significantly higher anal pressures than controls and more organized muscle architecture in the region of the defect. Animals receiving plasmid alone had significantly greater muscle in the defect (p = 0.03) than either animals with injury alone (p = 0.02) or those receiving the plasmid, cells, and scaffold (p = 0.03). Both smooth and skeletal muscles were regenerated significantly more after plasmid treatment. There were no significant differences in the protein levels of CXCR4 or Myf5.

LIMITATIONS

The study was limited by its small sample size and because stromal cell-derived factor 1 was not blocked.

CONCLUSIONS

A plasmid expressing stromal cell-derived factor 1 may be sufficient to repair an injured anal sphincter even long after the injury and in the absence of mesenchymal stem cell or scaffold treatments. See Video Abstract at http://links.lww.com/DCR/A451.

Systematic Review of Animal Models Used in Research of Origins and Treatments of Fecal Incontinence

BACKGROUND

Fecal incontinence is a common disorder, but its pathophysiology is not completely understood.

OBJECTIVE

The aim of this review is to present animal models that have a place in the study of fecal incontinence.

DATA SOURCES

A literature review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines performed in August 2016 revealed 50 articles of interest. Search terms included fecal/faecal incontinence and animal model or specific species.

STUDY SELECTION

Articles not describing an animal model, in vitro studies, veterinary literature, reviews, and non-English articles were excluded.

MAIN OUTCOME MEASURES

The articles described models in rats (n = 31), dogs (n = 8), rabbits (n = 7), and pigs (n = 4).

RESULTS

Different fecal incontinence etiologies were modeled, including anal sphincter lesions (33 articles) ranging from a single anal sphincter cut to destruction of 50% of the anal sphincter by sharp dissection, electrocautery, or diathermy. Neuropathic fecal incontinence (12 articles) was achieved by complete or incomplete pudendal, pelvic, or inferior rectal nerve damage. Mixed fecal incontinence (5 articles) was modeled either by the inflation of pelvic balloons or an array of several lesions including nervous and muscular damage. Anal fistulas (2 articles), anal sphincter resection (3 articles), and diabetic neuropathy (2 articles) were studied to a lesser extent.

LIMITATIONS

Bias may have arisen from the authors' own work on fecal incontinence and the absence of blinding to the origins of articles.

CONCLUSIONS

Validated animal models representing the main etiologies of fecal incontinence exist, but no animal model to date represents the whole pathophysiology of fecal incontinence. Therefore, the individual research questions still dictate the choice of model and species.

Local injection of bone marrow progenitor cells for the treatment of anal sphincter injury: in-vitro expanded versus minimally-manipulated cells

Background

Anal incontinence is a disabling condition that adversely affects the quality of life of a large number of patients, mainly with anal sphincter lesions. In a previous experimental work, in-vitro expanded bone marrow (BM)-derived mesenchymal stem cells (MSC) were demonstrated to enhance sphincter healing after injury and primary repair in a rat preclinical model. In the present article we investigated whether unexpanded BM mononuclear cells (MNC) may also be effective.

Methods

Thirty-two rats, divided into groups, underwent sphincterotomy and repair (SR) with primary suture of anal sphincters plus intrasphincteric injection of saline (CTR), or of in-vitro expanded MSC, or of minimally manipulated MNC; moreover, the fourth group underwent sham operation. At day 30, histologic, morphometric, in-vitro contractility, and functional analysis were performed.

Results

Treatment with both MSC and MNC improved muscle regeneration and increased contractile function of anal sphincters after SR compared with CTR (p < 0.05). No significant difference was observed between the two BM stem cell types used. GFP-positive cells (MSC and MNC) remained in the proximity of the lesion site up to 30 days post injection.

Conclusions

In the present study we demonstrated in a preclinical model that minimally manipulated BM-MNC were as effective as in-vitro expanded MSC for the recovery of anal sphincter injury followed by primary sphincter repair. These results may serve as a basis for improving clinical applications of stem cell therapy in human anal incontinence treatment.

Regenerative medicine provides alternative strategies for the treatment of anal incontinence

INTRODUCTION AND HYPOTHESIS

Anal incontinence is a common disorder but current treatment modalities are not ideal and the development of new treatments is needed. The aim of this review was to identify the existing knowledge of regenerative medicine strategies in the form of cellular therapies or bioengineering as a treatment for anal incontinence caused by anal sphincter defects.

METHODS

PubMed was searched for preclinical and clinical studies in English published from January 2005 to January 2016.

RESULTS

Animal studies have demonstrated that cellular therapy in the form of local injections of culture-expanded skeletal myogenic cells stimulates repair of both acute and 2 - 4-week-old anal sphincter injuries. The results from a small clinical trial with ten patients and a case report support the preclinical findings. Animal studies have also demonstrated that local injections of mesenchymal stem cells stimulate repair of sphincter injuries, and a complex bioengineering strategy for creation and implantation of an intrinsically innervated internal anal sphincter construct has been successfully developed in a series of animal studies.

CONCLUSION

Cellular therapies with myogenic cells and mesenchymal stem cells and the use of bioengineering technology to create an anal sphincter are new potential strategies to treat anal incontinence caused by anal sphincter defects, but the clinical evidence is extremely limited. The use of culture-expanded autologous skeletal myogenic cells has been most intensively investigated and several clinical trials were ongoing at the time of this report. The cost-effectiveness of such a therapy is an issue and muscle fragmentation is suggested as a simple alternative.

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

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

Treatment of faecal incontinence using allogeneic-adipose-derived mesenchymal stem cells: a study protocol for a pilot randomised controlled trial

INTRODUCTION

Faecal incontinence is a distressing condition with recurrent uncontrolled passage of faecal material. Although faecal incontinence may cause psychological depression and social isolation, previous treatments have been limited. Recently, regenerative treatment has been developed using mesenchymal stem cells. Especially, there are possibilities that adipose-tissue-derived stem cells can be effective to treat a degenerated anal sphincter that is causing faecal incontinence. Therefore, this study aimed to investigate the safety and efficacy of using allogeneic-adipose-derived mesenchymal stem cells in the treatment of the anal sphincter of patients with faecal incontinence.

METHODS AND ANALYSIS

This study is a randomised, prospective, dose escalation, placebo-controlled, single-blinded, single-centre trial with two parallel groups. The safety test is performed by an injection of allogeneic-adipose-derived mesenchymal stem cells (ALLO-ASCs) into the anal sphincter with dose escalation (3 × 10(7), 6 × 10(7) and 9 × 10(7) cells, sequentially). After confirming the safety of the stem cells, an efficacy test is performed by this dose in the experimental group. The experimental group will receive ALLO-ASCs mixed with fibrin glue into the anal sphincter, and the placebo group will receive 0.9% normal saline injection mixed with fibrin glue. The primary end point is to assess the safety of ALLO-ASCs after the injection into the anal sphincter, and the secondary end point is to compare the efficacy of ALLO-ASC injection with fibrin glue in patients with faecal incontinence.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ministry of Food and Drug Safety and the Ministry of Health & Welfare, in the Republic of Korea. The informed consent form was approved by the institutional review board of Gangnam Severance Hospital (IRB approval number 3-2014-0271). Dissemination of the results will be presented at a conference and in peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT02384499; Pre-results.

Faecal incontinence: Current knowledges and perspectives

Faecal incontinence (FI) is a disabling and frequent symptom since its prevalence can vary between 5% and 15% of the general population. It has a particular negative impact on quality of life. Many tools are currently available for the treatment of FI, from conservative measures to invasive surgical treatments. The conservative treatment may be dietetic measures, various pharmacological agents, anorectal rehabilitation, posterior tibial nerve stimulation, and transanal irrigation. If needed, patients may have miniinvasive approaches such as sacral nerve modulation or antegrade irrigation. In some cases, a surgical treatment is proposed, mainly external anal sphincter repair. Although these different therapeutic options are available, new techniques are arriving allowing new hopes for the patients. Moreover, most of them are non-invasive such as local application of an α1-adrenoceptor agonist, stem cell injections, rectal injection of botulinum toxin, acupuncture. New more invasive techniques with promising results are also coming such as anal magnetic sphincter and antropylorus transposition. This review reports the main current available treatments of FI and the developing therapeutics tools.

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.

Functional and histological evidence for the targeted therapy using biocompatible polycaprolactone beads and autologous myoblasts in a dog model of fecal incontinence

BACKGROUND

Injection of bulking agents into the anal canal is limited by several factors, including biological resorption, particle migration, and ongoing degradation of the injected bulking agent.

OBJECTIVE

We investigated whether an injection of polycaprolactone beads containing autologous myoblasts could improve sphincter function in a dog model of fecal incontinence.

DESIGN

The control sham surgery group underwent skin incision around the anal sphincter (n = 5). Fecal incontinence was induced by resecting 25% of the posterior internal/external anal sphincter in another 10 dogs. After 1 month of sphincter injury, dogs were then treated with (n = 5) or without (n = 5) polycaprolactone beads containing PKH-26-labeled autologous myoblasts.

SETTING

This study was conducted at the department of surgery in collaboration with the department of advanced materials.

OUTCOME MEASURES

Three months after injection treatment, the resting and contractile pressure differences of the anal sphincter were compared, and histopathological studies were performed.

RESULTS

The anal pressures in untreated dogs were significantly lower than those in the sham surgery group (p < 0.05). The resting and contractile pressure differences were higher in treated dogs than in untreated dogs (resting pressure difference: 0.7 ± 0.5 vs -0.6 ± 0.8 mmHg; coefficient of the difference in recovery rate, 0.38; 95% CI, 0.15-0.61, p = 0.001; contractile pressure difference: 1.1 ± 4.2 vs -3.9 ± 2.6 mmHg; coefficient, 1.63; 95% CI, 0.55-2.71, p = 0.003). Immunofluorescent staining confirmed that the myoblasts had differentiated and synthesized myosin heavy chain, as observed in vitro.

LIMITATIONS

This study was limited by the lack of comparison of injecting beads containing autologous myoblasts with injecting myoblasts alone.

CONCLUSION

This study shows that an injection of polycaprolactone beads containing autologous myoblasts may improve anal sphincter function in an animal model of fecal incontinence.

Coadministration of basic fibroblast growth factor-loaded polycaprolactone beads and autologous myoblasts in a dog model of fecal incontinence

PURPOSE

Basic fibroblastic growth factor (bFGF), a member of the heparin-binding growth factor family, regulates muscle differentiation. We investigated whether coadministration of autologous myoblasts and bFGF-loaded polycaprolactone beads could improve sphincter recovery in a dog model of fecal incontinence (FI).

METHODS

FI was induced by resecting 25% of the posterior anal sphincter in ten mongrel dogs. One month later, the dogs were randomized to receive either PKH-26-labeled autologous myoblasts alone (M group, five dogs) or autologous myoblasts and bFGF-loaded polycaprolactone beads (MBG group, five dogs). The outcomes included anal manometry, compound muscle action potentials (CMAPs) of the pudendal nerve, and histology.

RESULTS

The increase in anal contractile pressure over 3 months was significantly greater in the MBG group (from 4.85 to 6.83 mmHg) than that in the M group (from 4.94 to 4.25 mmHg), with a coefficient for the difference in recovery rate of 2.672 (95% confidence interval [CI] 0.962 to 4.373, p = 0.002). The change in the CMAP amplitude was also significantly greater in the MBG group (from 0.59 to 1.56 mV) than that in the M group (from 0.81 to 0.67 mV) (coefficient 1.114, 95% CI 0.43 to 1.80, p = 0.001). Labeled cells were detected in 2/5 (40%) and 5/5 (100%) dogs in the M and MBG groups, respectively.

CONCLUSION

Coadministration of bFGF-loaded PCL beads and autologous myoblasts improved the recovery of sphincter function in a dog model of FI and had better outcomes than cell-based therapy alone.

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.

The future of research in female pelvic medicine

Female pelvic medicine and reconstructive surgery (FPMRS) was recently recognized as a subspecialty by the American Board of Medical Specialties (ABMS). FPMRS treats female pelvic disorders (FPD) including pelvic organ prolapse (POP), urinary incontinence (UI), fecal incontinence (FI), lower urinary tract symptoms (LUTS), lower urinary tract infections (UTI), pelvic pain, and female sexual dysfunction (FSD). These conditions affect large numbers of individuals, resulting in significant patient, societal, medical, and financial burdens. Given that treatments utilize both medical and surgical approaches, areas of research in FPD necessarily cover a gamut of topics, ranging from mechanistically driven basic science research to randomized controlled trials. While basic science research is slow to impact clinical care, transformational changes in a field occur through basic investigations. On the other hand, clinical research yields incremental changes to clinical care. Basic research intends to change understanding whereas clinical research intends to change practice. However, the best approach is to incorporate both basic and clinical research into a translational program which makes new discoveries and effects positive changes to clinical practice. This review examines current research in FPD, with focus on translational potential, and ponders the future of FPD research. With a goal of improving the care and outcomes in patients with FPD, a strategic collaboration of stakeholders (patients, advocacy groups, physicians, researchers, professional medical associations, legislators, governmental biomedical research agencies, pharmaceutical companies, and medical device companies) is an absolute requirement in order to generate funding needed for FPD translational research.

A novel animal model for external anal sphincter insufficiency

PURPOSE

Reliable animal models are essential to evaluate future therapeutic options like cell-based therapies for external anal sphincter insufficiency. The goal of our study was to describe the most reliable model for external sphincter muscle insufficiency by comparing three different methods to create sphincter muscle damage.

METHODS

In an experimental animal study, female Lewis rats (200-250 g) were randomly assigned to three treatment groups (n = 5, each group). The external sphincter muscle was weakened in the left dorsal quadrant by microsurgical excision, cryosurgery, or electrocoagulation by diathermy. Functional evaluation included in vivo measurements of resting pressure, spontaneous muscle contraction, and contraction in response to electrical stimulation of the afferent nerve at baseline and at 2, 4, and 6 weeks after sphincter injury. Masson's trichrome staining and immunofluorescence for skeletal muscle markers was performed for morphological analysis.

RESULTS

Peak contraction after electrical stimulation was significantly decreased after sphincter injury in all groups. Contraction forces recovered partially after cryosurgery and electrocoagulation but not after microsurgical excision. Morphological analysis revealed an incomplete destruction of the external sphincter muscle in the cryosurgery and electrocoagulation groups compared to the microsurgery group.

CONCLUSIONS

For the first time, three different models of external sphincter muscle insufficiency were directly compared. The animal model using microsurgical sphincter destruction offers the highest level of consistency regarding tissue damage and sphincter insufficiency, and therefore represents the most reliable model to evaluate future therapeutic options. In addition, this study represents a novel model to specifically test the external sphincter muscle function.

Effect of myogenic stem cells on the integrity and histomorphology of repaired transected external anal sphincter

INTRODUCTION AND HYPOTHESIS

The objective was to evaluate the effect of myogenic stem cells on histological properties and the volume of striated muscle of the external anal sphincter after transection and repair.

METHODS

Histological analysis was performed on the external anal sphincters of 40 young female rats euthanized at 7 or 90 days after transection and repair and randomization to injection of either phosphate buffered solution (PBS) or myogenic stem cells (SC) at the transection site. Sphincter complexes, previously evaluated for neurophysiological function, were processed for histology and analyzed for possible disruption, amount of inflammation, and volume of striated muscle. The relationship between the muscular disruption and contractile force of sphincters was evaluated.

RESULTS

Disruption was seen in 100 % of sphincters 7 days after repair for both SC and control animals. Eighty-nine percent of controls and 78% of SC-administered animals had intact sphincters at 90 days. Significant inflammatory infiltrate was seen in repaired anal sphincters for both the PBS and the SC groups at 7 days, and persisted at 90 days, with no difference between treatment groups. Striated muscle volume increased from 7 to 90 days for both control and SC-administered animals. Although there was no difference in volume between treatments, there was substantial temporal improvement in contractile force generation of the sphincters receiving SC compared with those receiving PBS.

CONCLUSION

In this animal model, administration of myogenic stem cells to transected/repaired anal sphincters did not alter the amount of inflammation nor the volume of striated muscle, suggesting that stem cells might improve contractile function through other cellular processes.

The effect of age and medical comorbidities on in vitro myoblast expansion in women with and without pelvic organ prolapse

INTRODUCTION

This is an observational study is designed to assess the influence of age, prolapse and medical co-morbidities on myogenic stem cells growth in-vitro.

METHODS

A biopsy of the rectus abdominus muscle was obtained during surgery in patients with and without pelvic organ prolapse (POP). Nuclei number and fiber count were correlated with patient's age, presence of POP, and medical comorbidities. Efficiency of expansion of myogenic stem cells in vitro was calculated. The percentage of Pax7-, MyoD-, and desmin-positive cells was correlated with age, POP status, and medical comorbidities.

RESULTS

A total of 17 specimens were obtained; 13 specimens were available for histologic analysis. There was no correlation between patient's age, POP status or medical comorbidities and nuclei or fiber count, growth rate, or the percentage of Pax7- and MyoD-positive cells. Patients with 2 to 4 medical comorbidities were noted to have a significantly lower percentage of desmin-positive cells. Specimens with a higher nuclear count had significantly better cellular expansion. Data were analyzed using Kruskal-Wallis or Wilcoxon rank sum statistics.

CONCLUSIONS

Multiple medical comorbidities but not patient's age or POP status influenced in vitro myogenic stem cell growth. These data suggest that patients with advancing age or POP may be acceptable autologous donors if treatment of urinary or anal incontinence requires myoblast transplantation.

Myoblast differentiation on growth factor-immobilized polycaprolactone microparticles: a potential bioactive bulking agent for fecal incontinence

Fecal incontinence (FI), caused by damage or weakness of the anal sphincter, is a devastating problem for patients experiencing the symptom. Although injectable bulking agents are accepted as a minimally invasive therapeutic technique to treat FI, their short-term efficacy and inability to enhance the anal sphincter function are considered as challenges in clinical practices. In this study, growth factor [nerve growth factor (NGF) and/or basic fibroblast growth factor (bFGF)]-immobilized polycaprolactone (PCL) microparticles were prepared as an injectable bioactive bulking agent that can provide a bulking effect (by microparticles) and stimulate myoblast differentiation or injured muscles around the anus (by the sustained release of growth factors) to enhance the sphincter function for the effective treatment of FI. Pluronic F127-entrapped PCL microparticles were prepared by an isolated particle-melting method. Two different growth factors (NGF and bFGF) were incorporated on the surfaces of the Pluronic F127-entrapped PCL microparticles via heparin binding. The growth factors immobilized on the microparticles were released in a sustained manner over 4 weeks. From cell cultures on the growth factor-immobilized microparticles, it was observed that the myoblasts adhered on the microparticle surfaces showed differences in differentiation into myotubes depending on the growth factor type. In particular, the dual NGF/bFGF-immobilized microparticle group was effective for myogenic differentiation in comparison with the single growth factor (NGF or bFGF)-immobilized groups. The dual NGF/bFGF-immobilized microparticles are suitable to be applied as an injectable bulking agent for the treatment of FI.

Tissue engineering in the gut: developments in neuromusculature

The complexity of the gastrointestinal (GI) tract lies in its anatomy as well as in its physiology. Several different cell types populate the GI tract, adding to the complexity of cell sourcing for regenerative medicine. Each cell layer has a specialized function in mediating digestion, absorption, secretion, motility, and excretion. Tissue engineering and regenerative medicine aim to regenerate the specific layers mimicking architecture and recapitulating function. Gastrointestinal motility is the underlying program that mediates the diverse functions of the intestines, as an organ. Hence, the first logical step in GI regenerative medicine is the reconstruction of the tubular smooth musculature along with the drivers of their input, the enteric nervous system. Recent advances in the field of GI tissue engineering have focused on the use of scaffolding biomaterials in combination with cells and bioactive factors. The ability to innervate the bioengineered muscle is a critical step to ensure proper functionality. Finally, in vivo studies are essential to evaluate implant integration with host tissue, survival, and functionality. In this review, we focus on the tubular structure of the GI tract, tools for innervation, and, finally, evaluation of in vivo strategies for GI replacements.

Functional outcome after anal sphincter injury and treatment with mesenchymal stem cells

This research demonstrates the regenerative effects of mesenchymal stem cells (MSCs) on the injured anal sphincter by comparing anal sphincter pressures following intramuscular and serial intravascular MSC infusion in a rat model of anal sphincter injury. Fifty rats were divided into injury (n = 35) and no injury (NI; n = 15) groups. Each group was further divided into i.m., serial i.v., or no-treatment (n = 5) groups and followed for 5 weeks. The injury consisted of an excision of 25% of the anal sphincter complex. Twenty-four hours after injury, 5 × 10(5) green fluorescent protein-labeled MSCs in 0.2 ml of phosphate-buffered saline (PBS) or PBS alone (sham) were injected into the anal sphincter for i.m. treatment; i.v. and sham i.v. treatments were delivered daily for 6 consecutive days via the tail vein. Anal pressures were recorded before injury and 10 days and 5 weeks after treatment. Ten days after i.m. MSC treatment, resting and peak pressures were significantly increased compared with those in sham i.m. treatment (p < .001). When compared with the NI group, the injury groups had anal pressures that were not significantly different 5 weeks after i.m./i.v. treatment. Both resting and peak pressures were also significantly increased after i.m./i.v. MSC treatment compared with treatment with PBS (p < .001), suggesting recovery. Statistical analysis was done using paired t test with Bonferroni correction. Marked decrease in fibrosis and scar tissue was seen in both MSC-treated groups. Both i.m. and i.v. MSC treatment after injury caused an increase in anal pressures sustained at 5 weeks, although fewer cells were injected i.m. The MSC-treated groups showed less scarring than the PBS-treated groups, with the i.v. infusion group showing the least scarring.

Emerging surgical therapies for faecal incontinence

Faecal incontinence is a common condition and is associated with considerable morbidity and economic cost. The majority of patients are managed with conservative interventions. However, for those patients with severe or refractory incontinence, surgical treatment might be required. Over the past 20 years, numerous developments have been made in the surgical therapies available to treat such patients. These surgical therapies can be classified as techniques of neuromodulation, neosphincter creation (muscle or artificial) and injection therapy. Techniques of neuromodulation, particularly sacral nerve stimulation, have transformed the management of these patients with a minimally invasive procedure that offers good results and low morbidity. By contrast, neosphincter procedures are characterized by being more invasive and associated with considerable morbidity, although some patients will experience substantial improvements in their continence. Injection of bulking agents into the anal canal can improve symptoms and quality of life in patients with mild-to-moderate incontinence, and the use of autologous myoblasts might be a future therapy. Further research and development is required not only in terms of the devices and procedures, but also to identify which patients are likely to benefit most from such interventions.

Surgical therapies for fecal incontinence

PURPOSE OF REVIEW

Fecal incontinence is a significant source of morbidity and decreased quality of life (QOL) for many. Until recent years, few therapies beyond medical management were available for patients. Surgical treatment of fecal incontinence has evolved from colostomy and direct repair of muscle defects to interventional techniques such as nerve stimulation and bulking agents. We review the most recent surgical options for the treatment of fecal incontinence within the context of established therapies.

RECENT FINDINGS

Overlapping sphincteroplasty is an established therapy that improves continence and QOL, although results deteriorate over time. Implanted artificial bowel sphincter has a 100% complication rate and 80% are explanted over time. Sacral nerve stimulation has minimal risk and more durable long-term improvement in continence. Less invasive versions of nerve stimulation are being researched. Injectable biomaterials have shown some promise, although durability of results is not clear. Novel therapies, including muscle cell transfer and pelvic slings are currently being investigated.

SUMMARY

Surgical therapies for fecal incontinence continue to evolve and show promise in improving QOL with a lower risk profile. Effective valuation of these therapies is currently limited by heterogeneous studies, short duration of follow up, and inconsistent outcome measures.

Safety assessment of myogenic stem cell transplantation and resulting tumor formation

OBJECTIVES

To assess for stem cell migration to liver and lung after transplantation in injured rat anal sphincters. To evaluate histological findings of unanticipated ectopic foci of growth.

METHODS

This is a prospective study involving 33 female virginal Sprague-Dawley rats. Anal sphincters were transected and repaired under sterile technique. Animals received injections of 5.0 × 10 myogenic stem cells (24 rats) or sham control (9 rats) and were killed on day 30. Liver and lung samples were obtained. Upon encountering abnormal foci of growth, further staining protocols were employed. Enzyme-linked immunosorbent assay studies evaluated stem cell media for in vitro growth factor secretion.

RESULTS

No evidence of cell migration to liver or lung was found at the time of euthanasia in any study animal. Ectopic foci of growth were noted in 2 transplant rats. Further histological evaluations of these growths were consistent with benign tumors: no nuclear abnormalities and no evidence of proliferation at day 30. Enzyme-linked immunosorbent assay studies demonstrated positive secretion of vascular endothelial growth factor and insulin growth factor into the media of cultured rat myogenic stem cells.

CONCLUSIONS

Whereas distant migration was not encountered in the liver or lung, 2 transplanted rats developed abnormal foci of growth, that is, tumors, from the external anal sphincter-raising further safety questions. Additional evaluation of these foci seemed benign. Possible explanations include cell trapping, stem cell overgrowth, and/or paracrine factors. The lack of cell migration supports that future investigation of safety parameters could focus locally.

In vivo recovery of the injured anal sphincter after repair and injection of myogenic stem cells: an experimental model

OBJECTIVE

This study aims to evaluate in vivo function of the external anal sphincter after transection and repair augmented with myogenic stem cells, and to establish normative electromyography parameters of the rodent external anal sphincter.

DESIGN AND SETTING

Thirty-three Sprague-Dawley rodents underwent baseline needle electromyography of the external anal sphincter. Motor unit action potentials were obtained and normative parameters established. Animals were randomly assigned to a myogenic stem cell group (n = 24) or control group (n = 9). All underwent proctoepisiotomy. The control group underwent layered repair with phosphate-buffered saline injection to the external anal sphincter. The treatment group underwent identical repair with injection of myogenic stem cells 5.0 × 10. Baseline anal pressure recordings were collected and repeated 2 weeks postintervention, and electromyography was repeated at 2 and 4 weeks. Groups were compared across 3 time points with the use of repeated measures ANOVA.

MAIN OUTCOME MEASURES

The primary outcomes measured were the functional recovery of rat anal sphincters after stem cell transplantation as assessed by objective electromyography and anal pressure measures.

RESULTS

A mean of 17 motor unit action potentials were sampled per animal. At 2 weeks postrepair, there was a significant difference between control and transplant groups with respect to amplitude, duration, turns, and phases (p < 0.01 for each). No significant electromyography differences were seen at 4 weeks. Resting and peak anal pressures declined significantly at 2 weeks postinjury in the control but not in the stem cell group.

LIMITATIONS

Use of a murine animal population limited the subjective feedback and wider applicability.

CONCLUSIONS

In vivo functional studies show recovery of anal sphincter pressures and electromyography to preinjury levels by day 14 in the myogenic stem cell group but not controls. At 4 weeks, all electromyography parameters returned to baseline irrespective of group. Restoration of function may be accelerated by the transplantation of myogenic stem cells and associated trophic factors.

Restoration of anal sphincter function after myoblast cell therapy in incontinent rats

Fecal incontinence (FI) remains a socially isolating condition with profound impact on quality of life for which autologous myoblast cell therapy represents an attractive treatment option. We developed an animal model of FI and investigated the possibility of improving sphincter function by intrasphincteric injection of syngeneic myoblasts. Several types of anal cryoinjuries were evaluated on anesthetized Fischer rats receiving analgesics. The minimal lesion yielding sustainable anal sphincter deficiency was a 90° cryoinjury of the sphincter, repeated after a 24-h interval. Anal sphincter pressure was evaluated longitudinally by anorectal manometry under local electrostimulation. Myoblasts were prepared using a protocol mimicking a clinical-grade process and further transduced with a GFP-encoding lentiviral vector before intrasphincteric injection. Experimental groups were uninjured controls, cryoinjured + PBS, and cryoinjured + myoblasts (different doses or injection site). Myoblast injection was well tolerated. Transferred myoblasts expressing GFP integrated into the sphincter and differentiated in situ into dystrophin-positive mature myofibers. Posttreatment sphincter pressures increased over time. At day 60, pressures in the treated group were significantly higher than those of PBS-injected controls and not significantly different from those of normal rats. Longitudinal follow-up showed stability of the therapeutic effect on sphincter function over a period of 6 months. Intrasphincteric myoblast injections at the lesion borders were equally as effective as intralesion administration, but an injection opposite to the lesion was not. These results provide proof of principle for myoblast cell therapy to treat FI in a rat model. This strategy is currently being evaluated in humans in a randomized double-blind placebo-controlled clinical trial.

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.

Injection of porous polycaprolactone beads containing autologous myoblasts in a dog model of fecal incontinence

PURPOSE

Few studies have examined whether bioengineering can improve fecal incontinence. This study designed to determine whether injection of porous polycaprolactone beads containing autologous myoblasts improves sphincter function in a dog model of fecal incontinence.

METHODS

The anal sphincter of dogs was injured and the dogs were observed without and with (n = 5) the injection of porous polycaprolactone beads containing autologous myoblasts into the site of injury. Autologous myoblasts purified from the gastrocnemius muscles were transferred to the beads. Compound muscle action potentials (CMAP) of the pudendal nerve, anal sphincter pressure, and histopathology were determined 3 months after treatment.

RESULTS

The amplitudes of the CMAP in the injured sphincter were significantly lower than those measured before injury (1.22 mV vs. 3.00 mV, P = 0.04). The amplitudes were not different between dogs with and without the injection of autologous myoblast beads (P = 0.49). Resting and squeezing pressures were higher in dogs treated with autologous myoblast beads (2.00 mmHg vs. 1.80 mmHg; 6.13 mmHg vs. 4.02 mmHg), although these differences were not significant in analyses of covariance adjusted for baseline values. The injection site was stained for smooth muscle actin, but showed evidence of foreign body inflammatory reactions.

CONCLUSION

This was the first study to examine whether bioengineering could improve fecal incontinence. Although the results did not show definite evidence that injection of autologous myoblast beads improves sphincter function, we found that the dog model was suitable and reliable for studying the effects of a potential treatment modality for fecal incontinence.

Mesenchymal stem cells can improve anal pressures after anal sphincter injury

OBJECTIVE

Fecal incontinence reduces the quality of life of many women but has no long-term cure. Research on mesenchymal stem cell (MSC)-based therapies has shown promising results. The primary aim of this study was to evaluate functional recovery after treatment with MSCs in two animal models of anal sphincter injury.

METHODS

Seventy virgin female rats received a sphincterotomy (SP) to model episiotomy, a pudendal nerve crush (PNC) to model the nerve injuries of childbirth, a sham SP, or a sham PNC. Anal sphincter pressures and electromyography (EMG) were recorded after injury but before treatment and 10 days after injury. Twenty-four hours after injury, each animal received either 0.2 ml saline or 2 million MSCs labelled with green fluorescing protein (GFP) suspended in 0.2 ml saline, either intravenously (IV) into the tail vein or intramuscularly (IM) into the anal sphincter.

RESULTS

MSCs delivered IV after SP resulted in a significant increase in resting anal sphincter pressure and peak pressure, as well as anal sphincter EMG amplitude and frequency 10 days after injury. MSCs delivered IM after SP resulted in a significant increase in resting anal sphincter pressure and anal sphincter EMG frequency but not amplitude. There was no improvement in anal sphincter pressure or EMG with in animals receiving MSCs after PNC. GFP-labelled cells were not found near the external anal sphincter in MSC-treated animals after SP.

CONCLUSION

MSC treatment resulted in significant improvement in anal pressures after SP but not after PNC, suggesting that MSCs could be utilized to facilitate recovery after anal sphincter injury.

Effect of human muscle-derived stem cells on cryoinjured mouse bladder contractility

OBJECTIVE

To investigate the effect of human muscle-derived stem cells (hMDSCs) on ameliorating impaired detrusor contractility in a cryoinjured bladder murine model.

METHODS

The hMDSCs were isolated and cultured by modified preplate technique, and only CD34-positive hMDSCs were extracted by Mini-MACS kits. Isolated hMDSCs were prelabeled with PKH26 and injected into the cryoinjured bladder to observe the pattern and characteristics. The nude mice were subdivided into three groups: normal group (N), cryoinjury bladder group with saline injection (C), and hMDSCs injection group after cryoinjury (M). At 2 weeks after injecting hMDSCs, we compared the contractility of bladder muscle strip stimulated by electrical field stimulation (EFS), acetylcholine (Ach.), and adenosine triphosphate (ATP), and the bladder smooth muscle tissue was examined by immunohistochemistry.

RESULTS

The contractile powers of bladder muscle strip in the C group were more decreased than the N group after EFS, Ach, and ATP treatment (P < .05). The bladder contractility of the M group was more increased than in the C group (P < .05), but was lower than the N group after EFS and Ach treatment. However, there was no significant difference of contractile power between the C and M groups after ATP stimulation. In immunohistochemical staining, the thickness of the bladder smooth muscle layer in the M group was significantly increased compared with the C group, and PKH26-labeled implanted cells were positive for smooth muscle cell differentiation marker (α-SMA) in the injected region.

CONCLUSION

hMDSCs injection increased cholinergic bladder contractile power but not the purinergic component of bladder contraction after cryoinjury.

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.

Recovery of the injured external anal sphincter after injection of local or intravenous mesenchymal stem cells

OBJECTIVES

To understand the endogenous process of wound healing after anal sphincter injury and to determine possible mechanisms by which mesenchymal stem cells (MSCs) exert their regenerative potential.

METHODS

Virginal female rats (n=204) underwent anal sphincter laceration and repair. Thereafter, animals were randomly assigned to control injection, injection with intravenous MSCs, or direct injection of MSCs into the injured sphincter. Twenty uninjured animals served as baseline controls. Sphincters were analyzed for contractile function and parameters of wound healing 24 hours, 48 hours, 7 days, and 21 days after injury.

RESULTS

Direct injection of MSCs into the injured anal sphincter resulted in improved contractile function 21 days after injury compared with controls. Although expression of both proinflammatory (cyclooxygenase-2 and interleukin-6) and anti-inflammatory (interleukin-10 and tumor necrosis factor-α-stimulated gene-6) genes were increased dramatically and transiently after injury, MSCs did not alter this response. In contrast, transforming growth factor (TFG)-β1 (an important mediator of matrix deposition by mesenchymal cells) and lysyl oxidase (an enzyme important for synthesis of collagen and elastin) expression increased dramatically at earlier time points in the direct MSC injection group compared with controls. Increased expression of TFG-β1 and lysyl oxidase in directly injected sphincters was associated with increased collagen deposition and engraftment of MSCs in the sphincter.

CONCLUSION

In this preclinical animal model, direct, but not intravenous, injection of MSCs into the injured anal sphincter at the time of repair resulted in improved contractile function of the sphincter after injury, increased matrix deposition in the external anal sphincter, and increased expression of TFG-β1 and lysyl oxidase in the acute phase after injury.

Protective effect of sodium ascorbate on efficacy of intramuscular transplantation of autologous muscle-derived cells

INTRODUCTION

The possible reason for elimination of myogenic cells after transplantation is inflammation at the injection site associated with oxidative stress. The aim of this study was to determine whether preconditioning of muscle-derived cells with an antioxidant, sodium ascorbate, can influence the fate of transplanted cells.

METHODS

Autologous transplantation of muscle-derived cells was performed in rabbits. Isolated cells were identified, lipofected with β-galactosidase, preincubated or not with sodium ascorbate, and injected intramuscularly.

RESULTS

Two weeks after autologous transplantation in the edge of a previous muscle defect, donor cells formed multinucleated young myotubes. Pretreatment of cells with sodium ascorbate before injection resulted in a significant increase of donor cells at the injection site 2 weeks after transfer.

CONCLUSIONS

These results show that: (1) preincubation with antioxidant can increase the efficacy of myogenic cell transplantation; and (2) oxidative stress may play a role in elimination of cells after autologous transplantation.