Long-Term Follow-Up of Crohn Disease Fistulas After Local Injections of Bone Marrow-Derived Mesenchymal Stem Cells

Comparison of different sources of mesenchymal stem cells: focus on inflammatory bowel disease

Inflammatory bowel disease (IBD) poses a significant challenge in modern medicine, with conventional treatments limited by efficacy and associated side effects, necessitating innovative therapeutic approaches. Mesenchymal stem cells (MSC) have emerged as promising candidates for IBD treatment due to their immunomodulatory properties and regenerative potential. This thesis aims to explore and compare various sources of MSC and evaluate their efficacy in treating IBD. This study comprehensively analyses MSC derived from multiple sources, including bone marrow, adipose tissue, umbilical cord, and other potential reservoirs. Core elements of this investigation include assessing differences in cell acquisition, immunomodulatory effects, and differentiation capabilities among these MSC sources, as well as comparing their clinical trial outcomes in IBD patients to their therapeutic efficacy in animal models. Through meticulous evaluation and comparative analysis, this thesis aims to elucidate disparities in the efficacy of different MSC sources for IBD treatment, thereby identifying the most promising therapeutic applications. The findings of this study are intended to advance our understanding of MSC biology and offer valuable insights for selecting the most effective MSC sources for personalized IBD therapy. Ultimately, this research endeavor will optimise therapeutic strategies for managing inflammatory bowel disease through the utilization of MSC.

Extracellular vesicles derived from bovine adipose-derived mesenchymal stromal cells enhance in vitro embryo production from lesioned ovaries

BACKGROUND AND AIMS

Ovum pick-up (OPU) is an intrinsic step of in vitro fertilization procedures. Nevertheless, it can cause ovarian lesions and compromise female fertility in bovines. Recently, we have shown that intraovarian injection of adipose-derived mesenchymal stromal cells (AD-MSCs) effectively preserves ovarian function in bovines. Given that MSC-derived extracellular vesicles (MSC-EVs) have been shown to recapitulate several therapeutic effects attributed to AD-MSCs and that they present logistic and regulatory advantages compared to AD-MSCs, we tested whether MSC-EVs would also be useful to treat OPU-induced lesions.

METHODS

MSC-EVs were isolated from the secretome of bovine AD-MSCs, using ultrafiltration (UF) and ultracentrifugation methods. The MSC-EVs were characterized according to concentration and mean particle size, morphology, protein concentration and EV markers, miRNA, mRNA, long noncoding RNA profile, total RNA yield and potential for induction of the proliferation and migration of bovine ovarian stromal cells. We then investigated whether intraovarian injection of MSC-EVs obtained by UF would reduce the negative effects of acute OPU-induced ovarian lesions in bovines. To do so, 20 animals were divided into 4 experimental groups (n = 5), submitted to 4 OPU cycles and different experimental treatments including vehicle only (G1), MSC-EVs produced by 7.5 × 106 AD-MSCs (G2), MSC-EVs produced by 2.5 × 106 AD-MSCs (G3) or 3 doses of MSC-EVs produced by 2.5 × 106 AD-MSCs, injected after OPU sessions 1, 2 and 3 (G4).

RESULTS

Characterization of the MSC-EVs revealed that the size of the particles was similar in the different isolation methods; however, the UF method generated a greater MSC-EV yield. MSC-EVs processed by both methods demonstrated a similar ability to promote cell migration and proliferation in ovarian stromal cells. Considering the higher yield and lower complexity of the UF method, UF-MSC-EVs were used in the in vivo experiment. We evaluated three therapeutic regimens for cows subjected to OPU, noting that the group treated with three MSC-EV injections (G4) maintained oocyte production and increased in vitro embryo production, compared to G1, which presented compromised embryo production following the OPU-induced lesions.

CONCLUSIONS

MSC-EVs have beneficial effects both on the migration and proliferation of ovarian stromal cells and on the fertility of bovines with follicular puncture injury in vivo.

The Role of Adipose Tissue Mesenchymal Stem Cells in Colonic Anastomosis Healing in Inflammatory Bowel Disease: Experimental Study in Rats

(1) Background: A surgical operation on an inflamed bowel is, diachronically, a challenge for the surgeon, especially for patients with inflammatory bowel disease. Adipose tissue-derived mesenchymal stromal cells are already in use in clinical settings for their anti-inflammatory properties. The rationale of the current study was to use AdMSCs in high-risk anastomoses to monitor if they attenuate inflammation and prevent anastomotic leak. (2) Methods: a total of 4 groups of rats were subjected to a surgical transection of the large intestine and primary anastomosis. In two groups, DSS 5% was administered for 7 days prior to the procedure, to induce acute intestinal inflammation. After the anastomosis, 5 × 106 autologous AdMSCs or an acellular solution was injected locally. Macroscopic evaluation, bursting pressure, hydroxyproline, and inflammatory cytokine expression were the parameters measured on the 8th post-operative day. (3) Results: Significantly less intra-abdominal complications, higher bursting pressures, and a decrease in pro-inflammatory markers were found in the groups that received AdMSCs. No difference in VEGF expression was observed on the 8th post-operative day. (4) Conclusions: AdMSCs attenuate inflammation in cases of acutely inflamed anastomosis.

FISTULIZING PERIANAL CROHN'S DISEASE: IS THE PATIENT'S SEX A BURDEN? A SYSTEMATIC REVIEW

BACKGROUND

Fistulizing perianal Crohn's disease poses a treatment challenge, and researchers postulate that this phenotype in young male patients could have a worst outcome.

OBJECTIVE

Thus, the aim of this study was to assess whether sex influences the response to treatment for these patients.

METHODS

This systematic review (PROSPERO CRD42022319629) was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. We selected articles published in English, Spanish, Portuguese, and Italian between 2010 and 2020 in the PubMed and Science Direct databases. According to the PICO acronym, prospective studies in patients older than 18 years with the objective of treating fistulizing perianal Crohn's disease were selected. Studies in pediatric populations, retrospective, without treatment objectives, and that included only rectovaginal fistulas or a single sex were excluded. Study quality was assessed using the Cochrane risk of bias tool and Newcastle-Ottawa scale.

RESULTS

Of the 1887 articles found, 33 were included. Most studies used anti-TNF drugs as treatment (n=11). Ten studies had subgroup analyses; of them, the two studies reporting sex differences used infliximab and adalimumab as treatment and showed that women had a longer fistula closure time than men.

CONCLUSION

This systematic review showed that few data corroborate the difference between sexes in the treatment of fistulizing perianal Crohn's disease, possibly having a greater relationship with the phenotype. However, considering the lack of results, further studies with this objective and with standardization of fistulas and response assessment methods are needed.

Short-Term Clinical Response and Changes in the Fecal Microbiota and Metabolite Levels in Patients with Crohn's Disease After Stem Cell Infusions

Recent studies have shown a close relationship between the gut microbiota and Crohn's disease (CD). This study aimed to determine whether mesenchymal stem cell (MSC) treatment alters the gut microbiota and fecal metabolite pathways and to establish the relationship between the gut microbiota and fecal metabolites. Patients with refractory CD were enrolled and received 8 intravenous infusions of MSCs at a dose of 1.0 × 106 cells/kg. The MSC efficacy and safety were evaluated. Fecal samples were collected, and their microbiomes were analyzed by 16S rDNA sequencing. The fecal metabolites at baseline and after 4 and 8 MSC infusions were identified by liquid chromatography-mass spectrometry (LC--MS). A bioinformatics analysis was conducted using the sequencing data. No serious adverse effects were observed. The clinical symptoms and signs of patients with CD were substantially relieved after 8 MSC infusions, as revealed by changes in weight, the CD activity index (CDAI) score, C-reactive protein (CRP) level, and erythrocyte sedimentation rate (ESR). Endoscopic improvement was observed in 2 patients. A comparison of the gut microbiome after 8 MSC treatments with that at baseline showed that the genus Cetobacterium was significantly enriched. Linoleic acid was depleted after 8 MSC treatments. A possible link between the altered Cetobacterium abundance and linoleic acid metabolite levels was observed in patients with CD who received MSCs. This study enabled an understanding of both the gut microbiota response and bacterial metabolites to obtain more information about host-gut microbiota metabolic interactions in the short-term response to MSC treatment.

Stem Cell Therapy in Inflammatory Bowel Disease: A Review of Achievements and Challenges

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is a group of chronic inflammatory diseases of the gastrointestinal tract. Repeated inflammation can lead to complications, such as intestinal fistula, obstruction, perforation, and bleeding. Unfortunately, achieving durable remission and mucosal healing (MH) with current treatments is difficult. Stem cells (SCs) have the potential to modulate immunity, suppress inflammation, and have anti-apoptotic and pro-angiogenic effects, making them an ideal therapeutic strategy to target chronic inflammation and intestinal damage in IBD. In recent years, hematopoietic stem cells (HSCs) and adult mesenchymal stem cells (MSCs) have shown efficacy in treating IBD. In addition, numerous clinical trials have evaluated the efficiency of MSCs in treating the disease. This review summarizes the current research progress on the safety and efficacy of SC-based therapy for IBD in both preclinical models and clinical trials. We discuss potential mechanisms of SC therapy, including tissue repair, paracrine effects, and the promotion of angiogenesis, immune regulation, and anti-inflammatory effects. We also summarize current SC engineering strategies aimed at enhancing the immunosuppressive and regenerative capabilities of SCs for treating intestinal diseases. Additionally, we highlight current limitations and future perspectives of SC-related therapy for IBD.

Use of Mesenchymal Stem Cells in Crohn's Disease and Perianal Fistulas: A Narrative Review

Crohn's Disease (CD), which usually leads to anal fistulas among patients, is the most important inflammatory bowel disease that causes morbidity in many people around the world. This review article proposes using MSCs as a hopeful therapeutic strategy for CD and anal fistula treatment in both preclinical and clinical conditions. Finally, darvadstrocel, a cell-based medication to treat complex anal fistulas in adults, as the only European Medicines Agency (EMA)-approved product for the treatment of anal fistulas in CD is addressed. Although several common therapies, such as surgery and anti-tumor necrosis factor-alpha (TNF-α) drugs as well as a combination of these methods is used to improve this disease, however, due to the low effectiveness of these treatments, the use of new strategies with higher efficiency is still recommended. Cell therapy is among the new emerging therapeutic strategies that have attracted great attention from clinicians due to its unique capabilities. One of the most widely used cell sources administrated in cell therapy is mesenchymal stem cell (MSC). This review article will discuss preclinical and clinical studies about MSCs as a potent and promising therapeutic option in the treatment of CD and anal fistula.

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.

Mechanisms of mucosal healing: treating inflammatory bowel disease without immunosuppression?

Almost all currently available treatments for inflammatory bowel disease (IBD) act by inhibiting inflammation, often blocking specific inflammatory molecules. However, given the infectious and neoplastic disease burden associated with chronic immunosuppressive therapy, the goal of attaining mucosal healing without immunosuppression is attractive. The absence of treatments that directly promote mucosal healing and regeneration in IBD could be linked to the lack of understanding of the underlying pathways. The range of potential strategies to achieve mucosal healing is diverse. However, the targeting of regenerative mechanisms has not yet been achieved for IBD. Stem cells provide hope as a regenerative treatment and are used in limited clinical situations. Growth factors are available for the treatment of short bowel syndrome but have not yet been applied in IBD. The therapeutic application of organoid culture and stem cell therapy to generate new intestinal tissue could provide a novel mechanism to restore barrier function in IBD. Furthermore, blocking key effectors of barrier dysfunction (such as MLCK or damage-associated molecular pattern molecules) has shown promise in experimental IBD. Here, we review the diversity of molecular targets available to directly promote mucosal healing, experimental models to identify new potential pathways and some of the anticipated potential therapies for IBD.

Mechanisms of mucosal healing: treating inflammatory bowel disease without immunosuppression?

Almost all currently available treatments for inflammatory bowel disease (IBD) act by inhibiting inflammation, often blocking specific inflammatory molecules. However, given the infectious and neoplastic disease burden associated with chronic immunosuppressive therapy, the goal of attaining mucosal healing without immunosuppression is attractive. The absence of treatments that directly promote mucosal healing and regeneration in IBD could be linked to the lack of understanding of the underlying pathways. The range of potential strategies to achieve mucosal healing is diverse. However, the targeting of regenerative mechanisms has not yet been achieved for IBD. Stem cells provide hope as a regenerative treatment and are used in limited clinical situations. Growth factors are available for the treatment of short bowel syndrome but have not yet been applied in IBD. The therapeutic application of organoid culture and stem cell therapy to generate new intestinal tissue could provide a novel mechanism to restore barrier function in IBD. Furthermore, blocking key effectors of barrier dysfunction (such as MLCK or damage-associated molecular pattern molecules) has shown promise in experimental IBD. Here, we review the diversity of molecular targets available to directly promote mucosal healing, experimental models to identify new potential pathways and some of the anticipated potential therapies for IBD.

Choosing the right biologic for complications of inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease (IBD) is a chronic, inflammatory condition that involves the intestinal tract, and can also present with extra-intestinal manifestations (EIM). Choosing the right treatment for IBD is often nuanced and decisions can become even more complicated when a patient presents with or develops a complication of the disease.

AREAS COVERED

We aimed to provide an overview of the most common complications of IBD, specifically intestinal and EIM, and summarize the data regarding biologic therapy for treatment of these conditions. A comprehensive literature review was performed using PubMed and Medline databases to identify studies published in the English language relevant to the broad scope of this review.

EXPERT OPINION

There are still significant gaps in our understanding of the pathophysiology of IBD and its treatment, especially in regards to complications of the disease. As novel therapies continue to emerge for treatment of IBD, we feel concurrent examination of their impact on intestinal complications and EIM of IBD is important and should be a priority of future research.

Three-year outcome of local injection of autologous stromal vascular fraction cells and microfat in refractory perianal fistulas of Crohn's disease

Perianal fistulas in Crohn's disease are frequent and disabling, with a major impact on patients' quality of life. Cell-based therapy using mesenchymal stem cells represents new hope for these patients, but long-term efficacy remains challenging. In a pilot study, including patients with refractory complex perianal fistulas, autologous adipose-derived stromal vascular fraction (ADSVF) combined with microfat achieved combined remission in 60% of cases, with a good safety profile at 1 year. The purpose of this study is to assess whether these results were maintained at longer term. The safety and efficacy data of the ten patients were evaluated retrospectively 3 years after injection on the basis of clinical and radiological data. MRI were analysed according to the MAGNIFI-CD score. No adverse event was attributed to the experimental stem-cell treatment. Combined remission was achieved in 7 patients (70%) and associated with a significant improvement in the MAGNIFI-CD MRI score. In conclusion, the safety and efficacy of ADSVF and microfat injection in Crohn's disease fistulas were maintained at 3 years, demonstrating that this innovative strategy is effective in producing a long-lasting healing effect. The ongoing multicentre randomized placebo-controlled trial (NCT04010526) will be helpful to define the place for this approach in the current therapeutic arsenal.

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.

A recent update on the use of Chinese medicine in the treatment of inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic idiopathic disease that is characterized by inflammation of the gastrointestinal tract. Proper management of IBD requires both early diagnosis and novel therapies and management programs. Many reports have suggested that Chinese medicine has unique properties favorable to the treatment of IBD. However, there are no systematic analyses on this topic.

PURPOSE

This review summarizes recent studies that assessed the effects and mechanisms of Chinese medicine in the treatment of IBD in order to fully understand the advantages of Chinese medicine in the management of IBD.

METHODS

A literature search was conducted using peer-reviewed and clinical databases, including PubMed, Web of Science, ClinicalTrials.gov, MEDLINE, EMBASE, Springer LINK, Wan-fang database, the Chinese Biomedicine Database, and the China National Knowledge Infrastructure (CNKI). Keywords used were inflammatory bowel disease (including Ulcerative colitis or Crohn's disease) and Chinese medicine. All selected articles were from 1997 to 2021, and each were assessed critically for our exclusion criteria. Studies describing the pathogenesis of IBD, the effects and mechanisms of Chinese medicine in the treatment of IBD, in particular their roles in immune regulation, intestinal flora regulation, and improvement of intestinal barrier function, were included.

CONCLUSION

This review highlights recent progress in the use of Chinese medicine in the treatment of IBD. It also provides a reference for further evaluation and exploration of the potential of classical multi-herbal Chinese medicine in the treatment of IBD.

Approach to medical therapy in perianal Crohn's disease

Perianal Crohn's disease remains a challenging condition to treat and can have a substantial negative impact on quality of life. It often requires combined surgical and medical interventions. Anti-tumor necrosis factor (anti-TNF) therapy, including infliximab and adalimumab, remain preferred medical therapies for perianal Crohn's disease. Infliximab has been shown to be efficacious in improving fistula closure rates in randomized controlled trials. Clinicians can be faced with a number of questions relating to the optimal use of anti-TNF therapy in perianal Crohn's disease. Specific issues include evaluation for the presence of perianal sepsis, the treatment target of therapy, the ideal time to commence treatment, whether additional medical therapy should be used in conjunction with anti-TNF therapy, and the duration of treatment. This article will discuss key studies which can assist clinicians in addressing these matters when they are considering or have already commenced anti-TNF therapy for the treatment of perianal Crohn's disease. It will also discuss current evidence regarding the use of vedolizumab and ustekinumab in patients who are failing to achieve a response to anti-TNF therapy for perianal Crohn's disease. Lastly, new therapies such as local injection of mesenchymal stem cell therapy will be discussed.

Mesenchymal stem/stromal cells as a valuable source for the treatment of immune-mediated disorders

Over recent years, mesenchymal stem/stromal cells (MSCs) and their potential biomedical applications have received much attention from the global scientific community in an increasing manner. Firstly, MSCs were successfully isolated from human bone marrow (BM), but in the next steps, they were also extracted from other sources, mostly from the umbilical cord (UC) and adipose tissue (AT). The International Society for Cellular Therapy (ISCT) has suggested minimum criteria to identify and characterize MSCs as follows: plastic adherence, surface expression of CD73, D90, CD105 in the lack of expression of CD14, CD34, CD45, and human leucocyte antigen-DR (HLA-DR), and also the capability to differentiate to multiple cell types including adipocyte, chondrocyte, or osteoblast in vitro depends on culture conditions. However, these distinct properties, including self-renewability, multipotency, and easy accessibility are just one side of the coin; another side is their huge secretome which is comprised of hundreds of mediators, cytokines, and signaling molecules and can effectively modulate the inflammatory responses and control the infiltration process that finally leads to a regulated tissue repair/healing or regeneration process. MSC-mediated immunomodulation is a direct result of a harmonic synergy of MSC-released signaling molecules (i.e., mediators, cytokines, and chemokines), the reaction of immune cells and other target cells to those molecules, and also feedback in the MSC-molecule-target cell axis. These features make MSCs a respectable and eligible therapeutic candidate to be evaluated in immune-mediated disorders, such as graft versus host diseases (GVHD), multiple sclerosis (MS), Crohn's disease (CD), and osteoarthritis (OA), and even in immune-dysregulating infectious diseases such as the novel coronavirus disease 2019 (COVID-19). This paper discussed the therapeutic applications of MSC secretome and its biomedical aspects related to immune-mediated conditions. Sources for MSC extraction, their migration and homing properties, therapeutic molecules released by MSCs, and the pathways and molecular mechanisms possibly involved in the exceptional immunoregulatory competence of MSCs were discussed. Besides, the novel discoveries and recent findings on immunomodulatory plasticity of MSCs, clinical applications, and the methods required for their use as an effective therapeutic option in patients with immune-mediated/immune-dysregulating diseases were highlighted.

Intestinal Stem Cells and Immune Cell Relationships: Potential Therapeutic Targets for Inflammatory Bowel Diseases

The mammalian intestine is the largest immune organ that contains the intestinal stem cells (ISC), differentiated epithelial cells (enterocytes, Paneth cells, goblet cells, tuft cells, etc.), and gut resident-immune cells (T cells, B cells, dendritic cells, innate lymphoid cell, etc.). Inflammatory bowel disease (IBD), a chronic inflammatory disease characterized by mucosa damage and inflammation, threatens the integrity of the intestine. The continuous renewal and repair of intestinal mucosal epithelium after injury depend on ISCs. Inflamed mucosa healing could be a new target for the improvement of clinical symptoms, disease recurrence, and resection-free survival in IBD treated patients. The knowledge about the connections between ISC and immune cells is expanding with the development of in vitro intestinal organoid culture and single-cell RNA sequencing technology. Recent findings implicate that immune cells such as T cells, ILCs, dendritic cells, and macrophages and cytokines secreted by these cells are critical in the regeneration of ISCs and intestinal epithelium. Transplantation of ISC to the inflamed mucosa may be a new therapeutic approach to reconstruct the epithelial barrier in IBD. Considering the links between ISC and immune cells, we predict that the integration of biological agents and ISC transplantation will revolutionize the future therapy of IBD patients.

Efficacy and Safety of Mesenchymal Stem/Stromal Cell Therapy for Inflammatory Bowel Diseases: An Up-to-Date Systematic Review

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gut that can lead to severe gastrointestinal symptoms, malnutrition, and complications such as fistulas and cancer. Mesenchymal stem/stromal cells (MSCs) are being investigated as a novel therapy for IBD and have been demonstrated to be safe and effective for perianal fistulizing Crohn’s disease (PFCD). This systematic review aims to present the most recent studies on the safety and efficacy of MSC therapy in IBD. A detailed search strategy of clinical trials on MSCs and IBD was performed on PubMed, with 32 studies selected for inclusion in this review. The newest studies on local MSC injection for PFCD continue to support long-term efficacy while maintaining a favorable safety profile. The evidence for systemic MSC infusion in luminal IBD remains mixed due to marked methodological heterogeneity and unclear safety profiles. Although further studies are needed to better establish the role of this novel treatment modality, MSCs are proving to be a very exciting addition to the limited therapies available for IBD.

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

BACKGROUND

Fistulas have puzzled us all the time and stem cell therapy for it is still in its infancy. We conducted a meta-analysis and systematic review to evaluate the efficacy of stem cells and its potential mechanisms in the management of Crohn's fistula.

METHODS

Electronic databases were searched comprehensively for studies reporting the efficacy and safety of stem cells in patients with any form of Crohn's fistula. A random-effects model was used, and all outcomes were calculated by SPSS 24.0.

RESULTS

Twenty-nine articles with 1252 patients were included. It showed that stem cell group had a higher rate of fistula healing compared to placebo group in patients of Crohn's fistula (61.75% vs 40.46%, OR 2.21, 95% CI 1.19 to 4.11, P < 0.05). 3 × 10⁷ cells/mL stem cell (SC) group had an advantage in fistula healing rate with 71.0% compared to other doses group of stem cells (RR 1.3, 95% CI 0.76 to 2.22). And the healing rates of patients with perianal and transsphincteric fistulas (77.95%, 76.41%) were higher than those with rectovaginal fistulas. It was an amazing phenomenon that CDAI and PDAI scores occurred an obviously transient rise with the use of stem cells after 1 month (both of P < 0.05), while they returned to the baseline level by giving stem cells 3 months later. Furthermore, the incidence rate of treatment-related adverse events in the stem cell group was significantly lower than in the placebo group (RR 0.58, 95% CI 0.30 to 1.14).

CONCLUSIONS

Our study has highlighted that stem cells was a promising method in the treatment of Crohn's fistula based on its higher efficacy and lower incidence of adverse events, especially ADSCs and Cx601. While it also needs more clinical and pre-clinical studies to strengthen evidences in the future.

The therapeutic efficacy of mesenchymal stromal cells on experimental colitis was improved by the IFN-γ and poly(I:C) priming through promoting the expression of indoleamine 2,3-dioxygenase

BACKGROUND

Inflammatory bowel disease is a chronic and excessive inflammation of the colon and small intestine. We previously reported that priming of mesenchymal stromal cells (MSCs) with poly(I:C) induced them to express indoleamine 2,3-dioxygenase (IDO). We tried to find out whether the IFN-γ and poly(I:C)-primed MSCs have better therapeutic efficacy on the experimental colitis in the IDO1-dependent manner.

METHODS

To compare the therapeutic effects between the unstimulated MSCs and primed MSCs on murine colitis, mice (C57BL6) were administered with 2.5% dextran sodium sulfate (DSS) in drinking water for 5 days and injected with MSCs intraperitoneally on days 1 and 3 following DSS ingestion. The disease activity index score and body weight loss were assessed daily until day 9.

RESULTS

Mice receiving the IFN-γ and poly(I:C)-primed MSCs showed a reduced disease activity index and less weight loss. Colon tissue from the same mice presented attenuated pathological damage, increased Paneth cells, increased IDO1-expressing cells, and better proliferation of enterocytes. The primed MSC treatment upregulated the mRNA expression of intestinal stem cell markers (Lgr5, Olfm4, and Bmi1), enterocyte differentiation markers (Muc2, Alpi, Chga, and occludin), and regulatory T (Treg) cells (Foxp3). The same treatment decreased inflammatory cell infiltration to lymphoid organs and the level of pro-inflammatory cytokines (IL-1β, TNF-α, IL-6, and MCP-1) in colon tissue. Notably, in vivo pharmacologic inhibition of the IDO1 activity blocked the Foxp3 upregulation in colon tissue and diminished the protective effects of the primed MSC.

CONCLUSIONS

The priming of MSCs with the IFN-γ and poly(I:C) is a promising new strategy to improve the therapeutic efficacy of MSC and is worth further research.

Developing cell therapies as drug products

In the last 20 years, the global regulatory frameworks for drug assessment have been managing the challenges posed by using cellular products as new therapeutic tools. Currently, they are defined as "Advanced Therapy Medicinal Products", comprising a large group of cellular types that either alone or in combination with gene and tissue engineering technology. They have the potential to change the natural course of still lethal or highly debilitating diseases, including cancers, opportunistic infections and chronic inflammatory conditions. Globally, more than 50 cell-based products have obtained market authorization. This overview describes the advantages and unsolved challenges on developing cells as innovative therapeutic vehicles. The main cell therapy players and the legal framework are discussed, starting from chimeric antigen receptor T-cells for leukaemia and solid tumours, dealing then with lymphocytes as potent anti-microbiological tools and then focusing on mesenchymal stem/stromal cells whose role covers regenerative medicine, immunology and anti-tumour therapy.

The Immune System and Its Contribution to Variability in Regenerative Medicine

The immune system plays a critical role in directing tissue repair and regeneration outcomes. Tissue engineering technologies that are designed to promote new tissue growth will therefore be impacted by immune factors that are present in patients both locally at the site of intervention and systemically. The immune state of patients can be influenced by many factors, including infection, nutrition, and other disease comorbidities. As a result, the immune state is highly variable and may be a source of variability in tissue-engineered products in the clinic, which is not found in preclinical models. In this review, we will summarize key immune cells and evidence of their activity in tissue repair and potential in tissue engineering systems. We also discuss how clinical translation of tissue engineering strategies, in particular stem cells, helped elucidate the importance of the immune system. With increased understanding of the immune system's role in repair and tissue engineering systems, it will likely become a therapeutic target and component of future therapies.

Mesenchymal Stromal Cell Therapy in the Management of Perianal Fistulas in Crohn's Disease: An Up-To-Date Review

Crohn’s Disease (CD) is a chronic inflammatory disorder that potentially involves the entire gastrointestinal tract. Perianal fistulizing CD (pCD) is a serious and frequent complication associated with significant morbidities and a heavy negative impact on quality of life. The aim of CD treatment is to induce and maintain disease remission and to promote mucosal repair. Unfortunately, even the best therapeutic regimens in pCD do not have long-term efficacy and cause a significant number of side effects. Therefore, it is mandatory to study new therapeutical options such as the use of mesenchymal stromal cells (MSCs). These cells promote tissue repair via the induction of immunomodulation. The present review aims to analyze the existing updated scientific literature on MSCs adoption in the treatment of pCD to evaluate its efficacy and safety and to compare the use of bone marrow and adipose tissue derived MSCs, type of administration, and dose required for recovery.

CELL THERAPY IN INFLAMMATORY BOWEL DISEASE

In recent years, cell-based therapies have been explored in various immune-mediated inflammatory diseases, including inflammatory bowel disease (IBD). Cell therapy is the process of introducing new cells into an organism or tissue in order to treat a disease. The most studied cellular treatment in IBD was "stem cells-based therapy", which was explored according to different protocols in terms of type of donors, stem cells sources, study design and clinical endpoints. More recently, preliminary studies have also described the clinical use of "regulatory cells", which include T-reg and Tr1 cells, and "tolerogenic" dendritic cells. Finally, induced pluripotent stem cells are the subject of an intensive preclinical research program on animal models, including those related to colitis.

Spatio-Temporal Metabolokinetics and Efficacy of Human Placenta-Derived Mesenchymal Stem/Stromal Cells on Mice with Refractory Crohn's-like Enterocutaneous Fistula

Crohn's disease (CD) with externally fistulizing openings indicates the aggressive and relapsing manifestation and results in undesirable long-term outcomes of patients. MSC-based approach combined with multidisciplinary strategy has mandated a redefinition of the administration and management of numerous recurrent and refractory diseases whereas the spatio-temporal evaluation of the metabolokinetics and efficacy of MSCs on intractable CD with enterocutaneous fistula (EF) are largely inaccessible and dauntingly complex. Herein, we primitively established dual-fluorescence expressing placenta-derived MSCs (DF-MSCs) and explored their multidimensional attributes, including cytomorphology, immunophenotying, multilineage differentiation and long-term proliferation, together with the recognition of bifluorescence intensity (BLI). Then, with the aid of in vivo living imaging, clinicopathological or inflammatory cytokine examinations and in vitro analyses, we systematically and meticulously dissected the metabolokinetics and curative effect of MSCs on mice with refractory Crohn's-like EF (EF mice), together with revealing the underlying mechanism including reactive oxygen species (ROS) and neovascularization. Strikingly, the DF-MSCs exhibited stabilized BLI and biological properties. The spatio-temporal distribution and therapeutic process of MSCs in EF mice were intuitively delineated. Meanwhile, our data indicated the curative mechanisms of DF-MSCs by simultaneously downregulating ROS and accelerating neovascularization. Collectively, we systematically illuminated the spatio-temporal biofunction and mechanism of DF-MSCs on EF mice. Our findings have supplied new references for safety and effectiveness assessments as well as the establishment of guidelines for optimal administrations of MSC-based cytotherapy in preclinical studies, which collectively indicates the prospect of P-MSC administration in clinical trials during a wide spectrum of disease remodeling including the fistulizing CD. Graphical abstract.

From Cancer to Immune-Mediated Diseases and Tolerance Induction: Lessons Learned From Immune Oncology and Classical Anti-cancer Treatment

Success in cancer treatment over the last four decades has ranged from improvements in classical drug therapy to immune oncology. Anti-cancer drugs have also often proven beneficial for the treatment of inflammatory and autoimmune diseases. In this review, we report on challenging examples that bridge between treatment of cancer and immune-mediated diseases, addressing mechanisms and experimental models as well as clinical investigations. Patient-derived tumor xenograft (PDX) (humanized) mouse models represent useful tools for preclinical evaluation of new therapies and biomarker identification. However, new developments using human ex vivo approaches modeling cancer, for example in microfluidic human organs-on-chips, promise to identify key molecular, cellular and immunological features of human cancer progression in a fully human setting. Classical drugs which bridge the gap, for instance, include cytotoxic drugs, proteasome inhibitors, PI3K/mTOR inhibitors and metabolic inhibitors. Biologicals developed for cancer therapy have also shown efficacy in the treatment of autoimmune diseases. In immune oncology, redirected chimeric antigen receptor (CAR) T cells have achieved spectacular remissions in refractory B cell leukemia and lymphoma and are currently under development for tolerance induction using cell-based therapies such as CAR Tregs or NK cells. Finally, a brief outline will be given of the lessons learned from bridging cancer and autoimmune diseases as well as tolerance induction.

Stromal Cells in the Pathogenesis of Inflammatory Bowel Disease

Up till now, research on inflammatory bowel disease [IBD] has mainly been focused on the immune cells present in the gastrointestinal tract. However, recent insights indicate that stromal cells also play an important and significant role in IBD pathogenesis. Stromal cells in the intestines regulate both intestinal epithelial and immune cell homeostasis. Different subsets of stromal cells have been found to play a role in other inflammatory diseases [e.g. rheumatoid arthritis], and these various stromal subsets now appear to carry out also specific functions in the inflamed gut in IBD. Novel potential therapies for IBD utilize, as well as target, these pathogenic stromal cells. Injection of mesenchymal stromal cells [MSCs] into fistula tracts of Crohn's disease patients is already approved and used in clinical settings. In this review we discuss the current knowledge of the role of stromal cells in IBD pathogenesis. We further outline recent attempts to modify the stromal compartment in IBD with agents that target or replace the pathogenic stroma.

Intraovarian injection of mesenchymal stem cells improves oocyte yield and in vitro embryo production in a bovine model of fertility loss

Valuable female cattle are continuously subject to follicular puncture (ovum pick-up - OPU). This technique is commonly used for in-vitro embryo production, but may result in ovarian lesion. Mesenchymal stem cells (MSC) ameliorate the function of injured tissues, but their use to treat ovarian lesions in cattle has not been established. We investigated whether a local injection of MSC would reduce the negative effects of repeated OPU under acute and chronic scenarios in bovines. First, we performed four OPU sessions and injected 2.5 × 106 MSCs immediately after the 4th OPU procedure (n = 5). The treated organs (right ovary) were compared to their saline-treated counterparts (left), and presented superior production of oocytes and embryos in the three following OPU sessions (P < 0.05). Then, cows with progressive fertility loss went through three OPU sessions. Animals received MSC, saline, or MSC + FSH in both ovaries after the first OPU. In the two following OPU sessions, the MSC and MSC + FSH - treated groups failed to present any significant alteration in the number of oocytes and embryos compared to saline-treated animals. Thus, MSC have beneficial effects on the fertility of OPU-lesioned cows, but not in cows with cystic ovarian disease and chronic ovarian lesions.

Inflammatory bowel disease position statement of the Italian Society of Colorectal Surgery (SICCR): Crohn's disease

The Italian Society of Colorectal Surgery (SICCR) promoted the project reported here, which consists of a position statement of Italian colorectal surgeons to address the surgical aspects of Crohn's disease management. Members of the society were invited to express their opinions on several items proposed by the writing committee, based on evidence available in the literature. The results are presented, focusing on relevant points. The present paper is not an alternative to available guidelines; rather, it offers a snapshot of the attitudes of SICCR surgeons about the surgical treatment of Crohn's disease. The committee was able to identify some points of major disagreement and suggested strategies to improve quality of available data and acceptance of guidelines.

Organoid-based regenerative medicine for inflammatory bowel disease

Inflammatory bowel disease (IBD) consists of two major idiopathic gastrointestinal diseases: ulcerative colitis and Crohn's disease. Although a significant advance has been achieved in the treatment of IBD, there remains a particular population of patients that are refractory to the conventional treatments, including the biologic agents. Studies have revealed the importance of "mucosal healing" in improving the prognosis of those difficult-to-treat patients, which indicates the proper and complete regeneration of the damaged intestinal tissue. In this regard, organoid-based regenerative medicine may have the potential to dramatically promote the achievement of mucosal healing in refractory IBD patients, and thereby improve their long-term prognosis as well. So far, studies have shown that hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) may have some beneficial effect on IBD patients through their transplantation or transfusion. Recent advance in stem cell biology has added intestinal stem cells (ISCs) as a new player in this field. It has been shown that ISCs can be grown in vitro as organoids and that those ex-vivo cultured organoids can be employed as donor cells for transplantation studies. Further studies using mice colitis models have shown that ex-vivo cultured organoids can engraft onto the colitic ulcers and reconstruct the crypt-villus structures. Such transplantation of organoids may not only facilitate the regeneration of the refractory ulcers that may persist in IBD patients but may also reduce the risk of developing colitis-associated cancers. Endoscopy-assisted transplantation of organoids may, therefore, become one of the alternative therapies for refractory IBD patients.

Stem and Progenitor Cells in the Pathogenesis and Treatment of Digestive Diseases

The global epidemic of chronic degenerative diseases expands rapidly. The pathogenesis of these noncommunicable disorders revolves around innate immunity, microbiome, and stem cell alterations. Understanding the mechanisms behind stem cell biology and their regulatory pathways is a key to understanding the origin of human disease. Stem cells are involved in tissue and organ damage and regeneration. The evidence is mounting that not only eukaryotic cells but also gut microbiota may release extracellular microvesicles that are absorbed from the gut into the portal and systemic circulation. Linking the fields of stem cells, innate immunity and microbiome research opens up new avenues to develop novel diagnostic (e.g., biomarkers), therapeutic (e.g., microbiome modulation, stem cell-based medicines), and prognostic (personalized diets) tools. In this chapter, we present the short overview of various stem and progenitor cells of adult tissues circulating in peripheral blood and their role in the pathogenesis and treatment of digestive diseases. We also briefly discuss the role of host-stem cell-microbial interactions as a new frontier of research in gastroenterology.

Refractory Complex Crohn's Perianal Fistulas: A Role for Autologous Microfragmented Adipose Tissue Injection

BACKGROUND

Complex perianal fistulas represent one of the most challenging manifestations of Crohn's disease. Combined surgical and medical therapy with biologic drugs today represent the first-line treatment option, but its efficacy does not exceed 60%. Recently, new therapeutic approaches, such as the use of mesenchymal stromal cells, have shown promising results. The adipose tissue is an abundant and easy to access source. The effectiveness, safety, and feasibility of local injections of microfragmented adipose tissue in patients with refractory complex fistulizing perianal Crohn's disease (PCD) were evaluated.

METHODS

Fifteen patients with persistent complex fistulizing PCD after biosurgical approach and subsequent surgical "rescue" repair were treated in S. Orsola-Malpighi Hospital with a single-local administration of microfragmented adipose tissue prepared using a minimal manipulation technique (Lipogems) in a closed system. Clinical outcomes were determined at 24-week follow-ups assessing success rate, defined as combined clinical and radiological remission.

RESULTS

Upon clinical examination at 24 weeks, 10 patients had combined remission (clinical and radiographic), 4 patients showed improvements, and 1 patient failed. The results were confirmed in all patients by pelvic MRI. No relevant postoperative complications nor adverse events were reported.

CONCLUSION

These results suggest that the local injection of autologous microfragmented adipose tissue is a safe and promising "rescue therapy" for patients with multiresistant complex fistulizing PCD. This approach might be proposed as routine because it is affordable, is minimally invasive, has no risk of sphincteric damage, and can be carried out in a day-surgery setting.

An Update on the Progress of Isolation, Culture, Storage, and Clinical Application of Human Bone Marrow Mesenchymal Stem/Stromal Cells

Bone marrow mesenchymal stem/stromal cells (BMSCs), which are known as multipotent cells, are widely used in the treatment of various diseases via their self-renewable, differentiation, and immunomodulatory properties. In-vitro and in-vivo studies have supported the understanding mechanisms, safety, and efficacy of BMSCs therapy in clinical applications. The number of clinical trials in phase I/II is accelerating; however, they are limited in the size of subjects, regulations, and standards for the preparation and transportation and administration of BMSCs, leading to inconsistency in the input and outcome of the therapy. Based on the International Society for Cellular Therapy guidelines, the characterization, isolation, cultivation, differentiation, and applications can be optimized and standardized, which are compliant with good manufacturing practice requirements to produce clinical-grade preparation of BMSCs. This review highlights and updates on the progress of production, as well as provides further challenges in the studies of BMSCs, for the approval of BMSCs widely in clinical application.

Long-term Evaluation of Allogeneic Bone Marrow-derived Mesenchymal Stromal Cell Therapy for Crohn's Disease Perianal Fistulas

BACKGROUND AND AIMS

The long-term safety and efficacy of allogeneic bone marrow-derived mesenchymal stromal cell [bmMSC] therapy in perianal Crohn's disease [CD] fistulas is unknown. We aimed to provide a 4-year clinical evaluation of allogeneic bmMSC treatment of perianal CD fistulas.

METHODS

A double-blind dose-finding study for local bmMSC therapy in 21 patients with refractory perianal fistulising Crohn's disease was performed at the Leiden University Medical Center in 2012-2014. All patients treated with bmMSCs [1 x 107 bmMSCs cohort 1, n = 5; 3 × 107 bmMSCs cohort 2, n = 5; 9 × 107 bmMSCs cohort 3, n = 5] were invited for a 4-year evaluation. Clinical events were registered, fistula closure was evaluated, and anti-human leukocyte antigen [HLA] antibodies were assessed. Patients were also asked to undergo a pelvic magnetic resonance imaging [MRI] and rectoscopy.

RESULTS

Thirteen out of 15 patients [87%] treated with bmMSCs were available for long-term follow-up. Two non-MSC related malignancies were observed. No serious adverse events thought to be related to bmMSC therapy were found. In cohort 2 [n = 4], all fistulas were closed 4 years after bmMSC therapy. In cohort 1 [n = 4] 63%, and in cohort 3 [n = 5] 43%, of the fistulas were closed, respectively. In none of the patients anti-HLA antibodies could be detected 24 weeks and 4 years after therapy. Pelvic MRI showed significantly smaller fistula tracts after 4 years.

CONCLUSIONS

Allogeneic bmMSC therapy for CD-associated perianal fistulas is also in the long-term a safe therapy. In bmMSC-treated patients, fistulas with closure at Week 24 were still closed after 4 years.

Mesenchymal stromal cell therapy in intestinal diseases

PURPOSE OF REVIEW

The advent of cell therapies, mainly based on the use of mesenchymal stromal cells (MSCs), represents a great step forward in the treatment of immune-mediated conditions. Here, we focus on those intestinal disorders wherein MSCs have been applied for immunotherapeutic purposes and whose results are available.

RECENT FINDINGS

By virtue of their ability to favour both tissue regeneration and immune tolerance, together with a substantial lack of immunogenicity, MSCs have gained huge attention in the last decade. Following abundant positive experimental data, a sizable number of clinical trials using MSCs as a new treatment in chronic inflammatory intestinal diseases were carried out with promising results and several are still ongoing. The main indication was refractory Crohn's disease wherein both feasibility and safety clearly emerged when treating the luminal phenotype with intravenous infusion/s, albeit no definitive conclusion on efficacy may be drawn. By contrast, the availability of robust demonstration also on the efficacy when treating the fistulizing phenotype through local injection/s of MSCs has led to approval of the marketing of an industrial preparation (darvadstrocel).

SUMMARY

Successful clinical implementation of this attractive option is hampered by a number of obstacles arising from methodology and regulation issues, which require the institution of interdisciplinary task forces before this cell therapy becomes a bedside reality.

The Immunomodulatory Functions of Mesenchymal Stromal/Stem Cells Mediated via Paracrine Activity

Mesenchymal stromal/stem cells (MSCs) exist in almost all tissues, possessing the potential to differentiate into specialized cell types and exert immunomodulatory functions. Thus, they have attracted much attention as a promising therapeutic candidate. Recent studies have demonstrated that paracrine signaling is mainly responsible for the involvement of MSCs in the modulation of immune responses and the progression of diseases. Through release of secretome consisting of a diverse range of cytokines, chemokines, and extracellular vesicles (EVs), MSCs convey regulatory messages to recipient immune cells in the microenvironment. In this review, we focus on the recent advances in how MSCs contribute to immunomodulation through the secretion of paracrine factors. The further improved understanding of the molecular mechanism underlying the interactions between MSCs and immune cells highlights the paracrine biology of MSCs in the modulation of the immune microenvironment and promotes the clinical application of MSCs in regenerative medicine and immune diseases.

Cx601 (darvadstrocel) for the treatment of perianal fistulizing Crohn's disease

Introduction: Given the well-documented difficulty to treat perianal fistulizing Crohn's disease (pCD), with 40% of patients experiencing recurrence even after reiterative surgery and advanced medical therapy, research in this field has focused on the role of mesenchymal stem cells (MSC). Areas covered: The aim of this article is to furnish an overview of the pathogenetic mechanisms, clinical applications and evidences for the use of MSC for pCD with particular focus on adipose-derived allogenic MSC including darvadstrocel. Expert Opinion: The effect of MSC on fistula healing is probably mediated by their anti-inflammatory properties more than by their ability to engraft and trans-differentiate in the healthy tissue. A holistic treatment of pCD, addressing different pathophysiological factors, may represent the key for an improvement in the healing rate. In this setting, MSC might play a role as 'augmentation' therapy in combination with more conventional treatments. Whether MSC have benefit in non-complex fistula in biological naïve patients, in complex fistula with many tracts and/or in rectovaginal fistulas, are unexplored fields that need further investigation. A central registry of pCD patients undergoing treatment with MSC should be created in order to elucidate the efficacy, safety and costs of stem cells treatment on long term follow up.

Controlling Gut Inflammation by Restoring Anti-Inflammatory Pathways in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is caused by a dysregulated immune response against normal components of the intestinal microflora combined with defective functioning of anti-inflammatory pathways. Currently, all therapies approved for IBD manipulate the immune system by inhibiting pro-inflammatory mechanisms, such as tumor necrosis factor-α, gut-homing α4β7 integrin, interleukin-12/interleukin-23, and Janus kinases. However, some IBD patients are non-responders to these drugs, which are also associated with serious side effects. Thus, it has been hypothesized that therapies aimed at restoring anti-inflammatory signals, by exploiting the tolerogenic potential of cytokines (interleukin-10, transforming growth factor-β, granulocyte macrophage colony-stimulating factor), immune cells (regulatory T cells, tolerogenic dendritic cells), or mesenchymal stem cells, might offer promising results in terms of clinical efficacy with fewer side effects. In this review, we provide new insights into putative novel treatments aimed at restoring anti-inflammatory signaling pathways in IBD.

Systematic review with meta-analysis: Safety and efficacy of local injections of mesenchymal stem cells in perianal fistulas

Perianal fistulas in Crohn's disease (CD) represent a highly debilitating and difficult‐to‐treat condition. Given emerging supportive evidence, we conducted a systematic review and meta‐analysis of all trials/observational studies to establish the safety and efficacy of local injections of mesenchymal stem cells (MSCs). The PRISMA‐P statement was applied for planning and reporting, and MEDLINE, EMBASE, Web of Science, Cochrane, CINAHL, ClinicalTrials.gov database, and ECCO 2017 proceedings were searched for published observational studies and one‐arm and randomized clinical trials (RCTs). Safety was assessed in terms of acute local/systemic events, long‐term events, and relatedness with MSC treatment. Efficacy was evaluated in terms of external and/or radiological closure of fistula tracks. After a review of 211 citations, 23 studies, including 696 participants, were evaluated. Four were RCTs with a total of 483 patients. Overall, fistula closure occurred in 80% of MSC‐treated patients. In RCTs, this rate was 64% in the MSC arm and 37% in the control arm (relative risk (RR) = 1.54). Radiological response occurred in 83% of MSC‐treated patients. Treatment‐related adverse events occurred in 1% of MSC‐treated patients, with severe treatment‐related adverse events reaching 0% over a median follow‐up of 6 months. In RCTs, treatment‐related adverse events occurred in 13% in the MSC arm and 24% in the control arm (RR = 0.65). The relapse rate was 0. These results suggest that a local MSC injection is safe and efficacious. Further clinical trials with standardized end‐points are required to ensure the timely implementation of this new therapy in the management of perianal CD.

Immunohematology Mesenchymal Stromal Cell-based Therapy: From Research to Clinic

Mesenchymal stromal cells (MSC) are nonhematopoietic cells that can be isolated from several adult and fetal tissues. MSC present specific features as the capacity to support hematopoiesis and to regulate immune response. Thus, the use of MSC as a cell therapeutic product in the field of immune-hematology is of great importance. In this review, we focused on human MSC and discussed their immune-hematologic properties and their translation toward therapeutic clinical applications. Thus, these features hold great promise for cell-based therapy and are of important relevance for the field.

Stem cells for luminal, fistulizing, and perianal inflammatory bowel disease: a comprehensive updated review of the literature

Much research has been performed over the last decade on stem cell therapy as treatment for patients with inflammatory bowel disease. Hematopoietic and mesenchymal stem cells, both allogeneic (from someone else) and autologous (from own patient), have been studied with safe and efficacious results in the majority of patients treated for luminal, perianal, and/or fistulizing disease. Here in this review, we highlight all human trials that have been conducted utilizing stem cell therapy treatment in patients with inflammatory bowel disease.

Pharmacological Approach to the Management of Crohn's Disease Patients with Perianal Disease

Perianal localization of Crohn's disease involves significant morbidity, affects quality of life and results in an increased use of healthcare resources. Medical and surgical therapies contribute to its management. The objective of this review is to address the current understanding in the management of perianal Crohn's disease, with the main focus in reviewing pharmacological therapies, including stem cells. In complex fistulas, once local sepsis has been controlled by surgical drainage and/or antibiotics, anti-TNF drugs (infliximab, adalimumab) are the first-line therapy, with or without associated immunomodulators. Combining surgery and anti-TNF therapy has additional benefits for healing. However, response is inadequate in up to half of cases. A possible role of new biological drugs in this context (vedolizumab, ustekinumab) is an area of ongoing investigation, as is the local application of autologous or allogeneic mesenchymal stem cells. These are non-hematopoietic multipotent cells with anti-inflammatory and immunomodulatory properties, the use of which may successfully treat refractory patients, and seem to be a promising and safe alternative to achieving fistula healing in Crohn's disease, without known systemic effects.

One more chance of fistula healing in inflammatory bowel disease: Stem cell therapy

Patients with fistulizing inflammatory bowel disease are traditionally difficult to treat. This patient population often experiences delayed or insufficient healing of fistulas using current standard regimens including antibiotics, immunomodulators, anti-tumor necrosis factor-αdrug, placement of setons, and surgical repair. Several studies over the last ten to fifteen years have been conducted using stem cell therapies with promising results in this patient population. These studies show stem cell therapy in fistulizing disease to be successful in healing between 60%-88% compared to currently 50% with infliximab. Moreover, remission was seen 24 wk to 52 wk in these studies. Further research with a multi-approach treatment using medications, stem cell therapy, and surgical interventions will likely be the future of this innovative treatment approach.

Mesenchymal stromal cells in the treatment of perianal fistulas in Crohn's disease

Significant unmet needs remain in patients with Crohn's disease and perianal fistulas. Mesenchymal stromal cells have potent immunomodulatory actions. The Phase II studies reported efficacy of local injection of mesenchymal stromal cells to achieve closure of fistulas. A Phase III trial demonstrated that in patients with Crohn's disease and refractory complex perianal fistulas, a single injection of 120 × 106 cells was superior to local injection of placebo associated with the same surgical procedure, in obtaining closure of the fistula tracts together with absence of abscesses >2 cm, 24 weeks after the injection, a stringent combined primary end point. The benefit over placebo was sustained 52 weeks after the single injection. The therapy is safe with adverse events limited to local pain.

Mesenchymal stem cells and immune disorders: from basic science to clinical transition

As a promising candidate seed cell type in regenerative medicine, mesenchymal stem cells (MSCs) have attracted considerable attention. The unique capacity of MSCs to exert a regulatory effect on immunity in an autologous/allergenic manner makes them an attractive therapeutic cell type for immune disorders. In this review, we discussed the current knowledge of and advances in MSCs, including its basic biological properties, i.e., multilineage differentiation, secretome, and immunomodulation. Specifically, on the basis of our previous work, we proposed three new concepts of MSCs, i.e., "subtotipotent stem cell" hypothesis, MSC system, and "Yin and Yang" balance of MSC regulation, which may bring new insights into our understanding of MSCs. Furthermore, we analyzed data from the Clinical Trials database ( http://clinicaltrials.gov ) on registered clinical trials using MSCs to treat a variety of immune diseases, such as graft-versus-host disease, systemic lupus erythematosus, and multiple sclerosis. In addition, we highlighted MSC clinical trials in China and discussed the challenges and future directions in the field of MSC clinical application.

Can a Conversation Between Mesenchymal Stromal Cells and Macrophages Solve the Crisis in the Inflamed Intestine?

Inflammatory bowel disease (IBD) is a group of chronic inflammatory conditions of the gastrointestinal tract characterized by an exacerbated mucosal immune response. Macrophages play pivotal roles in the maintenance of gut homeostasis but they are also implicated in the pathogenesis of IBD. They are highly plastic cells and their activation state depends on the local environment. In the healthy intestine, resident macrophages display an M2 phenotype characterized by inflammatory energy, while inflammatory M1 macrophages dominate in the inflamed intestinal mucosa. In this regard, modifying the balance of macrophage populations into an M2 phenotype has emerged as a new therapeutic approach in IBD. Multipotent mesenchymal stromal cells (MSCs) have been proposed as a promising cell-therapy for the treatment of IBD, considering their immunomodulatory and tissue regenerative potential. Numerous preclinical studies have shown that MSCs can induce immunomodulatory macrophages and have demonstrated that their therapeutic efficacy in experimental colitis is mediated by macrophages with an M2-like phenotype. However, some issues have not been clarified yet, including the importance of MSC homing to the inflamed colon and/or lymphoid organs, their optimal route of administration or whether they are effective as living or dead cells. In contrast, the mechanisms behind the effect of MSCs in human IBD are not known and more data are needed regarding the effect of MSCs on macrophage polarization that would support the observation reported in the experimental models. Nevertheless, MSCs have emerged as a novel method to treat IBD that has already been proven safe and with clinical benefits that could be administered in combination with the currently used pharmacological treatments.

Medical and surgical management of perianal Crohn's disease

Crohn's disease is increasingly thought to encompass multiple possible phenotypes. Perianal manifestations account for one such phenotype and represent an independent disease modifier. In its more severe form, perianal Crohn's disease confers a higher risk of a severe and disabling disease course, relapses, hospital admissions and operations. This, in turn, imposes a considerable burden and disability on patients. Identification of the precise manifestation is important, as management is nuanced, with both medical and surgical components, and is best undertaken in a multidisciplinary setting for both diagnosis and ongoing treatment. The introduction of biologic medication has heralded a significant addition to the management of fistulizing perianal Crohn's disease in particular, albeit with modest results. It remains a very challenging condition to treat and further work is required to optimize management in this group of patients.