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

Current and future state of the management of Hirschsprung disease

The enteric nervous system (ENS) consists of a network of neurons and glia that control numerous complex functions of the gastrointestinal tract. Hirschsprung disease (HSCR) is a congenital disorder characterized by the absence of ENS along variable lengths of distal intestine due to failure of neural crest-derived cells to colonize the distal intestine during embryonic development. A patient with HSCR usually presents with severe constipation in the neonatal period and is diagnosed by rectal suction biopsy, followed by pull-through procedure to surgically remove the affected segment and reconnect the proximal ganglionated intestine to the anus. Outcomes after pull-through surgery are suboptimal and many patients suffer from ongoing issues of dysmotility and bowel dysfunction, suggesting there is room for optimizing the management of this disease. This review focuses on discussing the recent advances to better understand HSCR and leverage them for more accurate and potentially less invasive diagnosis. We also discuss the potential future management of HSCR, particularly cell-based approaches for the treatment of HSCR.

Anorectal malformations

Anorectal malformations (ARM) are rare congenital anomalies with an overall prevalence of 3.32 per 10,000 pregnancies. ARM describe a spectrum of anomalies of the anus and rectum ranging from a minimally displaced anal canal to a complete fusion of the anorectum, vagina and urethra with hypoplastic sphincter and pelvic floor muscle. Aberrant septation of the hindgut with anomalous cloacal membrane during weeks 6 to 9 of gestation form the developmental basis for a spectrum of anomalies defined as ARM. Although underlying specific syndromes and occasional familiar occurrence suggest genetic aetiology, most ARM are non-syndromic and their causal genetic mechanisms and non-genetic insults remain unclear. ARM is a clinical diagnosis, generally made early after birth via careful inspection of the perineum. Prenatal detection remains rare, and modern technical developments have added little to prenatal diagnostics. ARM is corrected surgically. Since its introduction in 1982, posterior sagittal anorectoplasty is the most common surgery for ARM reconstruction. Subsequent surgical adaptations focus on minimizing iatrogenic operative injury by limiting surgical invasiveness. They include laparoscopic procedures and shortening of incisions with confined dissection in open surgery. Although outcomes in patients with ARM have evolved throughout the past decades, there is urgent need for further improvements both in functional outcomes and quality of life. The importance of psychosocial experiences of affected patients is increasingly recognized. Continued research is necessary to improve prenatal detection, to elucidate genetic and epigenetic alterations and to refine optimal surgical procedures.

Tissue engineering and regenerative medicine approaches in colorectal surgery

Tissue engineering and regenerative medicine (TERM) is an emerging field that has provided new therapeutic opportunities by delivering innovative solutions. The development of nontraditional therapies for previously unsolvable diseases and conditions has brought hope and excitement to countless individuals globally. Many regenerative medicine therapies have been developed and delivered to patients clinically. The technology platforms developed in regenerative medicine have been expanded to various medical areas; however, their applications in colorectal surgery remain limited. Applying TERM technologies to engineer biological tissue and organ substitutes may address the current therapeutic challenges and overcome some complications in colorectal surgery, such as inflammatory bowel diseases, short bowel syndrome, and diseases of motility and neuromuscular function. This review provides a comprehensive overview of TERM applications in colorectal surgery, highlighting the current state of the art, including preclinical and clinical studies, current challenges, and future perspectives. This article synthesizes the latest findings, providing a valuable resource for clinicians and researchers aiming to integrate TERM into colorectal surgical practice.

Correction: Balaphas et al. Cell Therapy for Anal Sphincter Incontinence: Where Do We Stand? Cells 2021, 10, 2086

The authors would like to add a new reference to the section "3 [...].

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.

Isolation and Characterization of Stem Cells from the Anal Canal Transition Zone in Pigs

BACKGROUND

Utilization of autologous stem cells has been proposed for the treatment of anal incontinence despite a lack of understanding of their mechanism of action and of the physiological healing process of anal sphincters after injury.

AIMS

We aim to develop a technique allowing isolation and further study of local mesenchymal stem cells, directly from anal canal transition zone in pig.

METHODS

Anal canal was resected "en bloc" from two young pigs and further microdissected. The anal canal transition zone was washed and digested with 0.1% type I collagenase for 45 min at 37 °C. The isolated cells were plated on dishes in mesenchymal stem cell medium and trypsinized when confluent. Cells were further used for flow cytometry analysis and differentiation assays.

RESULTS

The anal canal transition zone localization was confirmed with H&E staining. Following culture, cells exhibited a typical "fibroblast-like" morphology typical of stem cells. Isolated cells were positive for CD90 and CD44 but negative for CD14, CD34, CD45, CD105, CD106, and SLA-DR. Following incubation with specific differentiation medium, isolated cells differentiated into adipocytes, osteoblasts, and chondrocytes, confirming in vitro multipotency.

CONCLUSIONS

Herein, we report for the first time the presence of mesenchymal stem cells in the anal canal transition zone in pigs and the feasibility of their isolation. This preliminary study opens the path to the isolation of human anal canal transition zone mesenchymal stem cells that might be used to study sphincters healing and to treat anal incontinence.

The Effect of Tissue Stromal Vascular Fraction as Compared to Cellular Stromal Vascular Fraction to Treat Anal Sphincter Incontinence

BACKGROUND

The long-term prognosis of current treatments for anal sphincter incontinence (ASI) is poor. Here, we explored the efficacy of tissue adipose stromal vascular fraction SVF (tSVF) on ASI and compared it to that of cellular SVF (cSVF). We then investigated possible mechanisms.

METHODS

Rat cSVF and tSVF were isolated and labeled with DIL. One day after modeling, three groups received phosphate-buffered saline (PBS), cSVF, tSVF, respectively. The control group received nil modeling nor any treatments. The effect was assessed by function test for anal pressure and electromyography, and staining for fiber content, proliferation and differentiation at day 5 and day 10.

RESULTS

cSVF injection resulted in faster healing than tSVF. The cSVF group showed significant improvement on anal pressure on day 10. For the electromyography test, cSVF showed significant improvement for the frequencies on day 10, and for the peak values on both time points, while tSVF showed significant improvement for the peak values on day 10. The two SVF both alleviated fibrosis. Immunofluorescence tracing identified differentiation of some injected cells towards myosatellite cells and smooth muscle cells in both SVF groups. For all the tests, the tSVF group tends to have similar or lower effects than the cSVF group with no significant difference.

CONCLUSION

cSVF and tSVF are both safe and effective in treating ASI, while the effect of cSVF is slighter higher than tSVF.

Application of nanofat for treatment of traumatic faecal incontinence after sphincteroplasty - A pilot study

AIM

The aim of this study was to investigate whether the application of nanofat containing stem cells improves continence in women who had previously undergone anal sphincteroplasty with unsatisfactory long-term outcomes.

METHOD

This prospective pilot study included nine women with various degrees of anal incontinence who had previously undergone anal sphincteroplasty due to obstetric trauma. In all patients, the Wexner Incontinence Score (WS) and Faecal Incontinence Quality of Life Score (FIQLS), as well as anal manometry and endoanal ultrasound measurements, were performed before the procedure and during follow-up. In all patients, liposuction was performed and 50 ml of raw lipoaspirate was obtained and processed using a NanoFat Kit device. Approximately 20 ml of the mechanically emulsified and filtrated fat was obtained and the anal sphincter complex was infiltrated with it. Patient follow-up was conducted in person or via telephone 6 and 12 months after the procedure.

RESULTS

The squeeze pressure was significantly increased 6 months after the procedure (p = 0.01). The external anal sphincter measured at the 12 o'clock position was significantly thicker (p = 0.04). A significant decrease in the WS was observed both 6 and 12 months after the procedure compared with baseline values (p < 0.05 for both).

CONCLUSION

This study is the first to show that the application of nanofat as an injectable product improves continence in patients with unsatisfactory results after sphincteroplasty, suggesting it to be a promising and effective therapeutic tool. The procedure is safe and can be easily performed as an ambulatory procedure.

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.