Efficacy and Safety of Mesenchymal Stem Cells in Treatment of Complex Perianal Fistulas: A Meta-Analysis

Systematic review and meta-analysis of the efficacy and safety of stem cell treatment of anal fistulas

BACKGROUND

Since anal fistulas can be challenging to treat; numerous innovative treatments have been proposed, including stem cell therapy. This systematic review aimed to assess pooled rates of fistula healing and adverse events associated with stem cell treatment.

METHODS

In this PRISMA-compliant systematic review we searched PubMed and Scopus for observational and randomized studies reporting outcomes of stem cell treatment for anal fistulas. The main outcome measures were successful healing and adverse effects of stem cell therapy.

RESULTS

In total, 43 studies incorporating 1160 patients (53.6% male) were included. Underlying fistula etiologies were Crohn's disease (30 studies) and cryptoglandular disease (12 studies). The main origin of stem cells was from adipose tissue (34 studies) or bone marrow (6 studies). The median follow-up duration was 12 months. The combined overall pooled healing rate was 58.1% (95% confidence interval (CI) 51.5-64.7%). The pooled healing rate for Crohn's fistulas was 60.4% (95% CI 54.7-66.2%) with adipose-derived stem cells and 63.6% (95% CI 49.4-77.7%) with bone-marrow-derived cells. The pooled healing rate for cryptoglandular fistulas was 53.8% (95% CI 35.5-72.2%) with adipose-derived stem cells. The pooled complication rate was 37.3% (95% CI 27.1-47.5%). Stem cells were associated with higher odds of anal fistula healing (odds ratio (OR): 1.81, p = 0.003) and similar odds of complications (OR: 1, p = 0.986) compared with controls.

CONCLUSIONS

Stem cell treatment of anal fistulas was associated with promising results. The healing rate in Crohn's anal fistulas was higher than in cryptoglandular fistulas. Bone-marrow-derived stem cells were associated with marginally better outcomes than were adipose-derived cells. This finding suggests that the autoimmune inflammatory etiology of Crohn's disease may respond better to autologous myoblasts than does the infectious etiology of cryptoglandular fistulas.

Understanding the anatomical basis of anorectal fistulas and their surgical management: exploring different types for enhanced precision and safety

Anorectal fistulas remain one of the most challenging conditions in colorectal surgery and require precise anatomical knowledge for successful management. This comprehensive review synthesizes the current evidence on the anatomical foundations of fistula development and treatment, particularly focusing on the cryptoglandular hypothesis and its clinical implications. A systematic analysis of the recent literature has examined the relationship between anatomical structures and fistula formation, classification systems, diagnostic modalities, and therapeutic approaches. The review revealed that anatomical considerations fundamentally influence treatment outcomes, with modern imaging techniques achieving up to 98% accuracy in delineating fistula anatomy. Key findings demonstrate that surgical success rates vary significantly based on anatomical complexity: 92-97% for simple fistulas versus 40-95% for complex cases using sphincter-sparing techniques. Emerging minimally invasive approaches and regenerative therapies, including mesenchymal stem cells, show promising results with 50-60% healing rates in complex cases. Special considerations are needed for complex cases such as Crohn's disease-related and rectovaginal fistulas. This review provides surgeons with an evidence-based framework for selecting optimal treatment strategies based on anatomical considerations, emphasizing the importance of preserving the anal sphincter function while achieving complete fistula eradication. Integrating advanced imaging, surgical techniques, and emerging therapies offers new possibilities for improving patient outcomes. This review aimed to bridge the gap between anatomical knowledge and practical surgical application, enhance clinical decision-making, and improve patient outcomes in anorectal fistula management.

Efficacy of mesenchymal stem cell-based therapies in the treatment of perianal fistulizing Crohn's disease: a systematic review and meta-analysis

BACKGROUND

Perianal lesions of Crohn's disease (CD) are complex and disabling conditions. Mesenchymal stem cell (MSC)-based therapies have emerged as an innovative approach in managing refractory perianal fistulizing CD. We conducted a systematic review and meta-analysis to describe and compare combined remission and clinical outcomes of MSC-based therapies, and then whether one approach stands out from the rest.

METHODS

We searched in MEDLINE, EMBASE and CENTRAL (up to December 31, 2023) all prospective studies assessing a local injection of MSC-based therapy in perianal fistulas of CD. The primary outcome was achievement of combined remission. MSC-based therapy strategies were compared.

RESULTS

Twenty-five studies were included in the meta-analysis, enrolling 596 patients with perianal fistulizing CD. The combined remission rate at 3, 6 and 12 months were 36.2% (95% confidence interval (CI), 24.5-49.7), 57.9% (95% CI 51.3-64.2) and 52% (95% CI 38.8-64.8), respectively. MSC-based therapies demonstrated a significant effect in achieving combined remission compared to placebo at 3 months (relative risk (RR) = 1.6; 95% CI 1.0-2.8) and at 6 months (RR = 1.5; 95% CI 1.1-1.9). At 6 months, the combined remission rate was 57.2% (95% CI 47.2-66.6) for adipose-derived stem cells (ASCs) and 55.7% (95% CI 26.4-81.5) for bone marrow-derived stem cells (BMSCs). In the network meta-analysis, allogeneic ASCs and BMSCs did not demonstrate superiority over each other (RR = 0.74; 95% CI 0.31-1.77).

CONCLUSION

MSC-based therapies are effective for achieving combined remission of refractory and/or complex perianal fistulizing CD. The optimal efficacy effect is reached after 6 months of treatment. No superiority has yet been demonstrated between ASCs and BMSCs therapies.

Autologous Microfragmented Adipose Tissue Injection in Refractory Complex Crohn's Perianal Fistulas: Long-Term Results at 6.7 Years Mean Follow-up

BACKGROUND

Nowadays, there is a clear need for new viable therapeutic options to face complex perianal Crohn's disease (PCD). Results of our previous pilot study demonstrated the efficacy and safety of local injection of autologous microfragmented adipose tissue (MFat) in this setting. This study aims to evaluate the long-term follow-up results in the same cohort of patients.

METHODS

Data on clinical and radiological remission and surgical recurrence rates were prospectively collected on the 15 patients with complex fistulizing PCD refractory to combined bio-surgical therapy, originally treated with local MFat injection, with a mean 6.7 years follow-up.

RESULTS

In our previous study, at 24-week follow-up, combined remission was reported in 66.7% of patients, while clinical remission was achieved in 93% of cases. At a 6.7-year follow-up, 9 of the 10 healed patients maintained remission. The patient with recurrence was successfully reoperated. Three out of 5 patients who failed primary combined remission were retreated, with 2 obtaining combined remission and 1 failing. One patient refused any subsequent treatment due to good quality of life. The last patient presented delayed healing at a 1-year follow-up. Overall success rate after rescue therapy at the final follow-up reached 86.6%. Safety was maintained throughout all follow-up periods.

CONCLUSIONS

This is the longest follow-up published trial on MFat injection for PCD. Our results show that patients who achieved closure in the first 24 weeks sustained response at long-term evaluation. In addition, there may be a rationale in repeating treatment as rescue therapy in not responding to patients.

Safety and efficacy of stem cell therapy for Crohn's disease: an umbrella review of systematic reviews

BACKGROUND

Crohn's disease is a chronic, relapsing form of inflammatory bowel disease marked by severe gastrointestinal inflammation and a broad range of debilitating symptoms. Despite advances in medical treatments, achieving sustained remission remains challenging for many patients. This umbrella review aims to consolidate evidence from various systematic reviews to evaluate the efficacy and safety of stem cell therapies in treating Crohn's disease.

METHODS

This review followed the Joanna Briggs Institute methodology and adhered to PRISMA guidelines. A literature search of PubMed, Web of Science, Embase, and the Cochrane Library covered records up to 20 April 2024. Only systematic reviews and meta-analyses on stem cell therapy for Crohn's disease were considered. Data were extracted and analyzed for clinical efficacy indicators like remission induction and safety metrics, including adverse events and mortality rates.

RESULTS

Sixteen systematic reviews were included, spanning studies conducted between 2009 and 2023. Stem cell therapy showed a pooled risk ratio (RR) of 1.299 (95% CI: 1.192-1.420) for clinical remission, indicating a 29.9% increased likelihood of remission compared to controls. The pooled RR for healing perianal Crohn's disease was 1.358 (95% CI: 1.13-1.631), suggesting a 35.8% increased likelihood of healing. A pooled RR of 1.481 (95% CI: 1.036-2.116) shows a 48.1% higher immediate fistula closure rate with stem cell therapy. For long-term outcomes, a RR of 1.422 (95% CI: 1.091-1.854) indicates a 42.2% increased likelihood of maintaining closure. However, stem cell therapy did not significantly impact Crohn's Disease Activity Index (CDAI) (RR: 1.154, 95% CI: 0.193-6.883) and Perianal Disease Activity Index (PDAI) scores (mean difference at 12 weeks: -0.505, 95% CI: -2.481 to 1.471; mean difference at 24 weeks: -0.338, 95% CI: -1.638 to 0.963). The safety profile was comparable to conventional therapies, with a pooled RR of 0.972 (95% CI: 0.739-1.278) for adverse events and 1.136 (95% CI: 0.821-1.572) for serious adverse events.

CONCLUSION

Stem cell therapy offers significant progress in treating Crohn's disease, particularly in complex cases, by improving fistula closure rates and suggesting potential as a supplementary therapy. Its safety profile aligns with conventional treatments, yet ongoing clinical trials are crucial to optimize its use. Continual research will enable healthcare providers to tailor more effective treatment strategies for this challenging condition.

Efficacy and safety of stem cell therapy for fistula management: an overview of existing systematic reviews

BACKGROUND

Fistulas, abnormal connections between two anatomical structures, significantly impact the quality of life and can result from a variety of causes, including congenital defects, inflammatory conditions, and surgical complications. Stem cell therapy has emerged as a promising alternative due to its potential for regenerative and immunomodulatory effects. This overview of systematic reviews aimed to assess the safety and efficacy of stem cell therapy in managing fistulas, drawing on the evidence available.

METHODS

This umbrella review was conducted following the Joanna Briggs Institute (JBI) methodology to assess the efficacy and safety of stem cell therapy for treating various types of fistulas. A comprehensive search was performed across multiple electronic databases including PubMed, Embase, Cochrane Register, and Web of Science up to 5 May 2024. Systematic reviews focusing on stem cell therapy for fistulas were included, with data extracted on study design, stem cell types, administration methods, and outcomes. The quality of the reviews was assessed using the AMSTAR 2 tool, and meta-analyses were conducted using R software version 4.3.

RESULTS

Nineteen systematic reviews were included in our umbrella review. The stem cell therapy demonstrated by significant improvements in clinical remission rates, with a relative risk (RR) of 1.299 (95% CI: 1.192-1.420). Stem cell therapy enhanced fistula closure rates, both short-term (RR=1.481; 95% CI: 1.036-2.116) and long-term (RR=1.422; 95% CI: 1.091-1.854). The safety analysis revealed no significant increase in the risk of adverse events with stem cell therapy, showing a pooled RR of 0.972 (95% CI: 0.739-1.278) for general adverse events and 1.136 (95% CI: 0.821-1.572) for serious adverse events, both of which indicate a safety profile comparable to control treatments. Re-epithelialization rates also improved (RR=1.44; 95% CI: 1.322-1.572).

CONCLUSION

Stem cell therapy shows promise as an effective and safe treatment for fistulas, particularly in inducing remission and promoting closure of complex fistulas. The findings advocate for further high-quality research to confirm these benefits and potentially incorporate stem cell therapy into standard clinical practice for fistula management. Future studies should focus on long-term outcomes and refining stem cell treatment protocols to optimize therapeutic efficacy.

ECCO Guidelines on Therapeutics in Crohn's Disease: Surgical Treatment

This article is the second in a series of two publications on the European Crohn's and Colitis Organisation [ECCO] evidence-based consensus on the management of Crohn's disease. The first article covers medical management; the present article addresses surgical management, including preoperative aspects and drug management before surgery. It also provides technical advice for a variety of common clinical situations. Both articles together represent the evidence-based recommendations of the ECCO for Crohn's disease and an update of prior ECCO Guidelines.

Comments on: "Perianal Crohn's disease: clinical implications, prognosis and use of resources"

The study by Martínez Sánchez ER et al 1 has piqued our interest as it aimed to investigate the prevalence of perianal disease, the associated phenotypical factors, its influence over prognosis and its impact in the use of health resources for patients with Crohn's disease (CD). The authors identified that perianal disease (PD) among patients with CD is very prevalent, especially if there is rectal involvement, and entails higher healthcare costs than patients without PD due to the worse evolution at the perianal and luminal level, especially in complex forms. All of this forces us to optimize treatment strategies in these types of patients. We appreciate the authors' hard work. And, we have a few comments on the article.

A Prospective, Single-Arm Study to Evaluate the Safety and Efficacy of an Autologous Blood Clot Product in the Treatment of Anal Fistula

BACKGROUND

Surgical treatment of complex perianal fistula is technically challenging, associated with risk of failure, and may require multiple procedures. In recent years, several biologic agents have been developed for permanently eradicating anal fistulous disease with variable success. In this study, the treatment is an autologous whole-blood product created from the patients' blood. It forms a provisional matrix that was found to be safe and effective in healing acute and chronic cutaneous wounds.

OBJECTIVE

The study aimed to assess the efficacy and safety of an autologous blood clot product as a treatment for transsphincteric perianal fistulas.

DESIGN

A prospective single-arm study.

SETTINGS

A single tertiary medical center.

PATIENTS

Patients with simple or complex transsphincteric fistulas confirmed by MRI were included in the study. Cause was either cryptoglandular or Crohn's disease related (in the absence of active luminal bowel disease).

INTERVENTION

The outpatient procedure was performed under general anesthesia and consisted of: 1) physical debridement and cleansing of the fistula tract; 2) suture closure of the internal opening; and 3) instillation of the autologous blood clot product into the entire tract.

MAIN OUTCOME MEASURES

Safety and efficacy at 6- and 12-months after surgery.

RESULTS

Fifty-three patients (77% men) with a median age of 42 (20-72) years were included in the study. Three patients withdrew consent, and 1 patient was lost to follow-up. At the time of this interim analysis, 49 and 33 patients completed the 6- and 12-month follow-up period. Thirty-four of the 49 patients achieved complete healing (69%) at 6 months, but 20 of the 33 patients (60%) achieved healing after 1 year. All patients who achieved healing at 6 months remained healed at the 1-year mark. In a subgroup analysis of patients with Crohn's disease, 7 of 9 patients completed 1-year follow-up, with 5 patients (71%) achieving clinical remission. No major side effects or postoperative complications were noted, but 2 adverse events occurred (admission for pain control and coronavirus 2019 infection).

LIMITATIONS

Noncomparative single-arm pilot study.

CONCLUSIONS

Treatment with an autologous blood clot product in perianal fistular disease was found to be feasible and safe, with an acceptable healing rate in both cryptoglandular and Crohn's disease fistula-in-ano. Further comparative assessment is required to determine its potential role in the treatment paradigm of fistula-in-ano. See Video Abstract .

BRAZO PARA EVALUAR LA SEGURIDAD Y EFICACIA DE RDVER, UN COGULO DE SANGRE AUTLOGO, EN EL TRATAMIENTO DE LA FSTULA ANAL

ANTECEDENTES:El tratamiento quirúrgico de la fístula perianal compleja es técnicamente desafiante, se asocia con riesgo de fracaso y puede requerir múltiples procedimientos. En los últimos años, se han desarrollado varios agentes biológicos con el fin de erradicar permanentemente la enfermedad fistulosa anal con éxito variable. El tratamiento RD2-Ver.02 es un producto de sangre total autólogo creado a partir de la sangre de los pacientes, que forma una matriz provisional que resultó segura y eficaz para curar heridas cutáneas agudas y crónicas.OBJETIVO:Evaluar la eficacia y seguridad de RD2-Ver.02 como tratamiento para las fístulas perianales transesfinterianas.DISEÑO:Un estudio prospectivo de un solo brazo.LUGARES:Un único centro médico terciario.PACIENTES:Se incluyeron en el estudio pacientes con fístulas transesfinterianas simples o complejas confirmadas mediante resonancia magnética. La etiología fue criptoglandular o relacionada con la enfermedad de Crohn (en ausencia de enfermedad intestinal luminal activa).INTERVENCIÓN:El procedimiento ambulatorio se realizó bajo anestesia general y consistió en: 1) desbridamiento físico y limpieza del trayecto fistuloso; 2) cierre con sutura de la abertura interna; y 3) instilación de RD2-Ver.02 en todo el tracto.PRINCIPALES MEDIDAS DE VALORACIÓN:Seguridad y eficacia a los 6 y 12 meses después de la cirugía.RESULTADOS:Se incluyeron en el estudio 53 pacientes (77% varones) con una mediana de edad de 42 (20-72) años. Tres pacientes retiraron su consentimiento y un paciente se perdió durante el seguimiento. En el momento de este análisis intermedio, 49 y 33 pacientes completaron el período de seguimiento de 6 y 12 meses, respectivamente. Treinta y cuatro (34) pacientes lograron una curación completa (69%) a los 6 meses, mientras que 20 de 33 pacientes (60%) lograron una curación después de un año. Todos los pacientes que lograron la curación a los 6 meses permanecieron curados al año. En un análisis de subgrupos de pacientes con enfermedad de Crohn, 7/9 pacientes completaron un seguimiento de un año y 5 pacientes (71%) alcanzaron la remisión clínica. No se observaron efectos secundarios importantes ni complicaciones postoperatorias, mientras que ocurrieron 2 eventos adversos (ingreso para control del dolor e infección por COVID-19).LIMITACIONES:Estudio piloto no comparativo de un solo brazo.CONCLUSIONES:Se encontró que el tratamiento con RD2-Ver.02 en la enfermedad fístula perianal es factible y seguro, con una tasa de curación aceptable tanto en la fístula criptoglandular como en la de Crohn en el ano. Se requiere una evaluación comparativa adicional para determinar su papel potencial en el paradigma de tratamiento de la fístula anal. (Pre-proofed version ).

Endoscopic Administration of Combined Autologous Mesenchymal Stem Cells and Platelet-Rich Plasma for the Treatment of Gastric Staple Line Leaks After Sleeve Gastrectomy

BACKGROUND

Gastric staple line leak treatment after laparoscopic sleeve gastrectomy (LSG) remains challenging. Regenerative medicine is gaining place in the accelerated treatment of damaged tissues. This study presents the first series of gastric leak treatment after LSG using endoscopic intragastric administration of combined autologous mesenchymal stem cells (MSC) and platelet-rich plasma (PRP).

METHODS

MSC-PRP harvesting and endoscopic administration techniques are described in detail. Data were prospectively gathered and analyzed. Primary endpoints were morbidity/mortality rates and fistula closure time.

RESULTS

Twelve patients (9 women, 3 men) were included. Median age was 41.5 years, median weight 105.5 kg and median BMI 38.9 kg/m2. Median time to gastric staple line leak detection was 10 days post-LSG. Median time between re-laparoscopy and MSC-PRP administration was 5 days. MSC-PRP endoscopic administration was successfully performed and tolerated by all patients, with median procedure duration of 27 min and minimal blood loss. Four postoperative complications were noted: two patients with increased tibial pain at tibial puncture site, one with tibial hematoma, and one with epigastric pain/dysphagia. Median length of hospital stay was 1 day. Gastric leak healing occurred after a median of 14 days, only two patients requiring a second MSC-PRP endoscopic injection. Median follow-up was 19 months, all patients being in good health at last contact.

CONCLUSION

Endoscopic administration of combined autologous MSC-PRP seems to be a good option for treatment of gastric leaks after sleeve gastrectomy. It is a challenging procedure that should be performed in specialized bariatric centers by expert bariatric surgeons and endoscopists after meticulous patient selection.

Local fistula injection of allogeneic human amnion epithelial cells is safe and well tolerated in patients with refractory complex perianal Crohn's disease: a phase I open label study with long-term follow up

BACKGROUND

Local fistula injection of mesenchymal stromal/stem cells (MSC) is effective for complex perianal Crohn's fistulas but is also expensive and requires specialised facilities for cell revival before administration. Human amnion epithelial cells (hAEC) are non-MSC cells with therapeutic properties. The primary aim of this study was safety of hAEC therapy. Secondary aims included hAEC efficacy, feasibility of the protocol and impact on quality of life.

METHODS

A phase I open label study of ten adults with active complex Crohn's perianal fistulas refractory to conventional treatment, including anti-tumour necrosis factor alpha therapy, was undertaken. A single dose of hAEC was injected into the fistula tract(s) after surgical closure of the internal opening(s). Study outcomes were assessed at week 24 with follow up for at least 52 weeks.

FINDINGS

Local injection of hAEC was safe, well tolerated and the injection procedure was feasible. Complete response occurred in 4 patients, and a partial response in an additional 4 patients. There was a mean reduction in the Perianal Disease Activity Index of 6.5 points (95% CI -9.0 to -4.0, p = 0.0002, paired t-test), modified Van Assche MRI Index of 2.3 points (95% CI -3.9 to -0.6, p = 0.012, paired t-test) and a mean improvement of 15.8 points (95% CI 4.9 to 26.8, p = 0.010, paired t-test) in quality of life using the Short IBD-Questionnaire in complete responders.

INTERPRETATION

Local injection of hAEC therapy for refractory complex perianal fistulising Crohn's disease appears safe, well-tolerated, feasible and demonstrated improvement. Quality of life is improved in those who achieve complete fistula healing.

FUNDING

This study was funded by competitive research grant funding from the Gastroenterological Society of Australia Seed Grant 2018.

Therapeutic Potential of Human Intestinal Organoids in Tissue Repair Approaches in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) are chronic immune-mediated conditions characterized by significant gut tissue damage due to uncontrolled inflammation. Anti-inflammatory treatments have improved, but there are no current prorepair approaches. Organoids have developed into a powerful experimental platform to study mechanisms of human diseases. Here, we specifically focus on its role as a direct tissue repair modality in IBD. We discuss the scientific rationale for this, recent parallel advances in scientific technologies (CRISPR [clustered regularly interspaced short palindromic repeats]/Cas9 and metabolic programming), and in addition, the clinical IBD context in which this therapeutic approach is tractable. Finally, we review the translational roadmap for the application of organoids and the need for this as a novel direction in IBD.

Up-to-date meta-analysis of long-term evaluations of mesenchymal stem cell therapy for complex perianal fistula

BACKGROUND

Local mesenchymal stem cell (MSC) therapy for complex perianal fistulas (PFs) has shown considerable promise. But, the long-term safety and efficacy of MSC therapy in complex PFs remain unknown.

AIM

To explore the long-term effectiveness and safety of local MSC therapy for complex PFs.

METHODS

Sources included the PubMed, EMBASE, and Cochrane Library databases. A standard meta-analysis was performed using RevMan 5.3.

RESULTS

After screening, 6 studies met the inclusion criteria. MSC therapy was associated with an improved long-term healing rate (HR) compared with the control condition [odds ratio (OR) = 2.13; 95% confidence interval (95%CI): 1.34 to 3.38; P = 0.001]. Compared with fibrin glue (FG) therapy alone, MSC plus FG therapy was associated with an improved long-term HR (OR = 2.30; 95%CI: 1.21 to 4.36; P = 0.01). When magnetic resonance imaging was used to evaluate fistula healing, MSC therapy was found to achieve a higher long-term HR than the control treatment (OR = 2.79; 95%CI: 1.37 to 5.67; P = 0.005). There were no significant differences in long-term safety (OR = 0.77; 95%CI: 0.27 to 2.24; P = 0.64).

CONCLUSION

Our study indicated that local MSC therapy promotes long-term and sustained healing of complex PFs and that this method is safe.

Senescence induces fundamental changes in the secretome of mesenchymal stromal cells (MSCs): implications for the therapeutic use of MSCs and their derivates

Mesenchymal stromal cells (MSCs) are a heterogeneous population containing multipotent adult stem cells with a multi-lineage differentiation capacity, which differentiated into mesodermal derivatives. MSCs are employed for therapeutic purposes and several investigations have demonstrated that the positive effects of MSC transplants are due to the capacity of MSCs to modulate tissue homeostasis and repair via the activity of their secretome. Indeed, the MSC-derived secretomes are now an alternative strategy to cell transplantation due to their anti-inflammatory, anti-apoptotic, and regenerative effects. The cellular senescence is a dynamic process that leads to permanent cell cycle arrest, loss of healthy cells' physiological functions and acquiring new activities, which are mainly accrued through the release of many factors, indicated as senescence-associated secretory phenotype (SASP). The senescence occurring in stem cells, such as those present in MSCs, may have detrimental effects on health since it can undermine tissue homeostasis and repair. The analysis of MSC secretome is important either for the MSC transplants and for the therapeutic use of secretome. Indeed, the secretome of MSCs, which is the main mechanism of their therapeutic activity, loses its beneficial functions and acquire negative pro-inflammatory and pro-aging activities when MSCs become senescent. When MSCs or their derivatives are planned to be used for therapeutic purposes, great attention must be paid to these changes. In this review, we analyzed changes occurring in MSC secretome following the switch from healthy to senescence status.

Mesenchymal stem cells transplantation for perianal fistulas: a systematic review and meta-analysis of clinical trials

BACKGROUND

Perianal fistulas, characterised as granulomatous inflammation of fistulas around the anal canal, are associated with significant morbidity resulting in a negative impact on quality of life and a tremendous burden to the healthcare system. Treatment of anal fistulas usually consists of anal surgery; however, results of closure rates are not satisfactory especially with complex perianal fistulas, after which many patients may suffer from anal incontinence. Recently, the administration of mesenchymal stem cells (MSCs) has shown promising efficacy. Herein, we aim to explore whether MSCs are effective for complex perianal fistulas and if they have either short-term, medium-term, long-term or over-long-term efficacy. Additionally, we want to elucidate whether factors such as drug dosage, MSC source, cell type, and disease aetiology influence treatment efficacy. We searched four online databases and analysed data based on information within the clinical trials registry. The outcomes of eligible trials were analysed with Review Manager 5.4.1. Relative risk and related 95% confidence interval were calculated to compare the effect between the MSCs and control groups. In addition, the Cochrane risk of bias tool was applied to evaluate the bias risk of eligible studies. Meta-analyses showed that therapy with MSCs was superior to conventional treatment for complex perianal fistulas in short-, long- and over-long-term follow-up phases. However, there was no statistical difference in treatment efficacy in the medium term between the two methods. Subgroup meta-analyses showed factors including cell type, cell source and cell dosage were superior compared to the control, but there was no significant difference between different experimental groups of those factors. Besides, local MSCs therapy has shown more promising results for fistulas as a result of Crohn's Disease (CD). Although we tend to maintain that MSCs therapy is effective for cryptoglandular fistulas equally, more studies are needed to confirm this conclusion in the future.

SHORT CONCLUSION

MSCs Transplantation could be a new therapeutic method for complex perianal fistulas of both cryptoglandular and CD origin showing high efficacy in the short-term to over-long-term phases, as well as high efficacy in sustained healing. The difference in cell types, cell sources and cell dosages did not influence MSCs' efficacy.

Darvadstrocel for Complex Perianal Fistulas in Japanese Adults with Crohn's Disease: A Phase 3 Study

BACKGROUND AND AIMS

Previous studies conducted in Europe suggested that darvadstrocel, a suspension of expanded, allogeneic, adipose-derived, mesenchymal stem cells, is safe and effective for treatment-refractory complex perianal fistulas in patients with Crohn's disease. The aim of this study was to evaluate the efficacy and safety of darvadstrocel for the treatment of complex perianal fistulas in Japanese adults with Crohn's disease.

METHODS

This is a phase 3, open-label, single-arm study conducted at nine sites in Japan. Adult patients with non-active or mildly active Crohn's disease and complex perianal fistulas received a single 24-mL intralesional injection of darvadstrocel [120 × 106 cells]. The primary endpoint was combined remission (clinically confirmed closure of all treated external openings that were draining at screening, and absence of collections >2 cm, [confirmed by magnetic resonance imaging] among treated fistulas) at Week 24.

RESULTS

Between March 6, 2019 and February 1, 2021, 22 patients received darvadstrocel and completed the 52-week follow-up. The proportion of patients achieving combined remission at Week 24 was 59.1% (95% confidence interval [CI], 38.5-79.6). The effect was maintained at Week 52, with 68.2% [95% CI, 48.7-87.6] of patients achieving combined remission. Treatment-related adverse events included: one [4.5%] patient with worsening of Crohn's disease and diarrhoea, and one [4.5%] patient with blood bilirubin increase. No new safety findings were identified in this study.

CONCLUSIONS

The efficacy and tolerability of darvadstrocel in Japanese adult patients with treatment-refractory complex perianal fistulas in Crohn's disease were similar to those observed in the previous European study. ClinicalTrials.gov number, NCT03706456.

Platelet-Rich stroma from Crohn's disease patients for treatment of perianal fistula shows a higher myeloid cell profile compared to non-IBD controls

BACKGROUND

New cell-based therapies are under investigation to improve perianal fistulizing Crohn's disease (pCD) healing. Autologous stromal vascular fraction combined with platelet-rich plasma (referred to as platelet-rich stroma [PRS]) is a new adipose-derived stromal therapy. The effect of Crohn's disease (CD) on adipose tissue, and adipose-derived therapies, is largely unknown. We characterized the cellular composition of subcutaneous lipoaspirate and PRS of pCD patients and non-Inflammatory Bowel Disease (IBD) controls.

METHODS

Consecutive pCD patients (≥18 years) and non-IBD controls, who underwent liposuction for the purpose of autologous PRS therapy, were included (October 2020 and March 2021). Mechanically fractionated lipoaspirate and the combined PRS product were analyzed for cell surface marker expression using fluorescence-activated cell sorting analysis.

RESULTS

Twenty-three patients (37.8 [IQR 30.7-45.0] years; 9 [39.1 %] male; 11CD patients) were included. Similar total number of cells were found in CD and non-IBD lipoaspirate (CD 8.23 ± 1.62*10⁵ cells/mL versus non-IBD 12.20 ± 3.39*10⁵). Presence of stromal cells, endothelial like cells, immune cells, T-cells, myeloid cells and M2/M1 macrophage ratio were similar in CD and non-IBD lipoaspirate. In PRS samples, more cells/mL were seen in CD patients (P = 0.030). Myeloid cells were more abundant in CD PRS samples (P = 0.007), and appeared to have a higher regulatory M2/M1 ratio. Interdonor variation was observed between lipoaspirate and PRS samples.

CONCLUSIONS

The composition of CD and non-IBD lipoaspirate were found to be similar and interdonor variation was observed. However, PRS from CD patients showed more myeloid cells with a regulatory phenotype. Crohn's disease does not appear to alter the immunological composition of adipose-derived products.

Mesenchymal (Stem) Stromal Cells Based as New Therapeutic Alternative in Inflammatory Bowel Disease: Basic Mechanisms, Experimental and Clinical Evidence, and Challenges

Inflammatory bowel diseases (IBD) are an example of chronic diseases affecting 40% of the population, which involved tissue damage and an inflammatory process not satisfactorily controlled with current therapies. Data suggest that mesenchymal stem cells (MSC) may be a therapeutic option for these processes, and especially for IBD, due to their multifactorial approaches such as anti-inflammatory, anti-oxidative stress, anti-apoptotic, anti-fibrotic, regenerative, angiogenic, anti-tumor, or anti-microbial. However, MSC therapy is associated with important limitations as safety issues, handling difficulties for therapeutic purposes, and high economic cost. MSC-derived secretome products (conditioned medium or extracellular vesicles) are therefore a therapeutic option in IBD as they exhibit similar effects to their parent cells and avoid the issues of cell therapy. In this review, we proposed further studies to choose the ideal tissue source of MSC to treat IBD, the implementation of new standardized production strategies, quality controls and the integration of other technologies, such as hydrogels, which may improve the therapeutic effects of derived-MSC secretome products in IBD.

Comparison between recent sphincter-sparing procedures for complex anal fistulas-ligation of intersphincteric tract vs transanal opening of intersphincteric space

Complex anal fistulas are difficult to treat. The main reasons for this are a higher recurrence rate and the risk of disrupting the continence mechanism because of sphincter involvement. Due to this, several sphincter-sparing procedures have been developed in the last two decades. Though moderately successful in simple fistulas (50%-75% healing rate), the healing rates in complex fistulas for most of these procedures has been dismal. Only two procedures, ligation of intersphincteric fistula tract and transanal opening of intersphincteric space have been shown to have good success rates in complex fistulas (60%-95%). Both of these procedures preserve continence while achieving high success rates. In this opinion review, I shall outline the history, compare the pros and cons, indications and contraindications and future application of both these procedures for the management of complex anal fistulas.

Intraperitoneally Delivered Mesenchymal Stem Cells Alleviate Experimental Colitis Through THBS1-Mediated Induction of IL-10-Competent Regulatory B Cells

Mesenchymal stem cells (MSCs) show promising therapeutic potential in treating inflammatory bowel disease (IBD), and intraperitoneal delivery of MSCs have become a more effective route for IBD treatment. However, the underlying mechanisms are still poorly understood. Here, we found that intraperitoneally delivered MSCs significantly alleviated experimental colitis. Depletion of peritoneal B cells, but not macrophages, clearly impaired the therapeutic effects of MSCs. Intraperitoneally delivered MSCs improved IBD likely by boosting the IL-10-producing B cells in the peritoneal cavity, and a single intraperitoneal injection of MSCs could significantly prevent disease severity in a recurrent mouse colitis model, with lower proinflammation cytokines and high level of IL-10. The gene expression profile revealed that thrombospondin-1 (THBS1) was dramatically upregulated in MSCs after coculture with peritoneal lavage fluid from colitis mice. Knockout of THBS1 expression in MSCs abolished their therapeutic effects in colitis and the induction of IL-10-producing B cells. Mechanistically, THBS1 modulates the activation of transforming growth factor-β (TGF-β), which combines with TGF-β receptors on B cells and contributes to IL-10 production. Blocking the interaction between THBS1 and latent TGF-β or inhibiting TGF-β receptors (TGF-βR) significantly reversed the THBS1-mediated induction of IL-10-producing B cells and the therapeutic effects on colitis. Collectively, our study revealed that intraperitoneally delivered MSCs secreted THBS1 to boost IL-10⁺Bregs and control the progression and recurrence of colitis, providing new insight for the prevention and treatment of IBD.

Mesenchymal Stem Cells for Cryptoglandular Anal Fistula: Current State of Art

Anal fistula is a common disease that needs surgical treatment to be resolved. Despite a variety of surgical options, the major problem is still to cure complex fistulas without any recurrence in the long-term follow-up but, at the same time, to avoid an impairment of continence. In recent years, one solution has been the application of mesenchymal stem cells derived from adipose tissue, especially in association with other treatments, such as the use of fibrin glue or the previous application of a seton. Their initial use in fistulas associated with Crohn's disease has shown encouraging results. In this non-systematic review our aim is to analyze the use in cryptoglandular fistulas: the rate of healing is not so high, and the number of studies is limited. Therefore, further randomized controlled trials are needed to establish their efficacy in the case of complex cryptoglandular anal fistulas and their possible complications.

Mesenchymal Stromal Cell Therapy Improves Refractory Perianal Fistula in Crohn's Disease: Case Series Clinical Interventional Study

OBJECTIVE

Perianal fistulas in Crohn's disease (CD) are the main challenges in inflammatory bowel diseases (IBDs). Some of the fistulas are refractory to any therapeutic strategy. The aim of this study was to evaluate the therapeutic effects of mesenchymal stromal cells (MSCs) as a novel promising modality for the treatment of fistulizing CD.

MATERIALS AND METHODS

This case series clinical interventional study was conducted from 2014 to 2017 at Shariati Hospital, an IBD referral center in Tehran, Iran. Refractory adult patients with CD who had draining perianal fistulas were enrolled in this study. All patients were examined by a colorectal surgeon and the fistula imaging studies were performed by pelvic magnetic resonance imaging (MRI). After autologous bone marrow (BM) aspiration and MSCs isolation, the cells were cultured and passaged under current good manufacturing practice (cGMP) conditions. Four intra-fistula injections of cells, each containing 40×106 MSCs suspended in fibrin glue, were administered by an expert surgeon every 4 weeks. Procedure safety, feasibility and closure of the perianal fistulas at week 24 were assessed. Clinical examination and MRI findings were considered as the primary end points.

RESULTS

In total, 5 patients (2 males and 3 females) were enrolled in this study. No adverse events were observed during the six-month follow-up in these patients. Both the Crohn's Disease Activity Index (CDAI) and Perianal Disease Activity Index (PDAI) scores decreased in all patients after cell injections and one patient achieved complete remission with closure of fistulas, discontinuation of fistula discharge, and closure of the external opening.

CONCLUSION

Local injection of MSCs combined with fibrin glue is potentially a safe and effective therapeutic approach for complex perianal fistulas in patients with CD.

Stem cell therapy applied for digestive anastomosis: Current state and future perspectives

BACKGROUND

Digestive tract resections are usually followed by an anastomosis. Anastomotic leakage, normally due to failed healing, is the most feared complication in digestive surgery because it is associated with high morbidity and mortality. Despite technical and technological advances and focused research, its rates have remained almost unchanged the last decades. In the last two decades, stem cells (SCs) have been shown to enhance healing in animal and human studies; hence, SCs have emerged since 2008 as an alternative to improve anastomoses outcomes.

AIM

To summarise the published knowledge of SC utilisation as a preventative tool for hollow digestive viscera anastomotic or suture leaks.

METHODS

PubMed, Science Direct, Scopus and Cochrane searches were performed using the key words "anastomosis", "colorectal/colonic anastomoses", "anastomotic leak", "stem cells", "progenitor cells", "cellular therapy" and "cell therapy" in order to identify relevant articles published in English and Spanish during the years of 2000 to 2021. Studies employing SCs, performing digestive anastomoses in hollow viscera or digestive perforation sutures and monitoring healing were finally included. Reference lists from the selected articles were reviewed to identify additional pertinent articles.Given the great variability in the study designs, anastomotic models, interventions (SCs, doses and vehicles) and outcome measures, performing a reliable meta-analysis was considered impossible, so we present the studies, their results and limitations.

RESULTS

Eighteen preclinical studies and three review papers were identified; no clinical studies have been published and there are no registered clinical trials. Experimental studies, mainly in rat and porcine models and occasionally in very adverse conditions such as ischaemia or colitis, have been demonstrated SCs as safe and have shown some encouraging morphological, functional and even clinical results. Mesenchymal SCs are mostly employed, and delivery routes are mainly local injections and cell sheets followed by biosutures (sutures coated by SCs) or purely topical. As potential weaknesses, animal models need to be improved to make them more comparable and equivalent to clinical practice, and the SC isolation processes need to be standardised. There is notable heterogeneity in the studies, making them difficult to compare. Further investigations are needed to establish the indications, the administration system, potential adjuvants, the final efficacy and to confirm safety and exclude definitively oncological concerns.

CONCLUSION

The future role of SC therapy to induce healing processes in digestive anastomoses/sutures still needs to be determined and seems to be currently far from clinical use.

Adipose-Derived Stem Cells in the Treatment of Perianal Fistulas in Crohn's Disease: Rationale, Clinical Results and Perspectives

Between 20 to 25% of Crohn’s disease (CD) patients suffer from perianal fistulas, a marker of disease severity. Seton drainage combined with anti-TNFα can result in closure of the fistula in 70 to 75% of patients. For the remaining 25% of patients there is room for in situ injection of autologous or allogenic mesenchymal stem cells such as adipose-derived stem/stromal cells (ADSCs). ADSCs exert their effects on tissues and effector cells through paracrine phenomena, including the secretome and extracellular vesicles. They display anti-inflammatory, anti-apoptotic, pro-angiogenic, proliferative, and immunomodulatory properties, and a homing within the damaged tissue. They also have immuno-evasive properties allowing a clinical allogeneic approach. Numerous clinical trials have been conducted that demonstrate a complete cure rate of anoperineal fistulas in CD ranging from 46 to 90% of cases after in situ injection of autologous or allogenic ADSCs. A pivotal phase III-controlled trial using allogenic ADSCs (Alofisel^®) demonstrated that prolonged clinical and radiological remission can be obtained in nearly 60% of cases with a good safety profile. Future studies should be conducted for a better knowledge of the local effect of ADSCs as well as for a standardization in terms of the number of injections and associated procedures.