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

Experimental evaluation of an artificial anal sphincter based on biomechanical compatibility

BACKGROUND

The artificial anal sphincter is a device used to treat patients with fecal incontinence who are unable to control their bowel movements on their own. Long-term morphological changes in the tissue surrounding the artificial anal sphincter can cause biomechanical compatibility problems, which seriously affect the clinical application of the artificial anal sphincter.

METHODS

In this paper, the superelasticity of shape memory alloys was utilized to design and fabricate a biomechanically compatible constant force clamping artificial anal sphincter. An in vitro simulation system was constructed to verify the effectiveness, safety, and constant force characteristics of the artificial anal sphincter.

RESULTS

The experimental results demonstrated that the artificial anal sphincter could be effectively closed with no leakage of the liquid-like intestinal contents, which are most likely to leak. The pressure of the artificial anal sphincter on the intestinal tube gradually increased and eventually became constant during closure, and the pressure value was always less than the intestinal blood supply pressure threshold.

CONCLUSIONS

In this paper, we designed an artificial anal sphincter based on biomechanical compatibility and the corresponding in vitro simulation experimental program and preliminarily verified the effectiveness, safety, and constant force characteristics of the artificial anal sphincter.

3D spheroids versus 2D-cultured human adipose stem cells to generate smooth muscle cells in an internal anal sphincter-targeting cryoinjured mouse model

BACKGROUND

The efficacy of cell implantation via 3D-spheroids to treat basal tone in fecal incontinence remains unclear. To address this, in this study, we aimed to identify cell differentiation and assess the development of a contractile phenotype corresponding to smooth muscle cells (SMCs) following implantation of 3D-spheroid and 2D-cultured human adipose stem cells (hASCs) in an in vivo internal anal sphincter (IAS)-targeted mouse model.

METHODS

We developed an IAS-targeted in vivo model via rapid freezing (at - 196 °C) of the dorsal layers of the region of interest (ROI) of the IAS ring posterior quarter, between the submucosal and muscular layers, following submucosal dissection (n = 60 rats). After implantation of tetramethylindocarbocyanine perchlorate (Dil)-stained 3D and 2D-cells into randomly allocated cryoinjured rats, the entire sphincter ring or only the cryoinjured ROI was harvested. Expression of SMC markers, RhoA/ROCKII and its downstream molecules, and fibrosis markers was analyzed. Dil, α-smooth muscle actin (α-SMA), and RhoA signals were used for cell tracking.

RESULTS

In vitro, 3D-spheroids exhibited higher levels of SMC markers and RhoA/ROCKII-downstream molecules than 2D-hASCs. The IAS-targeted cryoinjured model exhibited substantial loss of SMC layers of the squamous epithelium lining of the anal canal, as well as reduced expression of SMC markers and RhoA-related downstream molecules. In vivo, 3D-spheroid implantation induced SMC markers and contractile molecules weakly at 1 week. At 2 weeks, the mRNA expression of aSma, Sm22a, Smoothelin, RhoA, Mypt1, Mlc20, Cpi17, and Pp1cd increased, whereas that of fibrosis markers reduced significantly in the 3D-spheroid implanted group compared to those in the sham, non-implanted, and 2D-hASC implanted groups. Protein levels of RhoA, p-MYPT1, and p-MLC20 were higher in the 3D-spheroid-implanted group than in the other groups. At 2 weeks, in the implanted groups, the cryoinjured tissues (which exhibited Dil, α-SMA, and RhoA signals) were restored, while they remained defective in the sham and non-implanted groups.

CONCLUSIONS

These findings demonstrate that, compared to 2D-cultured hASCs, 3D-spheroids more effectively induce a contractile phenotype that is initially weak but subsequently improves, inducing expression of RhoA/ROCKII-downstream molecules and SMC differentiation associated with IAS basal tone.

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.

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.

Management of urinary and bowel dysfunction in rabbit model of spinal cord injury using Schwann cells and muscle progenitors: functional study and evidence for novel mechanism of action

PURPOSE

We tried to investigate the role of Schwann and satellite cells in the treatment of neurogenic bladder and bowel dysfunction; following spinal cord injury in the rabbit model.

METHODS

Twelve male New Zealand rabbits underwent induction of neurogenic bladder by spinal cord injury. Rabbits underwent the fiber tractography analysis to confirm the induction of spinal cord injury. Then, animals were randomly divided into two groups. In group I (n = 4), Schwann cells were obtained from autologous peroneal nerve. In group II (n = 4), the co-culture of nerve-muscle cells was obtained from autologous peroneal nerve and quadriceps muscle. Animals in the control group (n = 4) did not undergo any rehabilitation therapy. One and 4 months after injection of cells into the external anal sphincter, electromyography, urethral pressure profiles, urodynamic studies, voiding cystourethrogram, and manometry was performed to confirm the efficacy of treatment in short- (1 month) and long-term (4 months) follow-ups.

RESULTS

The investigations validated that no statistically significant difference was detected between the two experimental groups in a short-term follow-up (p-value > 0.05). However, the functional features were improved in group II in long-term follow-up. In both groups, the external anal sphincter contracted in response to electrical signals delivered to the muscle. However, more signals were detected in group II in electromyography evaluation. The immunohistochemical staining demonstrated that the histological features of the bladder and spinal cord were more satisfactory in group II in all follow-ups compared to group I, in terms of less edema, inflammation, presence of progenitor cells, and expression of muscle and nerve markes.

CONCLUSION

Our results suggested that the injection of nerve-muscle co-culture cells into the external anal sphincter may be a helpful tactic for ameliorating the urological complications; following spinal cord injury induction in the rabbit model.

The Artificial Bowel Sphincter in the Treatment of Fecal Incontinence, Long-term Complications

BACKGROUND

Fecal incontinence is a common and debilitating condition, of which the prevalence increases with age. Several medical and minimally invasive treatment modalities are available. However, for patients with greater sphincter defects, these treatments are often not sufficient. For these patients, the artificial bowel sphincter could be an alternative to colostomy. The artificial bowel sphincter has proven to be effective in the short term. Less is known whether the benefits sustain over time.

OBJECTIVE

The aim of this study was to assess the long-term outcome of the artificial bowel sphincter in patients with refractory fecal incontinence.

DESIGN

A retrospective record review was conducted in conjunction with questionnaires.

SETTING

This study was conducted in a tertiary hospital setting.

MAIN OUTCOME MEASURES

The primary end point was any complication. The secondary end point was fecal loss.

PATIENTS

The patients included were adults experiencing severe fecal incontinence treated with artificial bowel sphincter, operated on between 1997 and 2014.

RESULTS

Sixty-three patients were included in this study. After a median follow-up of 57 months (range, 1-198), the device had been explanted in 31 patients (49.2%; 95% CI, 36.5-62.0). In total, 101 reoperations were conducted, ranging from 1 to 6 reoperations per patient. The main reasons for revision were device failure and infection. At 5 years follow-up, 80% of the cohort had experienced a complication requiring surgery. Twenty-two (35%) patients had restored continence.

LIMITATIONS

This study was limited by its retrospective design and subjective secondary outcome.

CONCLUSION

Patients with severe end-stage fecal incontinence can benefit from artificial bowel sphincter, but this requires a large number of reoperations, and at least 20% of patients will eventually have a colostomy. Therefore, careful patient selection and the involvement of patients in decision making regarding the potential benefits and limitations of this technique are paramount. See Video Abstract at http://links.lww.com/DCR/B242. EL ESFÍNTER INTESTINAL ARTIFICIAL EN EL TRATAMIENTO DE LA INCONTINENCIA FECAL, COMPLICACIONES A LARGO PLAZO: La incontinencia fecal es una condición común y debilitante, cuya prevalencia aumenta con la edad. Se encuentran disponibles varias modalidades de tratamiento médico y mínimamente invasivo. Sin embargo, para pacientes con defectos del esfínter mayores, estos tratamientos a menudo no son suficientes. Para estos pacientes, el esfínter intestinal artificial (ABS) podría ser una alternativa a la colostomía. El esfínter intestinal artificial demostró ser efectivo a corto plazo. Se sabe menos si los beneficios se mantienen a lo largo del tiempo.El objetivo de este estudio fue evaluar el resultado a largo plazo del esfínter intestinal artificial en pacientes con incontinencia fecal refractaria.Se realizó una revisión retrospectiva de los registros junto con los cuestionarios.Realizado en un entorno de hospital de tercel nivel.El punto final primario fue cualquier complicación, el punto final secundario fue la pérdida fecal.Los pacientes incluidos fueron adultos que padecían incontinencia fecal severa tratados con esfínter intestinal artificial, operados entre 1997 y 2014.Sesenta y tres pacientes fueron incluidos en este estudio. Después de una mediana de seguimiento de 57 meses (rango 1-198), el dispositivo había sido explantado en 31 pacientes (49.2%; 95CI 36.5-62.0). En total, se realizaron 101 reoperaciones, que oscilaron de una a seis reoperaciones por paciente. Las principales razones para la revisión fueron la falla del dispositivo y la infección. A los cinco años de seguimiento, el 80% de la cohorte había experimentado una complicación que requería cirugía. 22 pacientes habían recuperado la continencia (35%).Diseño retrospectivo y resultado secundario subjetivo.Los pacientes con incontinencia fecal grave en etapa terminal pueden beneficiarse del esfínter intestinal artificial, pero esto requiere una gran cantidad de reoperaciones y al menos el 20% de los pacientes eventualmente tendrán una colostomía. Por lo tanto, la selección cuidadosa del paciente y la participación de los pacientes en la toma de decisiones con respecto a los posibles beneficios y limitaciones de esta técnica es primordial. Consulte Video Resumen en http://links.lww.com/DCR/B242.

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.

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.

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.