Long-term results of adipose-derived stem cell therapy for the treatment of Crohn's fistula

Proceedings of the signature series event of the international society for cellular therapy: "Advancements in cellular therapies and regenerative medicine in digestive diseases," London, United Kingdom, May 3, 2017

A summary of the First Signature Series Event, "Advancements in Cellular Therapies and Regenerative Medicine for Digestive Diseases," held on May 3, 2017, in London, United Kingdom, is presented. Twelve speakers from three continents covered major topics in the areas of cellular therapy and regenerative medicine applied to liver and gastrointestinal medicine as well as to diabetes mellitus. Highlights from their presentations, together with an overview of the global impact of digestive diseases and a proposal for a shared online collection and data-monitoring platform tool, are included in this proceedings. Although growing evidence demonstrate the feasibility and safety of exploiting cell-based technologies for the treatment of digestive diseases, regulatory and methodological obstacles will need to be overcome before the successful implementation in the clinic of these novel attractive therapeutic strategies.

Uncultivated stromal vascular fraction is equivalent to adipose-derived stem and stromal cells on porous polyurethrane scaffolds forming adipose tissue in vivo

OBJECTIVES/HYPOTHESIS

To find an alternative approach to contemporary techniques in tissue augmentation and reconstruction, tissue engineering strategies aim to involve adipose-derived stem and stromal cells (ASCs) harboring a strong differentiation potential into various tissue types such as bone, cartilage, and fat.

STUDY DESIGN

Animal research.

METHODS

The stromal vascular fraction (SVF) was used directly as a cell source to provide a potential alternative to contemporary ASC-based adipose tissue engineering. Seeded in TissuCol fibrin, we applied ASCs or SVF cells to porous, degradable polyurethane (PU) scaffolds.

RESULTS

We successfully demonstrated the in vivo generation of volume-stable, well-vascularized PU-based constructs containing host-derived mature fat pads. Seeded human stem cells served as modulators of host-cell migration rather than differentiating themselves. We further demonstrated that preliminary culture of SVF cells was not necessary.

CONCLUSIONS

Our results bring adipose tissue engineering, together with automated processing devices, closer to clinical applicability. The time-consuming and cost-intensive culture and induction of the ASCs is not necessary.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:E206-E213, 2018.

Stem Cell Therapy in Refractory Perineal Crohn's Disease: Long-term Follow-up

AIM

To describe the long-term outcomes of adipose-mesenchymal stem cells, platelet-rich plasma, and endorectal advancement flaps in patients with Perineal Crohn's Disease.

METHOD

This was a single-center, prospective, observational pilot study performed between March 2013 and December 2016. The study included adult patients diagnosed with Perianal Crohn's Disease (with complex perianal fistulas) refractory to previous surgical and/or biological treatment. Patients underwent surgical treatment in two stages. Stage 1: Fistula mapping, drainage, seton placement and lipoaspiration to obtain adipose-mesenchymal stem cells were performed. Stage 2: The setons were removed, and the fistula tract was debrided. A small endorectal advancement flap was created, with closure of the previous internal fistula opening. Then, 100-120 million adipose-mesenchymal stem cells mixed with platelet-rich plasma were injected into the internal fistula opening and fistula tract.

RESULTS

The study included nine patients (seven females), with a median age of 36 years (r = 23-57). Eleven fistula tracks were treated, of which, two were pouch-vaginal fistulas. The median follow-up period was 31 months (r=21-37). At the end of the follow-up period, 10/11 (91%) fistulas were completely healed and 1/11 (9%) was partially healed. At the end of this period, there was no evidence of fistula relapse or adverse reactions in any patients. The Perianal Disease Activity Index and Inflammatory Bowel Disease Questionnaire scores significantly improved after the procedure.

CONCLUSION

Combined therapy with adipose-mesenchymal stem cells, platelet-rich plasma and endorectal advancement flaps yielded good results in patients with refractory Perineal Crohn's Disease. This article is protected by copyright. All rights reserved.

Comparison of Stromal Vascular Fraction with or Without a Novel Bioscaffold to Fibrin Glue in a Porcine Model of Mechanically Induced Anorectal Fistula

BACKGROUND

Anorectal fistulas (ARFs) are a common, devastating, event in the life of a patient with Crohn's disease. ARFs occur in up to 50% of patients with Crohn's disease. Treatment begins with surgical drainage of the initial abscess, followed by antibiotic therapy, then anti-inflammatory medications. If medical therapy fails to close the fistula tract, surgical intervention is often pursued. Surgery incurs risk of incontinence because of sphincter injury. Increasingly, the role of cell-based therapy is being investigated in ARFs. We evaluated the role a bioabsorbable scaffold plays in delivering cell-based therapy using a porcine model of AFR.

METHODS

ARFs were mechanically created and matured by setons. After 28 days, setons were removed; periaortic fat was harvested and processed for stromal vascular fraction (SVF). The cells were labeled with a membrane stain for later identification, then injected into the fistula or implanted through scaffold. Fistulas not treated with cells were injected with fibrin glue. Animals were monitored visually for healing at weeks 2 and 4, then euthanized to evaluate fistulas for histologic healing.

RESULTS

All fistulas (6/6) treated with SVF + scaffolds healed by week 2, compared with only 4/6 with just SVF and 0/5 treated with fibrin glue. Scaffolds retained SVF within the fistula tract more readily than injection method and SVF+scaffold treatment accelerated the healing process. Robust neovascularization was also seen in fistulas treated with SVF+scaffold. No adverse events occurred.

CONCLUSIONS

Scaffold technology may improve cell-based therapy healing rates for Crohn's ARFs. This advance should be investigated by human trials.

Systematic review of surgical interventions for Crohn's anal fistula

Background

Anal fistula occurs in approximately one in three patients with Crohn's disease and is typically managed through a multimodal approach. The optimal surgical therapy is not yet clear. The aim of this systematic review was to identify and assess the literature on surgical treatments of Crohn's anal fistula.

Methods

A systematic review was conducted that analysed studies relating to surgical treatment of Crohn's anal fistula published on MEDLINE, Embase and Cochrane databases between January 1995 and March 2016. Studies reporting specific outcomes of patients treated for Crohn's anal fistula were included. The primary outcome was fistula healing rate. Bias was assessed using the Cochrane ROBINS‐I and ROB tool as appropriate.

Results

A total of 1628 citations were reviewed. Sixty‐three studies comprising 1584 patients were ultimately selected in the analyses. There was extensive reporting on the use of setons, advancement flaps and fistula plugs. Randomized trials were available only for stem cells and fistula plugs. There was inconsistency in outcome measures across studies, and a high degree of bias was noted.

Conclusion

Data describing surgical intervention for Crohn's anal fistula are heterogeneous with a high degree of bias. There is a clear need for standardization of outcomes and description of study cohorts for better understanding of treatment options.

Cryopreserved Adipose Tissue-Derived Stromal/Stem Cells: Potential for Applications in Clinic and Therapy

Adipose-Derived Stromal/Stem Cells (ASC) have considerable potential for regenerative medicine due to their abilities to proliferate, differentiate into multiple cell lineages, high cell yield, relative ease of acquisition, and almost no ethical concerns since they are derived from adult tissue. Storage of ASC by cryopreservation has been well described that maintains high cell yield and viability, stable immunophenotype, and robust differentiation potential post-thaw. This ability is crucial for banking research and for clinical therapeutic purposes that avoid the morbidity related to repetitive liposuction tissue harvests. ASC secrete various biomolecules such as cytokines which are reported to have immunomodulatory properties and therapeutic potential to reverse symptoms of multiple degenerative diseases/disorders. Nevertheless, safety regarding the use of these cells clinically is still under investigation. This chapter focuses on the different aspects of cryopreserved ASC and the methods to evaluate their functionality for future clinical use.

Concise Review: A Safety Assessment of Adipose-Derived Cell Therapy in Clinical Trials: A Systematic Review of Reported Adverse Events

The popularity of adipose-derived cell therapy has increased over the last decade, and the number of studies published annually is growing. However, concerns regarding safety in the setting of previous malignancy or the use of allogeneic cells have been raised. We therefore aimed to systematically review all clinical studies using adipose-derived cell therapy to identify reported adverse events with a special focus on risk of thromboembolic, immunological, and oncological safety concerns. Our systematic search resulted in 70 included studies involving more than 1,400 patients that were treated with adipose-derived cell therapy. Safety assessment method was not described in 32 of the included studies. For studies involving systemic or cardiac administration, one case of pulmonary thromboembolism and cases of both myocardial and cerebral infarctions were described. In the setting of allogeneic cell therapy studies, where the production of specific antibodies toward donor cells was examined, it was noted that 19%-34% of patients develop antibodies, but the consequence of this is unknown. With regard to oncological safety, only one case of breast cancer recurrence was identified out of 121 patients. Adipose-derived cell therapy has so far shown a favorable safety profile, but safety assessment description has, in general, been of poor quality, and only adverse events that are looked for will be found. We encourage future studies to maintain a strong focus on the safety profile of cell therapy, so its safeness can be confirmed. Stem Cells Translational Medicine 2017;6:1786-1794.

Update on the mechanisms of homing of adipose tissue-derived stem cells

Adipose tissue-derived stem cells (ADSCs), which resemble bone marrow mesenchymal stromal cells (BMSCs), have shown great advantages and promise in the field of regenerative medicine. They can be readily harvested in large numbers with low donor-site morbidity. To date, a great number of preclinical and clinical studies have shown ADSCs' safety and efficacy in regenerative medicine. However, a better understanding of the mechanisms of homing of ADSCs is needed to advance the clinical utility of this therapy. In this review, the reports of the homing of ADSCs were searched using Pubmed and Google Scholar to update our knowledge. ADSCs were proved to interact with endothelial cells by expressing the similar integrins with BMSCs. In addition, ADSCs do not possess the dominant ligand for P-selectin, just like BMSCs. Stromal derived factor-1 (SDF-1)/CXCR4 and CXC ligand-5 (CXCL5)/CXCR2 interactions are the two main axes governing ADSCs extravasation from bone marrow vessels. Some more signaling pathways involved in migration of ADSCs have been investigated, including LPA/LPA1 signaling pathway, MAPK/Erk1/2 signaling pathway, RhoA/Rock signaling pathway and PDGF-BB/PDGFR-β signaling pathway. Status quo of a lack of intensive studies on the details of homing of ADSCs should be improved in the near future before clinical application.

Improvement of adipose tissue-derived cells by low-energy extracorporeal shock wave therapy

BACKGROUND

Cell-based therapies with autologous adipose tissue-derived cells have shown great potential in several clinical studies in the last decades. The majority of these studies have been using the stromal vascular fraction (SVF), a heterogeneous mixture of fibroblasts, lymphocytes, monocytes/macrophages, endothelial cells, endothelial progenitor cells, pericytes and adipose-derived stromal/stem cells (ASC) among others. Although possible clinical applications of autologous adipose tissue-derived cells are manifold, they are limited by insufficient uniformity in cell identity and regenerative potency.

METHODS

In our experimental set-up, low-energy extracorporeal shock wave therapy (ESWT) was performed on freshly obtained human adipose tissue and isolated adipose tissue SVF cells aiming to equalize and enhance stem cell properties and functionality.

RESULTS

After ESWT on adipose tissue we could achieve higher cellular adenosine triphosphate (ATP) levels compared with ESWT on the isolated SVF as well as the control. ESWT on adipose tissue resulted in a significantly higher expression of single mesenchymal and vascular marker compared with untreated control. Analysis of SVF protein secretome revealed a significant enhancement in insulin-like growth factor (IGF)-1 and placental growth factor (PLGF) after ESWT on adipose tissue.

DISCUSSION

Summarizing we could show that ESWT on adipose tissue enhanced the cellular ATP content and modified the expression of single mesenchymal and vascular marker, and thus potentially provides a more regenerative cell population. Because the effectiveness of autologous cell therapy is dependent on the therapeutic potency of the patient's cells, this technology might raise the number of patients eligible for autologous cell transplantation.

Clinical trials using mesenchymal stem cells in liver diseases and inflammatory bowel diseases

Mesenchymal stem cell (MSC) therapies have been used in clinical trials in various fields. These cells are easily expanded, show low immunogenicity, can be acquired from medical waste, and have multiple functions, suggesting their potential applications in a variety of diseases, including liver disease and inflammatory bowel disease. MSCs help prepare the microenvironment, in response to inflammatory cytokines, by producing immunoregulatory factors that modulate the progression of inflammation by affecting dendritic cells, B cells, T cells, and macrophages. MSCs also produce a large amount of cytokines, chemokines, and growth factors, including exosomes that stimulate angiogenesis, prevent apoptosis, block oxidation reactions, promote remodeling of the extracellular matrix, and induce differentiation of tissue stem cells. According to ClinicalTrials.gov, more than 680 clinical trials using MSCs are registered for cell therapy of many fields including liver diseases (more than 40 trials) and inflammatory bowel diseases (more than 20 trials). In this report, we introduce background and clinical studies of MSCs in liver disease and inflammatory bowel diseases.

Mesenchymal stem cells and their therapeutic applications in inflammatory bowel disease

Mesenchymal stem or stromal cells (MSCs) are non-hematopoietic stem cells that facilitate tissue regeneration through mechanisms involving self-renewal and differentiation, supporting angiogenesis and tissue cell survival, and limiting inflammation. MSCs were originally identified and expanded in long-term cultures of cells from bone marrow and other organs; and their native identity was recently confined into pericytes and adventitial cells in vascularized tissue. The multipotency, as well as the trophic and immunosuppressive effects, of MSCs have prompted the rapid development of clinical applications for many diseases involving tissue inflammation and immune disorders, including inflammatory bowel disease. Although standard criteria have been established to define MSCs, their therapeutic efficacy has varied significantly among studies due to their natural heterogenicity. Thus, understanding the biological and immunological features of MSCs is critical to standardize and optimize MSCs-based therapy. In this review, we highlight the cellular and molecular mechanisms involved in MSCs-mediated tissue repair and immunosuppression. We also provide an update on the current development of MSCs-based clinical trials, with a detailed discussion of MSC-based cell therapy in inflammatory bowel disease.

Systematic review with meta-analysis: the efficacy and safety of stem cell therapy for Crohn's disease

Background and aims

Stem cell therapy (SCT) for the treatment of Crohn’s disease (CD) is still in its infancy, and whether SCT is associated with improved outcomes is unclear. We performed a meta-analysis to evaluate the efficacy and safety of patients receiving SCT.

Methods

Electronic databases were searched for studies that reported the use of stem cells for the treatment of patients with CD. Raw data from included studies were pooled for effect estimates. Subgroup analyses were performed for exploration of heterogeneity regarding all outcomes.

Results

We analyzed 21 studies comprising 514 patients with active CD. A random-effects meta-analysis of studies of SCT as systemic infusion showed 56% (95% confidence interval (CI) 33–76, n = 150) of patients achieved clinical response. Similarly, random-effects pooled rates of clinical or endoscopic remission were 46% (95% CI 25–69, n = 116) and 15% (95% CI 0–50, n = 48), respectively. A random-effects meta-analysis of all perianal CD studies showed that 57% (95% CI 44–69%, n = 251) of patients had healed fistula with SCT, with an odds ratio of 3.83 (95% CI 1.06–13.86, n = 121, P = 0.04) versus control. The pooled rate of clinical recurrence was high at 16% (95% CI 4–34, n = 101) with follow-up >12 months. The pooled rates of severe adverse events (SAEs) and SAEs related to SCT were 12% (95% CI 6–23, n = 378) and 8% (95% CI 3–18, n = 378), respectively. The Egger test suggests no publication bias existed for fistula healing (P = 0.36), but did for clinical response (P = 0.003).

Conclusions

SCT seems potentially effective and may serve as an alternative treatment for refractory active CD. Toxicity will remain the most significant barrier to systemic SCT in patients with CD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0570-x) contains supplementary material, which is available to authorized users.

Autologous adipose tissue-derived stem cells for the treatment of complex perianal fistulas not associated with Crohn's disease: a phase II clinical trial for safety and efficacy

PURPOSE

Injection of adipose tissue-derived stem cells (ASCs) is a novel method for the treatment of complex perianal fistulas. We aimed to evaluate the safety and efficacy of ASCs in the treatment of complex anal fistulas not associated with Crohn's disease.

METHODS

A phase II clinical trial was performed comparing two different doses of ASCs (group 1: 1 × 10⁷ cells/mL and group 2: 2 × 10⁷ cells/mL). Eligible patients were administered an amount of ASCs proportional to the length of the fistula by injection into the submucosal layer surrounding the internal opening and inside of the fistula tract. ASCs at twice the initial concentration were administered if complete closure was not achieved within 8 weeks. The efficacy endpoint was the complete closure of fistulas 8 weeks after injection. Patients demonstrating complete closure at week 8 were subjected to follow-up for 6 months.

RESULTS

Fifteen patients were injected with ASCs; thirteen completed the study. Complete closure was observed in 69.2% (9/13) of patients at 8 weeks. Three of five patients in group 1, and six of eight in group 2 displayed complete closure; no significant differences were observed between the groups. Six of nine patients who showed complete closure participated in additional follow-up; five (83.3%) showed persistent response at 6 months. No grade 3 or 4 adverse events (AEs) were observed; observed AEs were not related to ASC treatment.

CONCLUSION

ASCs might be a good option for the treatment of complex perianal fistulas are not healed by conventional operative procedures.

Local application of adipose-derived mesenchymal stem cells supports the healing of fistula: prospective randomised study on rat model of fistulising Crohn's disease

OBJECTIVE

Local application of adipose-derived mesenchymal stem cells (ADSC) represents a novel approach for the management of perianal fistula in patients with Crohn's disease. A randomised study on an animal model was performed to investigate the efficacy and to detect the distribution of implanted ADSCs by bioluminescence (BLI).

MATERIALS AND METHODS

A caecostomy was used as a fistula model in 32 Lewis rats. The ADSCs were isolated from transgenic donor expressing firefly luciferase. Animals were randomly assigned to groups given injections of 4 × 10⁶ cells (n = 16, group A) or placebo (n = 16, group B) in the perifistular tissue. Fistula drainage assessment was used to evaluate the fistula healing. After application of D-luciferin, cell viability and distribution was detected using an IVIS Lumina XR camera on days 0, 2, 7, 14 and 30.

RESULTS

The fistula was identified as healed in 6 (38%) animals in group A vs. 1 case (6.3%) in group B (p = .033). The BLI was strongest immediately after administration of ADSCs 31.2 × 10⁴ (6.09-111 × 10⁴) p/s/cm²/sr. The fastest decrease was observed within the first 2 days when values fell by 50.2%. The BLI 30 days after injection was significantly higher in animals with healed fistulas - 8.23 × 10⁴ (1.18-16.9 × 10⁴) vs. 1.74 × 10⁴ (0.156-6.88 × 10⁴); p = .0393.

CONCLUSIONS

Local application of ADSCs resulted in significantly higher fistula closure rate on an animal model. BLI monitoring was proved to be feasible and showed rapid reduction of the ADSC mass after application. More viable cells were detected in animals with healed fistula at the end of the follow-up.

Efficacy of Mesenchymal Stromal Cells for Fistula Treatment of Crohn's Disease: A Systematic Review and Meta-Analysis

BACKGROUND AND AIM

The introduction of mesenchymal stromal cells (MSCs) has changed the management of Crohn's fistula, while it remains controversial. The aim of this study was to provide an overview of efficacy and optimum state of MSCs treatment on Crohn's fistula.

METHODS

Studies reporting MSCs treatment on Crohn's fistula were searched and included. A fixed-effects model was used to assess the efficacy of MSCs, and outcomes of healing and recurrence were used to evaluate the best states of MSCs intervention.

RESULTS

Fourteen articles were enrolled (n = 477). Pooled analysis showed MSCs had a significant efficacy compared to other treatments [risk difference: 0.21 (0.09, 0.32), P = 0.000]. Notably, after MSCs treatment, the group of Crohn's disease activity index (CDAI) baseline >150 group had a higher healing rate (HR) and a clinical response (a change in CDAI of >50 points) (79.17 ± 8.78 vs. 47.54 ± 15.90, P = 0.011) compared to CDAI baseline of <150. The duration time of CD and fistulas had a negative correlation with HR accompanied by MSC therapy (r = -0.900, -0.925). Then, a moderate dose MSCs (2-4 × 10⁷ cells/ml) had a higher HR (80.07%) and lower recurrence rate (RR 13.98%) compared to other dosages. Moreover, adipose-derived MSCs therapy had an advantage over bone marrow-derived MSCs in terms of low RR (7.4 ± 4.28 vs. 13.39 ± 0.89).

CONCLUSIONS

The evidence supported the effect of MSCs at a more appropriate time of Crohn's fistula. And CDAI baseline (the points >150) has been a candidate for evaluating effectiveness of MSCs application on Crohn's fistula.

Perianal Crohn's disease: challenges and solutions

Perianal Crohn’s disease affects a significant number of patients with Crohn’s disease and is associated with poor quality of life. The nature of the disease, compounded by presentation of various disease severities, has made the treatment of perianal Crohn’s disease difficult. The field continues to evolve with the use of both historical and contemporary solutions to address the challenges associated with it. The goal of this article is to review current literature regarding medical and surgical treatment, as well as the future directions of therapy.

Is Stem Cell Therapy Ready for Prime Time in Treatment of Inflammatory Bowel Diseases?

Autologous hematopoietic stem cell transplantation (HSCT) and mesenchymal stromal cell therapy have been proposed for patients with refractory Crohn's disease (CD) and fistulizing CD, respectively. Will these highly advanced techniques be available only for select patients, at specialized centers, or is further clinical development justified, with the aim of offering widespread, more definitive therapeutic options for often very difficult to treat disease? Patients with CD who are eligible for HSCT have typically been failed by most approved therapies, have undergone multiple surgeries, and have coped with years of disease activity and poor quality of life. The objective of HSCT is to immediately shut down the immune response and allow the transplanted stem cells to develop into self-tolerant lymphocytes. For patients with fistulizing CD, mesenchymal stromal cell therapy deposits MSCs locally, into fistulizing tracts, to down-regulate the local immune response and induce wound healing. Recent trials have produced promising results for HSCT and mesenchymal stromal cell therapy as alternatives to systemic therapies and antibiotics for patients with inflammatory bowel diseases, but are these immunotherapies ready for prime time?

Characteristics, applications and prospects of mesenchymal stem cells in cell therapy

Recent advances in the field of cell therapy and regenerative medicine describe mesenchymal stem cells (MSCs) as potential biological products due to their ability to self-renew and differentiate. MSCs are multipotent adult cells with immunomodulatory and regenerative properties, and, given their therapeutic potential, they are being widely studied in order to evaluate their viability, safety and efficacy. In this review, we describe the main characteristics and cellular sources of MSCs, in addition to providing an overview of their properties and current clinical applications, as well offering updated information on the regulatory aspects that define them as somatic cell therapy products. Cell therapy based on MSCs is offered nowadays as a pharmacological alternative, although there are still challenges to be addressed in this regard.

Comparison of Adipose-Derived and Bone Marrow Mesenchymal Stromal Cells in a Murine Model of Crohn's Disease

BACKGROUND

Mesenchymal stromal cells (MSCs) have been used in the treatment of Crohn's disease (CD) because of the immunomodulatory ability.

AIM

The aim of this study was to investigate the therapeutic effect of adipose-derived MSCs (AD-MSCs) and to compare the therapeutic effect of AD-MSCs with that of bone marrow MSCs (BM-MSCs) in a murine model of CD.

METHODS

Murine colitis model of CD was created by trinitrobenzene sulfonic acid (TNBS). Twelve hours after treatment with TNBS, the mouse model was injected with MSCs intraperitoneally. Real-time polymerase chain reaction and immunohistochemistry staining were used to measure the expression levels of inflammatory cytokines in colonic tissues to investigate the therapeutic effect of AD-MSCs. The ten-day survival was recorded after infusion of MSCs.

RESULTS

Intraperitoneal injection of MSCs alleviated the clinical and histopathologic severity of intestinal inflammation, and improved the survival of the TNBS-induced mouse model of CD. AD-MSCs could effectively increase the expression of interleukin-10 and reduce the secretion of pro-inflammatory cytokines including tumor necrosis factor-α, interleukin-12, and vascular endothelial growth factor. The mucosal injury was repaired by AD-MSCs. These effects were comparable between AD-MSCs and BM-MSCs.

CONCLUSIONS

The therapeutic effect appears similar between AD-MSCs and BM-MSCs in treating CD. AD-MSCs may be a potential alternative of cell-based therapy for CD.

Mesenchymal stem/stromal cell therapy for inflammatory bowel disease: an updated review with maintenance of remission

PURPOSE OF REVIEW

There is a need for novel therapies for inflammatory bowel diseases (IBDs) that are well tolerated and effective. Currently, mesenchymal stem/stromal cells (MSCs) are being investigated in clinical trials for treatment of IBD. In this review, we update the recently published studies with an emphasis on the long-term efficacy of MSC therapy for IBD.

RECENT FINDINGS

A cumulative body of data, including a recent phase III randomized controlled trial demonstrated excellent fistula healing in patients with refractory Crohn's perianal fistulae treated via local injections of MSCs and with a good safety profile. Follow-up studies suggest long-term efficacy of MSC therapy for complex perianal Crohn's disease fistulae; however, the efficacy decreases over time and may necessitate repeat treatment. Systemic (intravenous) therapy for luminal IBD offers a relatively well tolerated alternative but its efficacy remains unclear.

SUMMARY

Recent studies demonstrate that MSCs are well tolerated and have an excellent short-term efficacy for the management of refractory fistulizing perianal Crohn's disease. The current data suggest that its influence may 'wear off' over time. More data on larger number of patients with longer duration of follow-up in the setting of a randomized placebo controlled trial are needed to confirm these promising results. For luminal IBD, there is a need for more mechanistic studies in representative preclinical murine models, and the results of an ongoing phase III randomized controlled trial are eagerly awaited.

Adeno-Associated Virus 5 Transduces Adipose-Derived Stem Cells with Greater Efficacy Than Other Adeno-Associated Viral Serotypes

Adipose-derived stem cells (ASCs) have shown potential in the treatment of a myriad of diseases; however, infusion of cells alone is unlikely to provide the full range of potential therapeutic applications. Transient genetic manipulation of ASCs could increase their repair and regeneration characteristics in a disease-specific context, essentially transforming them into drug-eluting depots. The goal of this study was to determine the optimal parameters necessary to transduce ASCs with recombinant adeno-associated virus (rAAV), an approved gene therapy vector that has never been associated with disease. Transduction and duration of gene expression of the most common recombinant AAV vectors were tested in this study. Among all tested serotypes, rAAV5 resulted in both the highest and longest term expression. Furthermore, we determined the glycosylation profile of ASCs before and after neuraminidase treatment and demonstrate that rAAV5 transduction requires plasma membrane-associated sialic acid. Future studies will focus on the optimization of gene delivery to ASCs, using rAAV5 as the vector of choice, to drive biological drug delivery, engraftment, and disease correction.

Mesenchymal stromal cell-based therapy: Regulatory and translational aspects in gastroenterology

The past decade has witnessed an outstanding scientific production focused towards the possible clinical applications of mesenchymal stromal cells (MSCs) in autoimmune and chronic inflammatory diseases. This raised the need of novel standards to adequately address quality, efficacy and safety issues of this advanced therapy. The development of a streamlined regulation is currently hampered by the complexity of analyzing dynamic biological entities rather than chemicals. Although numerous pieces of evidence show efficacy in reducing intestinal inflammation, some inconsistencies between the mechanisms of action of rodent vs human MSCs suggest caution before assigning translational value to preclinical studies. Preliminary evidence from clinical trials showed efficacy of MSCs in the treatment of fistulizing Crohn’s disease (CD), and preparations of heterologous MSCs for CD treatment are currently tested in ongoing clinical trials. However, safety issues, especially in long-term treatment, still require solid clinical data. In this regard, standardized guidelines for appropriate dosing and methods of infusion could enhance the likelihood to predict more accurately the number of responders and the duration of remission periods. In addition, elucidating MSC mechanisms of action could lead to novel and more reliable formulations such as those derived from the MSCs themselves (e.g., supernatants).

Concise Review: The Use of Adipose-Derived Stromal Vascular Fraction Cells and Platelet Rich Plasma in Regenerative Plastic Surgery

Tissue engineering has emerged at the intersection of numerous disciplines to meet a global clinical need for technologies to promote the regeneration of tissues. Recently, many authors have focused their attention on mesenchymal stem/stromal cells (MSCs) for their capacity to differentiate into many cell lineages. The most widely studied cell types are bone marrow mesenchymal stem cells and adipose-derived stem cells (ASCs), which display similar results. Biomaterials, cells, and growth factors are needed to design a regenerative plastic surgery approach in the treatment of organ and tissue defects, but not all tissues are created equal. The aim of this article is to describe the advances in tissue engineering through the use of ASCs, platelet rich plasma, and biomaterials to enable regeneration of damaged complex tissue. Stem Cells 2017;35:117-134.

Concise Review: Stem Cell Trials Using Companion Animal Disease Models

Studies to evaluate the therapeutic potential of stem cells in humans would benefit from more realistic animal models. In veterinary medicine, companion animals naturally develop many diseases that resemble human conditions, therefore, representing a novel source of preclinical models. To understand how companion animal disease models are being studied for this purpose, we reviewed the literature between 2008 and 2015 for reports on stem cell therapies in dogs and cats, excluding laboratory animals, induced disease models, cancer, and case reports. Disease models included osteoarthritis, intervertebral disc degeneration, dilated cardiomyopathy, inflammatory bowel diseases, Crohn's fistulas, meningoencephalomyelitis (multiple sclerosis-like), keratoconjunctivitis sicca (Sjogren's syndrome-like), atopic dermatitis, and chronic (end-stage) kidney disease. Stem cells evaluated in these studies included mesenchymal stem-stromal cells (MSC, 17/19 trials), olfactory ensheathing cells (OEC, 1 trial), or neural lineage cells derived from bone marrow MSC (1 trial), and 16/19 studies were performed in dogs. The MSC studies (13/17) used adipose tissue-derived MSC from either allogeneic (8/13) or autologous (5/13) sources. The majority of studies were open label, uncontrolled studies. Endpoints and protocols were feasible, and the stem cell therapies were reportedly safe and elicited beneficial patient responses in all but two of the trials. In conclusion, companion animals with naturally occurring diseases analogous to human conditions can be recruited into clinical trials and provide realistic insight into feasibility, safety, and biologic activity of novel stem cell therapies. However, improvements in the rigor of manufacturing, study design, and regulatory compliance will be needed to better utilize these models. Stem Cells 2016;34:1709-1729.

Investigating cell therapy for inflammatory bowel disease

INTRODUCTION

Advances in immuno-modulatory therapies, including anti-TNF-α therapies, have greatly increased the chance to achieve long-term remission of inflammatory bowel disease (IBD) patients. However, as the importance of mucosal healing has been demonstrated in a number of clinical studies, new cell-based therapies that can regenerate and fully restore the intestinal mucosal functions are currently under development.

AREA COVERED

In this review, we feature the recent challenges of cell-based therapies that are applied to the treatment of IBD. In particular, we will focus on hematopoietic stem cells (HSC), mesenchymal stem cells (MSCs) and intestinal stem cells (ISCs) as the candidate source for cell-based therapy targeted to treat IBD. The current status, as well as the expected advantages and disadvantages of those transplantations will be summarized and discussed.

EXPERT OPINION

Transplantation of HSC, MSC and ISC may have different levels of potential in their ability to exert an immunomodulatory or pro-regenerative effect. Combined cell therapies, such as co-transplantation of MSC and ISC, may provide improved therapeutic outcome compared to transplantation of a single cell population. Those cell-based therapies may not only improve the disease activity or tissue regeneration, but may also have the potential to decrease the risk of developing colitis-associated cancers.

Concise Review: Cellular Therapies: The Potential to Regenerate and Restore Tolerance in Immune-Mediated Intestinal Diseases

Chronic inflammatory enteropathies, including celiac disease, Crohn's disease, and ulcerative colitis, are lifelong disabling conditions whose cure is still an unmet need, despite the great strides made in understanding their complex pathogenesis. The advent of cellular therapies, mainly based on the use of stem cells, represents a great step forward thanks to their multitarget strategy. Both hematopoietic stem cells (HSC) and mesenchymal stem/stromal cells (MSC) have been employed in the treatment of refractory cases with promising results. The lack of immunogenicity makes MSC more suitable for therapeutic purposes as their infusion may be performed across histocompatibility locus antigen barriers without risk of rejection. The best outcome has been obtained when treating fistulizing Crohn's disease with local injections of MSC. In addition, both HSC and MSC proved successful in promoting regeneration of intestinal mucosa, and favoring the expansion of a T-cell regulatory subset. By virtue of the ability to favor mucosal homeostasis, this last cell population has been exploited in clinical trials, with inconsistent results. Finally, the recent identification of the epithelial stem cell marker has opened up the possibility of tissue engineering, with an array of potential applications for intestinal diseases. However, the underlying mechanisms of action of these interconnected therapeutic strategies are still poorly understood. It is conceivable that over the next few years their role will become clearer as the biological interactions with injured tissues and the hierarchy by which they deliver their action are unraveled through a continuous moving from bench to bedside and vice versa. Stem Cells 2016;34:1474-1486.

Treatment of perianal fistulas with human embryonic stem cell-derived mesenchymal stem cells: a canine model of human fistulizing Crohn's disease

Aim: To evaluate the safety and efficacy of intralesional injection of human embryonic stem cell (hESC)-derived mesenchymal stem/stromal cells (MSCs) in canine anal furunculosis dogs. Materials & methods: Dogs naturally develop an immune-mediated disease called canine anal furunculosis, which shares many features with human fistulizing Crohn's disease. Results: The hESC-MSCs were well tolerated and 1 month postinjection, accompanied by reduced serum levels of IL-2 and IL-6, two inflammatory cytokines associated with Crohn's disease. All six dogs were found to be completely free of fistulas at 3 months postinjection. However, at 6 months, two dogs had some fistula relapse. Conclusion: Results of this study provide the first evidence of the safety and therapeutic potential of hESC-MSCs in a large animal model.

Mesenchymal Stem Cell Therapy for Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

Recent advances in inflammatory bowel disease (IBD) therapeutics include novel medical, surgical, and endoscopic treatments. Among these, stem cell therapy is still in its infancy, although multiple studies suggest that the immunomodulatory effect of stem cell therapy may reduce inflammation and tissue injury in patients with IBD. This review discusses the novel avenue of stem cell therapy and its potential role in the management of ulcerative colitis and Crohn's disease. We conducted a comprehensive literature search to identify studies examining the role of stem cell therapy (without conditioning and immunomodulatory regimens) in IBD. Taken together, these studies suggest a promising role for stem cell therapy in IBD although the substantial challenges, such as cost and inadequate/incomplete characterization of effect, limit their current use in clinical practice.

Enzymatic and non-enzymatic isolation systems for adipose tissue-derived cells: current state of the art

In the past decade, adipose tissue became a highly interesting source of adult stem cells for plastic surgery and regenerative medicine. The isolated stromal vascular fraction (SVF) is a heterogeneous cell population including the adipose-derived stromal/stem cells (ASC), which showed regenerative potential in several clinical studies and trials. SVF should be provided in a safe and reproducible manner in accordance with current good manufacturing practices (cGMP). To ensure highest possible safety for patients, a precisely defined procedure with a high-quality control is required. Hence, an increasing number of adipose tissue-derived cell isolation systems have been developed. These systems aim for a closed, sterile, and safe isolation process limiting donor variations, risk for contaminations, and unpredictability of the cell material. To isolate SVF from adipose tissue, enzymes such as collagenase are used. Alternatively, in order to avoid enzymes, isolation systems using physical forces are available. Here, we provide an overview of known existing enzymatic and non-enzymatic adipose tissue-derived cell isolation systems, which are patented, published, or already on the market.