Efficacy of stem cells therapy for Crohn's fistula: a meta-analysis and systematic review

Mesenchymal stem cell therapy for therapy refractory complex Crohn's perianal fistulas: a case series

BACKGROUND

Mesenchymal stem cell treatment (MST) has emerged as a new therapeutic strategy for Crohn's perianal fistulas. It has been demonstrated that a fibrotic tract on MRI with a MAGNIFI-CD score ≤ 6 is the best predictor for long-term clinical closure. Therefore, the aim of the current study was to analyse the effectiveness of MST for complex Crohn's perianal fistulas based on MRI.

METHODS

Consecutive patients with complex Crohn's perianal fistulas, previously failing both anti-TNF treatment and surgical closure, who had surgical closure of the internal opening with MST were included. The primary endpoint was radiological remission of the fistula(s) defined as a MAGNIFI-CD ≤ 6 on MRI, read by an experienced radiologist.

RESULTS

Between December 2019 and March 2023, 30 patients (15 males) with 48 fistula tracts were included with a median follow-up of 16.5 months. Radiological remission was achieved in thirteen patients (43.3%) after a median follow-up of 5.0 months (IQR 3.0-6.0). The median MAGNIFI-CD at baseline was 15.0 (IQR 7.0-20.0) which significantly decreased to 8.0 (IQR 3.0-15.0) after treatment (p = 0.001). Clinical closure was achieved in 21 patients (70.0%). Three patients (14.3%) developed a recurrence during long-term FU, all with clinically closed fistula(s), but no radiological remission. The median PDAI decreased significantly from 10.5 (IQR 7.0-14.0) to 4.0 (IQR 0.0-7.3) (p = 0.001).

CONCLUSION

MST is a promising treatment strategy for therapy refractory Crohn's perianal fistulas, resulting in > 40% radiological remission, clinical closure in 70% and a significant improvement in quality of life. No recurrences were seen in patients with radiological remission.

Challenges in IBD Research 2024: Novel Technologies

Novel technology is one of the five focus areas of the Challenges in Inflammatory Bowel Disease (IBD) Research 2024 document. Building off the Challenges in IBD Research 2019 document, the Foundation aims to provide a comprehensive overview of current gaps in IBD research and deliver actionable approaches to address them with a focus on how these gaps can lead to advancements in interception, remission, and restoration for these diseases. The document is the result of a multidisciplinary collaboration from scientists, clinicians, patients, and funders and represents a valuable resource for patient-centric research prioritization. Specifically, the Novel Technologies section focuses on addressing key research gaps to enable interception and improve remission rates in IBD. This includes testing predictions of disease onset and progression, developing novel technologies tailored to specific phenotypes, and facilitating collaborative translation of science into diagnostics, devices, and therapeutics. Proposed priority actions outlined in the document include real-time measurement of biological changes preceding disease onset, more effective quantification of fibrosis, exploration of technologies for local treatment of fistulas, and the development of drug delivery platforms for precise, location-restricted therapies. Additionally, there is a strong emphasis on fostering collaboration between various stakeholders to accelerate progress in IBD research and treatment. Addressing these research gaps necessitates the exploration and implementation of bio-engineered novel technologies spanning a spectrum from materials to systems. By harnessing innovative ideas and technologies, there's a collective effort to enhance patient care and outcomes for individuals affected by IBD.

Optimal Management of Refractory Crohn's Disease: Current Landscape and Future Direction

Refractory Crohn's disease, defined as ongoing inflammation despite the trial of multiple advanced therapies, impacts a number of individuals with Crohn's disease, and leads to significant burden in quality of life and cost. Interventions such as early implementation of advanced therapies, optimization of current therapies prior to switching to an alternative, as well as understanding the overlapping pathophysiology between immune-mediated disorders, however, can help shift the current landscape and reduce the number of patients with refractory disease. As such, in this review we summarize the key takeaways of the latest research in the management of moderate-to-severe Crohn's disease, focusing on maximization of our currently available medications, while also exploring topics such as combination advanced therapies. We also describe evidence for emerging and alternative therapeutic modalities, including fecal microbiota transplant, exclusive enteral feeding, hyperbaric oxygen, stem cell therapy, bone marrow transplant, and posaconazole, with a focus on both the potential impact and specific indications for each.

A Comprehensive Exploration of Therapeutic Strategies in Inflammatory Bowel Diseases: Insights from Human and Animal Studies

Inflammatory bowel disease (IBD) is a collective term for a group of chronic inflammatory enteropathies which are characterized by intestinal inflammation and persistent or frequent gastrointestinal signs. This disease affects more than 3.5 million humans worldwide and presents some similarities between animal species, in particular, dogs and cats. Although the underlying mechanism that triggers the disease is not yet well understood, the evidence suggests a multifactorial etiology implicating genetic causes, environmental factors, microbiota imbalance, and mucosa immune defects, both in humans and in dogs and cats. Conventional immunomodulatory drug therapies, such as glucocorticoids or immunosuppressants, are related with numerous adverse effects that limit its long-term use, creating the need to develop new therapeutic strategies. Mesenchymal stromal cells (MSCs) emerge as a promising alternative that attenuates intestinal inflammation by modulating inflammatory cytokines in inflamed tissues, and also due to their pro-angiogenic, anti-apoptotic, anti-fibrotic, regenerative, anti-tumor, and anti-microbial potential. However, this therapeutic approach may have important limitations regarding the lack of studies, namely in veterinary medicine, lack of standardized protocols, and high economic cost. This review summarizes the main differences and similarities between human, canine, and feline IBD, as well as the potential treatment and future prospects of MSCs.

Efficacy and Safety of Hyperbaric Oxygen Therapy in Fistulizing Crohn's Disease: A Systematic Review and Meta-analysis

BACKGROUND

Hyperbaric oxygen therapy (HBOT) delivers 100% oxygen in a pressurized chamber, increasing tissue oxygen levels and regulating inflammatory pathways. Mounting evidence suggests that HBOT may be effective for inflammatory bowel disease. Our systematic review and meta-analysis aimed to quantify the efficacy and safety of HBOT in fistulizing Crohn's disease (CD).

METHODS

A systematic review was conducted using the EMBASE, Web of Science, Pubmed, and Cochrane Library databases according to the "Preferred Reporting Items for Systematic Reviews and Meta-analyses" criteria. Study bias was assessed using the Cochrane Handbook guidelines.

RESULTS

Sixteen studies with 164 patients were included in the analysis. For all fistula subtypes, the pooled overall clinical response was 87% (95% CI: 0.70-0.95, I2 = 0) and the pooled clinical remission was 59% (95% CI: 0.35-0.80, I2 = 0). The overall clinical response was 89%, 84%, and 29% for perianal, enterocutaneous, and rectovaginal fistulas, respectively. On meta-regression, hours in the chamber and the number of HBOT sessions were not found to correlate with clinical response. The pooled number of adverse events was low at 51.7 per 10,000 HBOT sessions for all fistula types (95% CI: 16.8-159.3, I2 = 0). The risk of bias was observed across all studies.

CONCLUSION

HBOT is a safe and potentially effective treatment option for fistulizing CD. Randomized control trials are needed to substantiate the benefit of HBOT in fistulizing CD.

The Effectiveness of Adipose Tissue-Derived Mesenchymal Stem Cells Mixed with Platelet-Rich Plasma in the Healing of Inflammatory Bowel Anastomoses: A Pre-Clinical Study in Rats

Introduction: Multiple factors have been linked with increased risk of anastomotic leak in bowel surgery, including infections, inflammatory bowel disease, patient comorbidities and poor surgical technique. The aim of this study was to investigate the positive effect, if any, of adipose derived mesenchymal stem cells (MSCs) mixed with platelet-rich plasma (PRP) in the healing of bowel anastomoses, in an inflammatory environment after establishment of experimental colitis. Materials and Methods: Thirty-five male Wistar rats were divided into five groups of seven animals: normal controls, colitis controls, PRP, MSCs, and PRP+MSCs. All groups underwent laparotomy, one-cm segmental colectomy and anastomosis in situ. In the colitis group, colectomy was performed at the affected area. Colitis was previously established by transrectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) except for the normal controls. Post-mortem histopathological, tissue hydroxyproline and anastomotic bursting pressure (ABP) assessments were performed. The Mann-Whitney U test was used to assess statistical significance differences between groups. Results: No perioperative mortality was noted. Tissue hydroxyproline and ABP were significantly increased in the group of PRP+MSCs compared to colitis controls (p = 0.0151 and p = 0.0104, respectively). Inflammatory cell infiltration was lower and fibroblast activity higher in PRP+MSCs group, but not statistically significant (p > 0.05). Neoangiogenesis (p = 0.0073) and anastomotic area epithelialization (p = 0.0182) were significantly higher in PRP + MSCs group compared to colitis controls. Discussion: The synergistic effect of the PRP and MSCs is apparently responsible for the improved healing markers in bowel anastomoses even on inflammatory bowel. This gives hope for primary anastomoses and stoma saving in many emergency and/or elective circumstances, especially in immunocompromised or malnourished patients, even in cases with inflammation or peritonitis. Clinical studies should follow in order to support the clinical application of PRP+MSCs in gastrointestinal anastomoses.

Where Are We and Where to Next?-The Future of Perianal Crohn's Disease Management

Perianal fistulizing Crohn's Disease (pCD) affects about 25% of patients with Crohn's Disease (CD). It remains a difficult entity to manage with a therapeutic ceiling of treatment success despite improving medical and surgical management. The refractory nature of the disease calls for an imminent need to better understand its immunopathogenesis and classification to better streamline our treatment options. In this article, we overview the current state of pCD management and discuss where the future of its management may lie.

Stem cells in treatment of crohn's disease: Recent advances and future directions

BACKGROUND AND AIM

Crohn's disease (CD) is an inflammatory bowel disease that can affect any part of the intestine. There is currently no recognized cure for CD because its cause is unknown. One of the modern approaches that have been suggested for the treatment of CD and other inflammatory-based disorders is cell therapy.

METHODS

Search terms were stem cell therapy, CD, adipose-derived stem cells, mesenchymal stem cells, and fistula. Of 302 related studies, we removed duplicate and irrelevant papers and identified the ones with proper information related to our scope of the research by reviewing all the abstracts and categorizing each study into the proper section.

RESULTS AND CONCLUSION

Nowadays, stem cell therapy is widely implied in treating CD. Although mesenchymal and adipose-derived tissue stem cells proved to be safe in treating Crohn's-associated fistula, there are still debates on an optimal protocol to use. Additionally, there is still a lack of evidence on the efficacy of stem cell therapy for intestinal involvement of CD. Future investigations should focus on preparing a standard protocol as well as luminal stem cell therapy in patients.

Unlocking the Potential of Mesenchymal Stem Cells in Gynecology: Where Are We Now?

Stem cells, with their remarkable capacity for differentiation into diverse cell types, are vital for the development as well as maintenance of health and homeostasis. Two unique abilities set them apart from other cells: self-renewal and the capacity for differentiation. They play important roles in embryogenesis, development, regeneration, and various other processes. Over the last decade, there has been increased interest in their potential use in the treatment of numerous diseases and disorders across multiple fields of medicine in acute, chronic, innate, and acquired diseases. Stem cells are key to maintaining the body's homeostasis and regulating growth and tissue functions. There are several types of stem cells-embryonic, adult, and human-induced pluripotent cells. Currently, mesenchymal stem cells are of great interest due to their regenerative, immunomodulatory, analgesic, and antimicrobial (anti-inflammatory) effects. Recent studies have shown the potent regenerative effect of stem cell therapy in gynecologic diseases such as infertility, Asherman syndrome, lichen sclerosus, polycystic ovary syndrome, premature ovarian insufficiency, genitourinary syndrome of menopause, and rectovaginal fistulas. Moreover, the successful isolation of oogonial stem cells could lead to a revolution in the field of gynecology and the potential treatment of the conditions discussed. This review aims to provide a better understanding of the latest therapeutic options involving stem cells and raise awareness of this promising yet not widely known topic in gynecology and medicine in general.

A nanofiber-hydrogel composite improves tissue repair in a rat model of Crohn's disease perianal fistulas

Perianal fistulas (PAFs) represent a severe complication of Crohn's disease (CD). Despite the advent of biologic and small-molecule therapeutics for luminal disease, PAFs in CD (CD-PAF) are relatively resistant to treatment, with less than 50% responding to any therapy. We report an injectable, biodegradable, mechanically fragmented nanofiber-hydrogel composite (mfNHC) loaded with adipose-derived stem cells (ADSCs) for the treatment of fistulas in a rat model of CD-PAF. The ADSC-loaded mfNHC results in a higher degree of healing when compared to surgical treatment of fistulas, which is a standard treatment. The volume of fistulas treated with mfNHC is decreased sixfold compared to the surgical treatment control. Molecular studies reveal that utilization of mfNHC reduced local inflammation and improved tissue regeneration. This study demonstrates that ADSC-loaded mfNHC is a promising therapy for CD-PAF, and warrants further studies to advance mfNHC toward clinical translation.

The Intersection of Human and Veterinary Medicine-A Possible Direction towards the Improvement of Cell Therapy Protocols in the Treatment of Perianal Fistulas

The effective treatment of perianal fistulizing Crohn's disease is still a challenge. Local administration of mesenchymal stromal cells (MSCs) is becoming a part of accepted treatment options. However, as a fledgling technique, it still can be optimized. A new trend in translational research, which is in line with "One Health" approach, bases on exploiting parallels between naturally occurring diseases affecting humans and companion animals. Canine anal furunculosis (AF) has been indicated as condition analogous to human perianal Crohn's disease (pCD). This narrative review provides the first comprehensive comparative analysis of these two diseases based on the published data. The paper also outlines the molecular mechanisms of action of MSCs which are likely to have a role in modulating the perianal fistula niche in humans, and refers them to the current knowledge on the immunomodulatory properties of canine MSCs. Generally, the pathogenesis of both diseases shares main determinants such as the presence of genetic predispositions, dysregulation of immune response and the relation to intestine microbiota. However, we also identified many aspects which should be further specified, such as determining the frequency of true fistulas formation in AF patients, elucidating the role of TNF and Th17 pathway in the pathogenesis of AF, or clarifying the role of epithelial-to-mesenchymal transition phenomenon in the formation of canine fistulae. Nevertheless, the available data support the hypothesis that the results from testing cell therapies in dogs with anal furunculosis have a significant translational value in optimizing MSC transplants procedures in pCD patients.

New and Emerging Treatments for Inflammatory Bowel Disease

BACKGROUND

The specific etiopathogenesis of inflammatory bowel disease (IBD) is still unknown. Although the conventional anti-inflammatory or immunomodulatory drugs relatively nonspecific to pathogenesis have been quite useful in many cases, elucidating the pathogenesis has gradually facilitated developments of disease-specific therapies for refractory cases in the last 2 decades.

SUMMARY

With a greater understanding of the multiple overactive signaling pathways of the gut mucosal immune response and enhanced leukocyte trafficking, several biological agents or small molecule drugs following the first novel biologic, anti-tumor necrosis factor α (anti-TNFα), have been developed against several modes of action including adhesion molecules, sphingosine-1-phospate receptors, cytokines (IL-12/23, TL1A, and IL-36), Janus kinase (JAK), and phosphodiesterase. Although preceding biological agents have dramatically changed the IBD treatment strategy, many patients still require alternative therapies due to failure or side effects. Newer treatments are now expected to be provided for better efficacy with an improved adverse event profile. In addition, translational studies have highlighted the new therapeutic concepts' potential, including modulation of host-microbiome interactions, stem therapy for perianal fistula, regulation of fibrosis, regulation of the gut-brain axis, and control of previously less targeted immune cells (B cells and innate lymphoid cells). This paper comprehensively reviewed not only the latest already or shortly available therapies but also emerging promising treatments that will be hopefully established in the future for IBD.

KEY MESSAGES

Many kinds of new treatments are available, and promising treatments with new perspectives are expected to emerge for refractory IBD in the future.

Endoscopic Treatment of Acute and Chronic Anastomotic Leaks from Inflammatory Bowel Disease Surgery

Acute or chronic anastomotic leak is a common complication after any gastrointestinal surgery in inflammatory bowel disease (IBD). The underlying disease of the bowel, comorbidities, malnutrition, anemia, and concurrent use of corticosteroids increase the risk for the development of anastomotic leaks. Anastomotic leak is traditionally managed with surgery. However, recent innovation has allowed the use of endoscopic methods in the management of some anastomotic leaks and their consequences. This article discusses a variety of endoscopic techniques that have either been established or are under current evaluation, for the management of anastomotic leaks in patients with IBD.

Efficacy of Kegel exercises in preventing incontinence after partial division of internal anal sphincter during anal fistula surgery

BACKGROUND

The transanal opening of intersphincteric space (TROPIS) procedure, performed to treat complex anal fistulas, preserves the external anal sphincter (EAS) but involves partial incision of the internal anal sphincter (IAS).

AIM

To ascertain the incidence of incontinence after the division of the IAS as is done in TROPIS and to evaluate whether regular Kegel exercises (KE) in the postoperative period can prevent incontinence due to IAS division.

METHODS

Patients operated on for high complex fistulas and having no preoperative continence problem (score = 0) were included in the study. All patients were operated on by the TROPIS procedure and were recommended KE (pelvic contraction exercises) 50 times/day. KE were commenced on the 10^th postoperative day and continued for 1 year. Incontinence was evaluated objectively (by modified Vaizey’s scores) in the immediate postoperative period (Pre-KE group) and on long-term follow-up (Post-KE group). The incontinence scores in both groups were compared to evaluate the efficacy of KE.

RESULTS

Of 102 anal fistula patients operated on between July 2018 and July 2020 were included in this study. There were 90 males, the mean age was 42.3 ± 12.8, and the median follow-up was 30 mo (18-42 mo). Three patients were lost to follow-up. There were 65 recurrent fistulas, 92 had multiple tracts, 42 had associated abscess, 46 had horseshoe fistula and 34 were supralevator fistulas. All were magnetic resonance imaging-documented high fistulas (> 1/3 EAS involved). Overall incontinence occurred in 31% patients (Pre-KE group) with urge and gas incontinence accounting for the majority of cases (28.3%). The mean incontinence scores in the Pre-KE group were 1.19 ± 1.96 (in 31 patients, solid = 0, liquid = 7, gas = 8, urge = 24) and in the Post-KE group were 0.26 ± 0.77 (in 13 patients, solid = 0, liquid = 2, gas = 3, urge = 10) (P = 0.00001, t-test).

CONCLUSION

Division of the IAS led to incontinence, mainly urge incontinence, and also to a mild degree of gas and liquid incontinence. However, regular KE led to a significant reduction in incontinence (both in the number of affected patients and the severity of scores in these patients).

The Optimal Management of Fistulizing Crohn’s Disease: Evidence beyond Randomized Clinical Trials

Fistulizing Crohn’s disease (FCD) remains the most challenging aspect of treating patients with CD. FCD can occur in up to 30% of patients with CD and may lead to significant disability and impaired quality of life. The optimal treatment strategies for FCD require a multidisciplinary approach, including a combined medical and surgical approach. The therapeutic options for FCD are limited due to sparse evidence from randomized clinical trials (RCTs). The current recommendations are mainly based on post hoc analysis from RCTs, real-world clinical studies and expert opinion. There is variation in everyday clinical practice amongst gastroenterologists and surgeons. The evidence for anti-tumor necrosis factor therapy is the strongest in the treatment of FCD. However, long-term fistula healing can be achieved in only 30–50% of patients. In recent years, emerging data in the advent of therapeutic modalities, including the use of new biologic agents, therapeutic drug monitoring, novel surgical methods and mesenchymal stem cell therapy, have been shown to improve outcomes in achieving fistula healing. This review summarizes the existing literature on current and emerging therapies to provide guidance beyond RCTs in managing FCD.

Stem cell transplantation for induction of remission in medically refractory Crohn's disease

BACKGROUND

Crohn's disease (CD) is an inflammatory bowel disease that causes inflammation and stricture, of any part of the mucosa and the gut wall. It forms skip lesions, sparing the areas in between the affected parts of the gastrointestinal tract. Crohn's disease could have one of three complications; fistula, intestinal obstruction due to stricture, or gastrointestinal inflammation presenting as severe diarrhoea. Stem cell therapy (SCT) is an innovative treatment that has been recently used in CD. The exact role of SCT in CD is still unclear. Stem cells modify the immunity of the patients or act as a "reset tool" for the immune system as in the case of systemically-injected stem cells, or regenerate the affected area of necrotic and inflammatory tissue as in the case of local injection into the lesion. Stem cells are a wide variety of cells including pluripotent stem cells or differentiated stem cells. The hazards range from rejection to symptomatic manifestations as fever or increase infection.  OBJECTIVES: The objective of this Cochrane systematic review is to assess the effects of stem cell transplantation compared to standard of care alone or with placebo on efficacy and safety outcomes in patients with refractory CD.

SEARCH METHODS

We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and clinical trial registries (Clinicaltrials.gov, World Health Organization-International Clinical Trials Registry Platform WHO ICTRP) from inception to 19 March 2021, without any language, publication year, or publication status restrictions. In addition, we searched references of included studies and review articles for further references. An update of the published studies was done during the writing of the review.

SELECTION CRITERIA

We included only randomised controlled trials (RCTs) that assessed the effectiveness and safety of SCT in refractory CD versus standard care alone (control) or with placebo.

DATA COLLECTION AND ANALYSIS

Two review authors (SEN and SFA) independently screened the studies retrieved from the search results for inclusion, extracted data and assessed the risk of bias. Any disagreement was resolved through a consensus between the authors. We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We conducted our search on 19 March 2021 and identified 639 records. We added two records by a manual search of the published reviews on the topic to a total of 641 records. The Covidence program removed 125 duplicates making a total of 516 reports. Two review authors (SEN and SFA) screened titles and abstracts and excluded 451 records with the remaining 65 for full-text records screened independently by the two authors; only 18 studies were considered for inclusion.  We included seven RCTs with a total of 442 participants for the meta-analysis. The intervention group included 234 patients, and the control group included 208 patients. Nine trials are ongoing and, two abstracts are awaiting classification. All patients in the control and intervention groups received the standard therapy for CD. Only three studies used blinding methods for the control group in the form of a placebo, with one study of the three stated that the blinding method was inefficient. The patients and personnel were aware of the intervention in the rest of the four studies as they were open-label trials. However, the effect of unblinding was balanced by the low risk of detection bias in five of the included studies. The evidence is uncertain about the effect of SCT on achieving clinical remission as compared to control/placebo (risk ratio (RR) 1.88, 95% Confidence Interval (CI) 0.80 to 4.41; 3 studies; low-certainty evidence). The evidence is very uncertain about the effect of SCT on achieving Crohn's Disease Activity Index (CDAI) <150 at 24 weeks compared to control (RR1.02 95% CI 0.67 to 1.56; 4 studies; very-low certainty evidence). SCT is likely to achieve fistula closure as compared to the control/placebo both in the short term (RR 1.48, 95% CI 1.12 to 1.96); low-certainty evidence) and in the long term (RR 1.42, 95% CI 1.09 to 1.87; 4 studies; low-certainty evidence) follow-up. The evidence is very uncertain about the effect of SCT to cause no difference in the number of total adverse events as compared to the control/placebo (RR 0.99, 95% CI [0.88 to  1.13); 4 studies; very-low-certainty evidence). However, SCT is likely to increase the number of serious adverse events as compared to the control/placebo (RR 1.22, 95% CI 0.88 to 1.67; 7 studies; low-certainty evidence). The evidence is very uncertain about the effect of SCT to decrease the withdrawal due to adverse events as compared to the control/placebo (RR 0.78, 95% CI 0.32 to 1.89; 3 studies; very-low certainty evidence). Funding by pharmaceutical companies was found in three studies, with one including more than 50% of our studied population.

AUTHORS' CONCLUSIONS

SCT shows an uncertain effect on clinical remission with low certainty of evidence. SCT shows an uncertain effect on CDAI score to reach <150 after 24 weeks of treatment, with very low certainty evidence. SCT shows beneficial effects on fistula-closure during short and long-term follow-up with low-certainty evidence in both outcomes. There was no change in the total number of adverse events with SCT as compared to control, with very low certainty evidence. While there was a moderate effect on increasing the number of serious adverse events in the SCT group, as compared to the control with low-certainty evidence. Withdrawal due to adverse events was slightly higher in the control group with very low certainty evidence. All the participants were refractory to standard medical treatment, but the number of participants was small, this may limit the generalizability of the results. Further research is needed for validation. More objective outcomes are needed in the assessment of stem cell effectiveness in the treatment of Crohn's disease, especially the intestinal CD subtype; with standardization of the dose, methods of stem cell preparation, route of administration, and inclusion criteria to the studies to achieve clear results.

Guidelines to diagnose and treat peri-levator high-5 anal fistulas: Supralevator, suprasphincteric, extrasphincteric, high outersphincteric, and high intrarectal fistulas

Supralevator, suprasphincteric, extrasphincteric, and high intrarectal fistulas (high fistulas in muscle layers of the rectal wall) are well-known high anal fistulas which are considered the most complex and extremely challenging fistulas to manage. Magnetic resonance imaging has brought more clarity to the pathophysiology of these fistulas. Along with these fistulas, a new type of complex fistula in high outersphincteric space, a fistula at the roof of ischiorectal fossa inside the levator ani muscle (RIFIL), has been described. The diagnosis, management, and prognosis of RIFIL fistulas is reported to be even worse than supralevator and suprasphincteric fistulas. There is a lot of confusion regarding the anatomy, diagnosis, and management of these five types of fistulas. The main reason for this is the paucity of literature about these fistulas. The common feature of all these fistulas is their complete involvement of the external anal sphincter. Therefore, fistulotomy, the simplest and most commonly performed procedure, is practically ruled out in these fistulas and a sphincter-saving procedure needs to be performed. Recent advances have provided new insights into the anatomy, radiological modalities, diagnosis, and management of these five types of high fistulas. These have been discussed and guidelines formulated for the diagnosis and treatment of these fistulas for the first time in this paper.

Therapeutic efficacy of mesenchymal stem cells for abdominal aortic aneurysm: a meta-analysis of preclinical studies

Background

Abdominal aortic aneurysm (AAA) is life-threatening, surgical treatment is currently the only clinically available intervention for the disease. Mesenchymal stem cells (MSCs) have presented eligible immunomodulatory and regenerative abilities which showed favorable therapeutic efficacy in various cardiovascular diseases. However, current evidence summarizing the effectiveness of MSCs for AAA is lacking. Thus, a meta-analysis and systematic review was necessary to be performed to assess the therapeutic efficacy of MSCs for AAA in preclinical studies.

Methods

Comprehensive literature search restricted in English was conducted in PubMed, Cochrane Library, EBSCO, EMBASE and Web of Science from inception to Oct 2021. The primary outcomes were parameters about aortic diameter change during MSCs intervention. The secondary outcomes included elastin content and expression level of inflammatory cytokines, matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). Data were extracted and analyzed independently by two authors. The meta package with random effects model was used to calculate the pooled effect size and 95% confidence intervals in R (version 4.0.2).

Results

Meta-analysis of 18 included studies demonstrated that MSCs intervention has significant therapeutic effects on suppressing aortic diameter enlargement compared with the control group (diameter, SMD = − 1.19, 95% CI [− 1.47, − 0.91]; diameter change ratio, SMD = − 1.36, 95% CI [− 1.72, − 1.00]). Subgroup analysis revealed differences between MSCs and control group regarding to cell type, intervention route and cell compatibility. Moreover, the meta-analysis also showed that MSCs intervention had a significant effect on preserving aortic elastin content, reducing MCP-1, TNF-α, IL-6, MMP-2/9 and increasing TIMP-1/2 expression level compared with control group.

Conclusion

Our results suggested that MSC intervention is effective in AAA by suppressing aortic diameter enlargement, reducing elastin degradation, and modulating local immunoinflammatory reactions. These results are important for the systemic application of MSCs as a potential treatment candidate for AAA in further animal experiments and clinical trials.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02755-w.

Stem Cell Injection for Complex Refractory Perianal Fistulas in Crohn's Disease: A Single Center Initial Experience

From 30 to 70% of patients with Crohn's disease (CD) may develop perianal fistulas during their lifetime. The medical and surgical management of this complication is challenging, and its treatment still gives unsatisfactory results. However, recent studies on adipose-derived mesenchymal stem cells have proven their anti-inflammatory and immuno-modulatory potential, representing a new promising tool in the treatment of such stubborn disease. We report our initial experience with three patients who had recurrent perianal CD treated with local infiltration of stem cell darvadstrocel (Alofisel). All the patients had a long history of perianal disease refractory to multiple medical and surgical treatments. The preoperative workup included transperineal ultrasound (TP-US), pelvic MRI, and colonoscopy that ruled out active proctitis in all the patients. The post-treatment follow-up included clinical assessment at 1, 3, and 6 months with repeated MRI and TP-US at 6 months. At 6 months, 2 patients had a clinical response despite radiological persistence of fistula tracts, while one patient presented perianal fistula recurrence complicated by perianal abscess. Although our experience is limited to 3 patients and a short follow-up, our results confirm that darvadstrocel injection is a safe procedure, with a good clinical response in most of the patients, but that it apparently had no effect on the anatomical modification of the fistula tracts. Long-term results, with a rigorous assessment of anatomical lesions, are still needed to support the promising data of the literature.

A systematic review of the patient burden of Crohn’s disease-related rectovaginal and anovaginal fistulas

Background

Crohn’s disease (CD)-related rectovaginal fistulas (RVFs) and anovaginal fistulas (AVFs) are rare, debilitating conditions that present a substantial disease and treatment burden for women. This systematic literature review (SLR) assessed the burden of Crohn’s-related RVF and AVF, summarizing evidence from observational studies and highlighting knowledge gaps.

Methods

This SLR identified articles in PubMed and Embase that provide data and insight into the patient experience and disease burden of Crohn’s-related RVF and AVF. Two trained reviewers used pre-specified eligibility criteria to identify studies for inclusion and evaluate risk of bias using the Risk Of Bias In Non-randomized Studies of Interventions (ROBINS-I) tool for observational studies.

Results

Of the 582 records identified, 316 full-text articles were assessed, and 16 studies met a priori eligibility criteria and were included. Few epidemiology studies were identified, with one study estimating the prevalence of RVF to be 2.3% in females with Crohn’s disease. Seven of 12 treatment pattern studies reported that patients had or required additional procedures before and/or after the intervention of interest, demonstrating a substantial treatment burden. Seven of 11 studies assessing clinical outcomes reported fistula healing rates between 50 and 75%, with varying estimates based on population and intervention.

Conclusions

This SLR reports the high disease and treatment burden of Crohn’s-related RVF and AVF and identifies multiple evidence gaps in this field. The literature lacks robust, generalizable data, and demonstrates a compelling need for substantial, novel research into these rare and debilitating sequelae of CD.

Registration The PROSPERO registration number for the protocol for this systematic literature review is CRD42020177732.

Essential updates 2020/2021: Colorectal diseases (benign)—Current topics in the surgical and medical treatment of benign colorectal diseases

The development of new drugs for inflammatory bowel disease (IBD) is remarkable, and treatment strategies using multiple agents and various techniques are required; however, the treatment strategy is likely to be complex. Therefore, appropriate evaluation of traditional surgical treatment strategies and accurate knowledge of the efficacy and limitations of novel treatments are required. Total infectious complications were found to be associated with the use of corticosteroids and anti‐tumor necrosis factor‐α agents, but not with immunomodulators, anti‐integrin agents, and 5‐aminosalicylic acid. Regarding surgical procedures for IBD, conceived anastomosis methods, including Kono‐S for Crohn's disease stenosis, are associated with better outcomes than conventional techniques. Autologous cell transplantation for Crohn's fistulae has been shown to have a favorable outcome. Diverticulitis is increasing and will be treated more frequently in the future. Risk factors for the incidence of diverticulitis and differences in pathogenesis according to right or left side diverticulitis have been reported. Antibiotic therapy may be omitted for uncomplicated diverticulitis. Moreover, regarding surgical procedures, both bowel resection and anastomosis are associated with favorable short‐term outcomes, higher stoma closure rate, and superior medical economy compared to Hartmann's procedure. Risk factors for recurrence after diverticulitis surgery may provide better postoperative follow‐up. In this review, we explore the current topics of colorectal benign diseases, focusing on IBD and diverticulitis, based on clinical trials and meta‐analyses from 2020‐2021. This review consolidates the available knowledge and improves the quality of surgical procedures and perioperative management for IBD and diverticulitis.

Treatment of Inflammatory Bowel Disease: A Comprehensive Review

Inflammatory bowel disease (IBD), as a global disease, has attracted much research interest. Constant research has led to a better understanding of the disease condition and further promoted its management. We here reviewed the conventional and the novel drugs and therapies, as well as the potential ones, which have shown promise in preclinical studies and are likely to be effective future therapies. The conventional treatments aim at controlling symptoms through pharmacotherapy, including aminosalicylates, corticosteroids, immunomodulators, and biologics, with other general measures and/or surgical resection if necessary. However, a considerable fraction of patients do not respond to available treatments or lose response, which calls for new therapeutic strategies. Diverse therapeutic options are emerging, involving small molecules, apheresis therapy, improved intestinal microecology, cell therapy, and exosome therapy. In addition, patient education partly upgrades the efficacy of IBD treatment. Recent advances in the management of IBD have led to a paradigm shift in the treatment goals, from targeting symptom-free daily life to shooting for mucosal healing. In this review, the latest progress in IBD treatment is summarized to understand the advantages, pitfalls, and research prospects of different drugs and therapies and to provide a basis for the clinical decision and further research of IBD.

Regenerative medicine for digestive fistulae therapy: Benefits, challenges and promises of stem/stromal cells and emergent perspectives via their extracellular vesicles

Despite current management strategies, digestive fistulae remain extremely debilitating complications associated with significant morbidity and mortality, generating a need to develop innovative therapies in these indications. A number of clinical trials and experimental studies have thus investigated the potential of stem/stromal cells (SCs) or SC-derived extracellular vesicles (EVs) administration for post-surgical and Crohn's-associated fistulae. This review summarizes the physiopathology and current standards-of-care for digestive fistulae, along with relevant evidence from animal and clinical studies regarding SC or EV treatment for post-surgical digestive fistulae. Additionally, existing preclinical models of fistulizing Crohn's disease and results of SC therapy trials in this indication will be presented. The optimal formulation and administration protocol of SC therapy products for gastrointestinal fistula treatment and the challenges for a widespread use of darvadstrocel (Alofisel) in clinical practice will be discussed. Finally, the potential advantages of EV therapy and the obstacles towards their clinical translation will be introduced.

Treatments for the amelioration of persistent factors in complex anal fistula

Anal fistulae are abnormal hollow connections between the wall of the anal canal and the perianal skin around the anus that have remained a burden on the medical sector for centuries. The complexity of this disease is attributed to a number of factors such as the degree of associated sphincter muscle, concomitant illnesses, existence of multiple fistulous tracts and the number of previous interventions. Persistence of a complex anal fistula can cause a decline in patient's physical quality of life as well as impact on the psychological status of patients who often suffer from anxiety and depression. Surgical intervention remains the gold standard for treatment, however; the risk of incontinence and high recurrence potential has led to interest into developing alternative treatment approaches such as the use of biologics, bioactives and biomaterials. One potential reason for these varied outcomes could be the multifactorial interplay between genetic, immune-related, environmental, and microbial persistence factors on tissue regeneration. Recent observations have proposed that adverse inflammatory mediators may contribute more than microbial factors. The moderate to high success rates of biotechnological advances (mesenchymal stem cells and biomaterial scaffolds) show promise as therapies for the amelioration of adverse persistent factors while facilitating a means to closing the fistula tract. The purpose of this review is to outline recent advances in biologics and combination therapies to treat persistent factors associated with complex anal fistula.

Current Overview on the Use of Mesenchymal Stem Cells for Perianal Fistula Treatment in Patients with Crohn's Disease

Perianal fistula in patients with Crohn’s disease is an extremely challenging condition. The disease tends to reoccur, and with current treatment options, a large number of patients are left with active ailment and experience major morbidity. In recent years, hopeful results regarding local use of mesenchymal stem cells (MSCs) in perianal Crohn’s disease have been published. Although to this day there are no clear guidelines determining optimal dosage, injections frequency and culture conditions, their efficiency has proven to be much higher than conventionally used methods. According to studies, they can effectively induce as well as maintain fistula closure. This approach also avoids common side effects related to conventional surgical treatment.

Stem Cell Therapy For The Treatment Of Crohn's Disease; Current Obstacles And Future Hopes. (Mini-Review)

BACKGROUND

Crohn's disease (CD) is an autoimmune disease of the gastrointestinal tract, characterized by relapsing and remitting courses. The disease is debilitating in nature with three prominent phenotypic clinical presentations; fistulizing, stenosing, and inflammatory. Stem cells offer a new hope for CD patients with modifying the immune response and progression of the healing process.

AIM

This mini-review discusses the role of stem cells in treating CD, their effectiveness as a new therapy and their current limitations faced.

METHODS

The author conducted a literature review on recent randomized controlled trials and cohort studies concerned with the topic in question using the following keywords (Crohn's Disease, perianal fistula, Stem cell therapy, mesenchymal stem cells, remission).

RESULTS

Clinical trials show that the stem cells are more effective in the CD associated complex perianal fistula than the CD enteritis. Till the time being, there are no standardized guidelines regarding; dose of stem cells used, number of doses administered, route of administration, type of stem cells used. Only one group of researchers proposed a standardized procedure for injecting mesenchymal stem cells in complex perianal fistula, according to their own experience in clinical trials. Moreover, mesenchymal stem cells and their related types (placental, adipose tissue, umbilical tissue, etc.) are the most safe and effective in clinical trials. Currently; the commercially available mesenchymal stem cells preparation (Darvadstrocel (Cx601)) is the only one approved by The United States Food and Drug Administration (FDA) for clinical use in refractory CD associated complex perianal fistula.

CONCLUSIONS

Stem cell therapy (SCT) shows promise in; inducing remission in refractory Crohn's colitis, and perianal fistula, but further research is required before SCT could be applied to clinical practice guidelines.

MSC therapy for inflammatory bowel disease

Inflammatory bowel disease (IBD) belongs to the group of diseases characterized by idiopathic inflammation of the digestive tract organs. Two basic IBD types are distinguished: ulcerative colitis and Crohns disease. The IBD symptoms including vomiting and diarrhea, abdominal pain, rectal bleeding, anemia have a significant negative impact on the general patients state of health. Besides, IBD patients are susceptible to the risk of a number of serious diseases such as colorectal cancer, thrombosis and primary sclerosing cholangitis. More than 4 million people in the USA and Europe suffer from IBD, with 70000 new cases diagnosed yearly in the USA only. In some cases, a surgical removal of the damaged digestive tract fragments is required to treat severe IBD forms. However, drug therapy of IBD has mainly been used in the last decades. The rate of remission with application of traditional IBD therapy is estimated as 20-30%, and is still no higher than 50% with the combined therapy. Cell therapy has been proven to be a very promising approach in the IBD treatment. In our review, we discuss mesenchymal stromal cells (MSC) and the most important preclinical and clinical results of their application for the IBD therapy.

Indeterminate Colitis - Update on Treatment Options

Indeterminate colitis (IC) is described in approximately 5-15% of patients with inflammatory bowel disease (IBD). It usually reflects a difficulty or lack of clarity in distinguishing between ulcerative colitis (UC) and Crohn's disease (CD) on biopsy or colectomy specimens. The diagnostic difficulty may explain the variability in the reported prevalence and incidence of IC. Clinically, most IC patients tend to evolve over time to a definite diagnosis of either UC or CD. IC has also been interchangeably described as inflammatory bowel disease unclassified (IBDU). This review offers an overview of the available limited literature on the conventional medical and surgical treatments for IC. In contrast to the numerous studies on the medical management of UC and CD, there are very few data from dedicated controlled trials on the treatment of IC. The natural evolution of IC more closely mimics UC. Regarding medical options for treatment, most patients diagnosed with IC are treated similarly to UC, and treatment choices are based on disease severity. Others are managed similarly to CD if there are features suggestive of CD, including fissures, skin tags, or rectal sparing. In medically refractory IC, surgical treatment options are limited and include total proctocolectomy (TPC) and ileal pouch-anal anastomosis (IPAA), with its associated risk factors and complications. Post-surgical complications and pouch failure rates were historically thought to be more common in IC patients, but recent meta-analyses reveal similar rates between UC and IC patients. Future therapies in IBD are focused on known mechanisms in the disease pathways of UC and CD. Owing to the lack of IC-specific studies, clinicians have traditionally and historically extrapolated the data to IC patients based on their symptomatology, clinical course, and endoscopic findings.