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

Longitudinal evaluation of the cutaneous and rectal microbiota of German shepherd dogs with perianal fistulas undergoing therapy with ciclosporin and ketoconazole

BACKGROUND

Perianal fistulas are painful ulcers or sinus tracts that disproportionately affect German shepherd dogs and are proposed as a spontaneous animal model of fistulising Crohn's disease.

OBJECTIVES

To characterise the rectal and cutaneous microbiota in German shepherd dogs with perianal fistulas and to investigate longitudinal shifts with lesion resolution during immunomodulatory therapy.

ANIMALS

Eleven German shepherd dogs with perianal fistulas and 15 healthy German shepherd dogs.

MATERIALS AND METHODS

Affected dogs were evaluated and swabbed at three visits, 30 days apart, while undergoing treatment with ciclosporin and ketoconazole. Healthy German shepherd dogs were contemporaneously sampled. Sites included the rectum, perianal skin and axilla. The microbiome was evaluated following sequencing of the V4 hypervariable region of the 16S ribosomal RNA (rRNA) gene.

RESULTS

Alpha diversity was not significantly different between healthy and affected dogs at each of the three body sites (p > 0.5), yet rectal and perianal beta diversities from affected dogs differed significantly from those of healthy dogs at Day 0 (p = 0.004). Rectal and perianal relative abundance of Prevotella spp. increased and perianal Staphylococcus spp. relative abundance decreased in affected dogs over time, coincident with lesion resolution.

CONCLUSIONS AND CLINICAL RELEVANCE

Changes in lesional cutaneous and rectal microbiota occur in German shepherd dogs with perianal fistulas and shift over time with lesion resolution during immunomodulatory therapy. Further investigations of the role of cutaneous and enteric microbiota in the pathogenesis of perianal fistulas, and whether manipulation of microbial populations may ameliorate disease, are needed.

hUC-MSCs therapy for Crohn's disease: efficacy in TNBS-induced colitis in rats and pilot clinical study

BACKGROUND

The use of mesenchymal stem cells (MSCs) has recently emerged as a promising new therapeutic strategy for many diseases including perianal fistulizing Crohn's disease (CD). Whether hUC-MSCs can promote the healing of luminal ulcer in CD has not been studied so far.

METHODS

The model of TNBS-induced colitis in rats was used to confirm the efficacy of hUC-MSCs in the treatment of CD. Then, seventeen CD patients refractory to or unsuitable for currently available therapies were enrolled and received once submucosal local injection through colonoscopy combined with once intravenous drip on the next day. All patients received a 24-week follow-up. Clinical and laboratory assessments were monitored at baseline, week 4, 8, 12, and 24. Endoscopic evaluations were conducted at baseline and week 12. Mucosal specimens were obtained at the margin of lesions by endoscopy biopsies and used for RNA sequencing. Two hUC-MSCs co-culture systems were established in vitro, one with the mucosa specimens and the other with M1 macrophages induced from THP1. The expressions of genes representing inflammation (TNFα, IL-6, and IL-1β) and intestinal barrier function (ZO1, CLAUDIN1, and CDH1) were tested by RT-PCR.

FINDINGS

hUC-MSCs treatment increased body weight and decreased disease activity index (DAI), colon macroscopic damage index (CMDI), and histopathological score (HPS) of rats with TNBS-induced colitis. The results of the clinical study also showed that this mode of hUC-MSCs application was associated with regression of intestinal ulceration. Eight patients (47%) got endoscopic responses (SES-CD improvement of ≥50% from baseline) and three patients (17.65%) got mucosal healing (SES-CD is zero), with a parallel improvement of clinical and laboratory parameters without serious adverse events. RNA sequencing showed hUC-MSCs therapy was associated with an upregulation of transcripts linked to intestinal epithelial barrier integrity and a downregulation of inflammatory signaling pathways in the intestinal mucosa, especially the TNF signaling pathway, IL-17 signaling pathway, and TLR signaling pathway. RNA expression of intestinal epithelial tight junction protein (ZO1, CLAUDIN1, and CDH1), and the RNA expression of major intestinal inflammatory factors in CD (IL-1β, IL-6, and TNFα, p < 0.001 for all) were improved significantly. Moreover, hUC-MSCs could attenuate the polarization of M1 macrophage induced from THP1, thereby decreasing the mRNA expression of IL-1β, IL-6, and TNFα significantly (p < 0.05 for all). TSG-6 expression was evaluated in hUC-MSCs culture supernatant after treatment with TNFα, IFNγ, and LPS for 48 h. And hUC-MSCs could inhibit the phosphorylation of JAK/STAT1 in the intestinal mucosa of CD patients.

INTERPRETATION

hUC-MSCs transplantation alleviated TNBS-induced colitis in rats. In this pilot clinical study, preliminary data suggested that this approach to administering hUC-MSCs might have potential for clinical efficacy and manageable safety in treating refractory CD, potentially providing hope for better outcomes. No serious adverse events were observed.

FUNDING

This work was funded by General Program of National Natural Science Foundation of China (Grant No. 82270639), the Scientific research project of Shanghai Municipal Health Committee (Grant No. 202240001), Specialty Feature Construction Project of Shanghai Pudong New Area Health Commission (Grant No. PWZzb2022-05), Shanghai East Hospital Youth Research and Cultivation Foundation program (Grant No. DFPY2022015), Peak Disciplines (Type IV) of Institutions of Higher Learning in Shanghai and Technology Development Project of Pudong Science, Technology and Economic Commission of Shanghai (Grant No. PKJ2021-Y08).

Immortalized Canine Adipose-Derived Mesenchymal Stem Cells Maintain the Immunomodulatory Capacity of the Original Primary Cells

Mesenchymal stem cells (MSCs) are a promising cell source for stem cell therapy of intractable diseases in veterinary medicine, but donor-dependent cellular heterogeneity is an issue that influences therapeutic efficacy. Thus, we previously established immortalized cells that maintain the fundamental properties of primary cells, but functional evaluation had not been performed. Therefore, we evaluated the immunomodulatory capacity of the immortalized canine adipose-derived MSCs (cADSCs) in vitro and in vivo to investigate whether they maintain primary cell functions. C57BL/6J mice were treated with dextran sulfate sodium (DSS) to induce colitis, injected intraperitoneally with immortalized or primary cADSCs on day 2 of DSS treatment, and observed for 10 days. Administration of immortalized cADSCs improved body weight loss and the disease activity index (DAI) in DSS-induced colitic mice by shifting peritoneal macrophage polarity from the M1 to M2 phenotype, suppressing T helper (Th) 1/Th17 cell responses and inducing regulatory T (Treg) cells. They also inhibited the proliferation of mouse and canine T cells in vitro. These immunomodulatory effects were comparable with primary cells. These results highlight the feasibility of our immortalized cADSCs as a cell source for stem cell therapy with stable therapeutic efficacy because they maintain the immunomodulatory capacity of primary cells.

Successful treatment of perianal fistulas in two dogs with oclacitinib

Perianal fistula (PAF) formation in dogs is a frustrating and painful disease, occurring primarily in German shepherd dogs. Ciclosporin has become the recommended treatment of choice yet may be associated with numerous adverse effects. This case report describes the successful treatment of two cases of PAF with oclacitinib.

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.

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

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

MSCs vs. iPSCs: Potential in therapeutic applications

Over the past 2 decades, mesenchymal stem cells (MSCs) have attracted a lot of interest as a unique therapeutic approach for a variety of diseases. MSCs are capable of self-renewal and multilineage differentiation capacity, immunomodulatory, and anti-inflammatory properties allowing it to play a role in regenerative medicine. Furthermore, MSCs are low in tumorigenicity and immune privileged, which permits the use of allogeneic MSCs for therapies that eliminate the need to collect MSCs directly from patients. Induced pluripotent stem cells (iPSCs) can be generated from adult cells through gene reprogramming with ectopic expression of specific pluripotency factors. Advancement in iPS technology avoids the destruction of embryos to make pluripotent cells, making it free of ethical concerns. iPSCs can self-renew and develop into a plethora of specialized cells making it a useful resource for regenerative medicine as they may be created from any human source. MSCs have also been used to treat individuals infected with the SARS-CoV-2 virus. MSCs have undergone more clinical trials than iPSCs due to high tumorigenicity, which can trigger oncogenic transformation. In this review, we discussed the overview of mesenchymal stem cells and induced pluripotent stem cells. We briefly present therapeutic approaches and COVID-19-related diseases using MSCs and iPSCs.

Manufacturing Mesenchymal Stromal Cells for the Treatment of Osteoarthritis in Canine Patients: Challenges and Recommendations

The recent interest in advanced biologic therapies in veterinary medicine has opened up opportunities for new treatment modalities with considerable clinical potential. Studies with mesenchymal stromal cells (MSCs) from animal species have focused on in vitro characterization (mostly following protocols developed for human application), experimental testing in controlled studies and clinical use in veterinary patients. The ability of MSCs to interact with the inflammatory environment through immunomodulatory and paracrine mechanisms makes them a good candidate for treatment of inflammatory musculoskeletal conditions in canine species. Analysis of existing data shows promising results in the treatment of canine hip dysplasia, osteoarthritis and rupture of the cranial cruciate ligament in both sport and companion animals. Despite the absence of clear regulatory frameworks for veterinary advanced therapy medicinal products, there has been an increase in the number of commercial cell-based products that are available for clinical applications, and currently the commercial use of veterinary MSC products has outpaced basic research on characterization of the cell product. In the absence of quality standards for MSCs for use in canine patients, their safety, clinical efficacy and production standards are uncertain, leading to a risk of poor product consistency. To deliver high-quality MSC products for veterinary use in the future, there are critical issues that need to be addressed. By translating standards and strategies applied in human MSC manufacturing to products for veterinary use, in a collaborative effort between stem cell scientists and veterinary researchers and surgeons, we hope to facilitate the development of quality standards. We point out critical issues that need to be addressed, including a much higher level of attention to cell characterization, manufacturing standards and release criteria. We provide a set of recommendations that will contribute to the standardization of cell manufacturing methods and better quality assurance.

Establishing a rabbit model of perianal fistulizing Crohn’s disease

BACKGROUND

Crohn's disease (CD) is a chronic nonspecific intestinal inflammatory disease. The aetiology and pathogenesis of CD are still unclear. Anal fistula is the main complication of CD and is a difficult problem to solve at present. The main limitation of developing new therapies is bound up with the short of preclinical security and effectiveness data. Therefore, an ideal animal model is needed to establish persistent anal fistula and an inflamed rectal mucosa.

AIM

To improve the induction method of colitis and establish a reliable and reproducible perianal fistulizing Crohn’s disease animal model to evaluate new treatment strategies.

METHODS

Twenty male New Zealand rabbits underwent rectal enema with different doses of 2,4,6-trinitrobenzene sulfonic acid to induce proctitis. Group A was treated with an improved equal interval small dose increasing method. The dosage of group B was constant. Seven days later, the rabbits underwent surgical creation of a transsphincteric fistula. Then, three rabbits were randomly selected from each group every 7 d to remove the seton from the fistula. The rabbits were examined by endoscopy every 7 days, and biopsy forceps were used to obtain tissue samples from the obvious colon lesions for histological analysis. The disease activity index (DAI), colonoscopy and histological scores were recorded. Perianal endoscopic ultrasonography (EUS) was used to evaluate the healing of fistulas.

RESULTS

Except for the DAI score, the colonoscopy and histological scores in group A were significantly higher than those in group B (P < 0.05). In the ideal model rabbit group, on the 7^th day after the removal of the seton, all animals had persistent lumens on EUS imaging, showing continuous full-thickness high signals. Histological inspection of the fistula showed acute and chronic inflammation, fibrosis, epithelialization and peripheral proctitis of the adjoining rectum.

CONCLUSION

The improved method of CD colitis induction successfully established a rabbit perianal fistula CD preclinical model, which was confirmed by endoscopy and pathology.

Efficacy and Safety of Mesenchymal Stem Cell Transplantation in the Treatment of Autoimmune Diseases (Rheumatoid Arthritis, Systemic Lupus Erythematosus, Inflammatory Bowel Disease, Multiple Sclerosis, and Ankylosing Spondylitis): A Systematic Review and Meta-Analysis of Randomized Controlled Trial

Objective

To evaluate the efficacy and safety of mesenchymal stem cell (MSC) transplantation in the treatment of autoimmune diseases.

Methods

The Chinese and English databases were searched for clinical research on the treatment of autoimmune diseases with mesenchymal stem cells. The search time range is from a self-built database to October 1, 2021. Two reviewers independently screened the literature according to the inclusion and exclusion criteria, extracted data, and evaluated the bias of the included studies. RevMan 5.3 analysis software was used for meta-analysis.

Results

A total of 18 RCTs involving 5 autoimmune diseases were included. The 5 autoimmune disease were rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), inflammatory bowel disease, ankylosing spondylitis, and multiple sclerosis. For RA, the current randomized controlled trials (RCTs) still believe that stem cell transplantation may reduce disease activity, improve the clinical symptoms (such as DAS28), and the percentage of CD4+CD 25+Foxp3+Tregs in the response group increased and the percentage of CD4+IL-17A+Th17 cells decreased. The total clinical effective rate of RA is 54%. For SLE, the results showed that mesenchymal stem cell transplantation may improve SLEDAI [-2.18 (-3.62, -0.75), P = 0.003], urine protein [-0.93 (-1.04, -0.81), P < 0.00001], and complement C3 [0.31 (0.19, 0.42), P < 0.00001]. For inflammatory bowel disease, the results showed that mesenchymal stem cell transplantation may improve clinical efficacy [2.50 (1.07, 5.84), P = 0.03]. For ankylosing spondylitis, MSC treatment for 6 months may increase the total effective rate; reduce erythrocyte sedimentation rate, intercellular adhesion molecules, and serum TNF-α; and improve pain and activity. For multiple sclerosis, the current research results are still controversial, so more RCTs are needed to amend or confirm the conclusions. No obvious adverse events of mesenchymal stem cell transplantation were found in all RCTs.

Conclusion

MSCs have a certain effect on different autoimmune diseases, but more RCTs are needed to further modify or confirm the conclusion.

Advanced Regenerative Medicine Strategies for Treatment of Perianal Fistula in Crohn's Disease

Regenerative medicine is an emerging therapeutic method that aims to reconstruct tissues and organs. This advanced therapeutic approach has demonstrated great potential in addressing the limitations of medical and surgical procedures for treating perineal fistula in patients with Crohn's disease. Recent developments in stem cell technology have led to a massive good manufacturing practices (GMPs) production of various stem cells, including mesenchymal and embryonic cells, along with induction of pluripotent stem cells to repair damaged tissues in the fistula. The recent advances in separation and purification of exosomes, as biologic nanovesicles carrying anti-inflammatory and regenerative agents, have made them powerful tools to treat this inflammatory disease. Further, tremendous advances in nanotechnology, biomaterials, and scaffold fabrication methods enable tissue engineering methods to synthesize tissue-like structures to assist surgical techniques. This review focuses on advanced regenerative-based methods including stem cell therapy, exosome therapy, and tissue engineering used in the treatment of perianal fistula. Relevant in vitro and in vivo studies and the latest innovations in implementation of regenerative medicine for this disease are also separately reviewed. Additionally, current challenges regarding implementation of g stem cells, exosomes, and tissue engineering methods for bridging the gaps between laboratory findings and clinic application will be discussed.

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.

Tracking of human embryonic stem cell-derived mesenchymal stem cells in premature ovarian failure model mice

Premature ovarian failure (POF) is defined by amenorrhea, hypoestrogenism, elevated gonadotropin levels, and infertility. Chemotherapeutic agents are the most gonadotoxic agents that lead to POF. Although some previous studies have presented that mesenchymal stem cells (MSCs) transplantation could rescue the ovary function of POF animal models through the paracrine pathway, these mechanisms require further investigation. However, mechanisms of embryonic stem cell-derived MSCs (ES-MSCs) therapeutic effects on POF animal models have not been fully investigated yet. This study aimed to evaluate the migration and distribution of ES-MSCs in a model of chemotherapy-induced POF. Female mice received intraperitoneal injections of cyclophosphamide (Cy) to induce POF. Then, MSCs were labeled with green fluorescent protein (GFP) in vitro and injected intravenously into POF mice, and the distribution of MSCs was dynamically monitored at 1 week after transplantation. We harvested the lungs, liver, spleen, ovaries, heart, and kidneys 1 week after transplantation. The sections of these tissues were observed under the fluorescent microscope. More than 70% MSCs were successfully labeled with GFP at 72 h after labeling. MSCs were uniformly distributed in multiple organs and tissues including lungs, liver, spleen, ovaries, heart, and kidneys of POF mice. In mice, at 1week after intravenous transplantation, GFP labeled ES-MSCs were observed in the lungs, liver, spleen, ovaries, heart, and kidneys of POF mice, and the number of GFP labeled ES-MSCs in lungs, ovaries, and heart were higher than that in the spleen, kidneys, and liver. Our results revealed intravenously implanted ES-MSCs could migrate into the various tissues in chemotherapy-induced damaged POF mice.

Magnetic Fe3 O4 @graphene oxide improves the therapeutic effects of embryonic stem cells on acute liver damage

OBJECTIVE

Acute liver failure is usually associated with inflammation and oxidation of hepatocytes and has high mortality and resource costs. Mesenchymal stem cell (MSCs) has occasionally been reported to have no beneficial effect due to poor transplantation and the survival of implanted cells. Recent studies showed that embryonic stem cell (ESC)-derived MSCs are an alternative for regenerative medicine. On the other hand, graphene-based nanostructures have proven useful in biomedicine. In this study, we investigated whether magnetic graphene oxide (MGO) improved the effects of ESC-MSC conditioned medium (CM) on protecting hepatocytes and stimulating the regeneration of damaged liver cells.

MATERIALS AND METHODS

To provide a rat model of acute liver failure, male rats were injected intraperitoneally with carbon tetrachloride (CCl4 ). The rats were randomly divided into six groups, namely control, sham, CCl4 , ESC-MSC-CM, MGO and ESC-MSC-CM + MGO. In the experimental groups, the rats received, depending on the group, 2 ml/kg body weight CCl4 and either ESC-MSC-CM with 5 × 106 MSCs or 300 μg/kg body weight MGO or both. Symptoms of acute liver failure appeared 4 days after the injection. All groups were compared and analysed both histologically and biochemically 4 days after the injection. Finally, the results of ESC-MSC-CM and MSC-CM were compared.

RESULTS

The results indicated that the use of MGO enhanced the effect of ESC-MSC-CM on reducing necrosis, inflammation, aspartate transaminase, alanine aminotransferase and alkaline phosphatase in the CCl4 -induced liver failure of the rat model. Also, the expression of vascular endothelial growth factor and matrix metalloproteinase-9 (MMP-9) was significantly upregulated after treatment with MGO. Also, the results showed that the ESC-MSC-CM has more efficient effective compared to MSC-CM.

CONCLUSION

Magnetic graphene oxide improved the hepatoprotective effects of ESC-MSC-CM on acute liver damage, probably by suppressing necrosis, apoptosis and inflammation of hepatocytes.

Drug delivery to the inflamed intestinal mucosa - targeting technologies and human cell culture models for better therapies of IBD

Current treatment strategies for inflammatory bowel disease (IBD) seek to alleviate the undesirable symptoms of the disorder. Despite the higher specificity of newer generation therapeutics, e.g. monoclonal antibodies, adverse effects still arise from their interference with non-specific systemic immune cascades. To circumvent such undesirable effects, both conventional and newer therapeutic options can benefit from various targeting strategies. Of course, both the development and the assessment of the efficiency of such targeted delivery systems necessitate the use of suitable in vivo and in vitro models representing relevant pathophysiological manifestations of the disorder. Accordingly, the current review seeks to provide a comprehensive discussion of the available preclinical models with emphasis on human in vitro models of IBD, along with their potentials and limitations. This is followed by an elaboration on the advancements in the field of biology- and nanotechnology-based targeted drug delivery systems and the potential rooms for improvement to facilitate their clinical translation.

Evaluation of animal models of Crohn's disease with anal fistula (Review)

Anal fistula is a common and serious complication of Crohn's disease (CD). A sufficiently suitable animal model that may be used to simulate this disease is yet to be established. The aim of the present review was to summarize the different characteristics and experimental methods of commonly used animal models of CD with anal fistula. Electronic databases were searched for studies reporting on the use of this type of animal model. A total of 234 related articles were retrieved, of which six articles met the inclusion criteria; these were used as references for the present review article. The characteristics of the animal models, the advantages and disadvantages of the modeling methods and the similarities with patients with CD and anal fistula were summarized and analyzed. The evidence suggests that a sufficiently suitable animal preclinical model requires to be established.

Human Hemangioblast-Derived Mesenchymal Stem Cells Promote Islet Engraftment in a Minimal Islet Mass Transplantation Model in Mice

Islet transplantation can restore glycemic control in patients with type 1 diabetes. Using this procedure, the early stages of engraftment are often crucial to long-term islet function, and outcomes are not always successful. Numerous studies have shown that mesenchymal stem cells (MSCs) facilitate islet graft function. However, experimental data can be inconsistent due to variables associated with MSC generation (including donor characteristics and tissue source), thus, demonstrating the need for a well-characterized and uniform cell product before translation to the clinic. Unlike bone marrow- or adipose tissue-derived MSCs, human embryonic stem cell-derived-MSCs (hESC-MSCs) offer an unlimited source of stable and highly-characterized cells that are easily scalable. Here, we studied the effects of human hemangioblast-derived mesenchymal cells (HMCs), (i.e., MSCs differentiated from hESCs using a hemangioblast intermediate), on islet cell transplantation using a minimal islet mass model. The co-transplantation of the HMCs allowed a mass of islets that was insufficient to correct diabetes on its own to restore glycemic control in all recipients. Our in vitro studies help to elucidate the mechanisms including reduction of cytokine stress by which the HMCs support islet graft protection in vivo. Derivation, stability, and scalability of the HMC source may offer unique advantages for clinical applications, including fewer islets needed for successful islet transplantation.

Dysbiosis in a canine model of human fistulizing Crohn's disease

Crohn's disease (CD) is a chronic immune-mediated inflammatory condition caused by the loss of mucosal tolerance toward the commensal microbiota. On average, 29.5% and 42.7% CD patients experience perianal complications at 10 and 20 y after diagnosis, respectively. Perianal CD (pCD) result in high disease burden, diminished quality of life, and elevated health-care costs. Overall pCD are predictors of poor long-term outcomes. Animal models of gut inflammation have failed to fully recapitulate the human manifestations of fistulizing CD. Here, we evaluated dogs with spontaneous canine anal furunculosis (CAF), a disease with clinical similarities to pCD, as a surrogate model for understanding the microbial contribution of human pCD pathophysiology. By comparing the gut microbiomes between dogs suffering from CAF (CAF dogs) and healthy dogs, we show CAF-dog microbiomes are either very dissimilar (dysbiotic) or similar (healthy-like), yet unique, to healthy dog's microbiomes. Compared to healthy or healthy-like CAF microbiomes, dysbiotic CAF microbiomes showed an increased abundance of Bacteroides vulgatus and Escherichia coli and a decreased abundance of Megamonas species and Prevotella copri. Our results mirror what have been reported in previous microbiome studies of patients with CD; particularly, CAF dogs exhibited two distinct microbiome composition: dysbiotic and healthy-like, with determinant bacterial taxa such as E. coli and P. copri that overlap what it has been found on their human counterpart. Thus, our results support the use of CAF dogs as a surrogate model to advance our understanding of microbial dynamics in pCD.

Challenges of stem cell therapies in companion animal practice

Regenerative medicine using stem cells from various sources are emerging treatment modality in several refractory diseases in veterinary medicine. It is well-known that stem cells can differentiate into specific cell types, self-renew, and regenerate. In addition, the unique immunomodulatory effects of stem cells have made stem cell transplantation a promising option for treating a wide range of disease and injuries. Recently, the medical demands for companion animals have been rapidly increasing, and certain disease conditions require alternative treatment options. In this review, we focused on stem cell application research in companion animals including experimental models, case reports and clinical trials in dogs and cats. The clinical studies and therapeutic protocols were categorized, evaluated and summarized according to the organ systems involved. The results indicate that evidence for the effectiveness of cell-based treatment in specific diseases or organ systems is not yet conclusive. Nonetheless, stem cell therapy may be a realistic treatment option in the near future, therefore, considerable efforts are needed to find optimized cell sources, cell numbers and delivery methods in order to standardize treatment methods and evaluation processes.

Canine atopic dermatitis attenuated by mesenchymal stem cells

Objective:

To evaluate the use of mesenchymal stem cells (MSCs) in the attenuation of canine atopic dermatitis (AD).

Materials and methods:

Sixteen dogs were selected and divided into three groups, mild, moderate, and severe, according to the Canine Atopic Dermatitis Extent and Severity Index (CADESI-4). They were evaluated for 82 days. The protocol recommended in this experiment was to inject 2 × 10⁶/kg bodyweight of MSC’s in all groups by the intravenous route with intervals of applications of 21 days. The degree of pruritus was evaluated by examining the visual analog scale, the CADESI-4, the histopathology of the skin, hematological and biochemical parameters, the pyogenic effect of MSCs, and the thickness of the epidermis.

Results:

There was a significant difference in the reduction of epidermal thickness in the moderate and severe groups. Hematological, biochemical, and body temperature parameters remained within normal limits for the species with no side effects

Conclusion:

MSCs attenuated the clinical signs of AD.

Intravenous Infusion of Umbilical Cord Mesenchymal Stem Cells Maintains and Partially Improves Visual Function in Patients with Advanced Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a hereditary retinal degeneration disease with no effective therapeutic approaches. Inflammatory and immune disorders are thought to play an important role in the pathogenesis of RP. Human umbilical cord mesenchymal stem cells (UCMSCs), with multiple biological functions such as anti-inflammation and immunoregulation, have been applied in different systemic diseases. We conducted a phase I/II clinical trial aiming to evaluate the safety and efficacy of intravenous administration of UCMSCs in advanced RP patients. All 32 subjects were intravenously infused with one dose of 10⁸ UCMSCs and were followed up for 12 months. No serious local or systemic adverse effects occurred in the whole follow-up. Most patients improved their best corrected visual acuity (BCVA) in the first 3 months. The proportions of patients with improved or maintained BCVA were 96.9%, 95.3%, 93.8%, 95.4%, 90.6%, and 90.6% at the 1st, 2nd, 3rd, 6th, 9th, and 12th month follow-up, respectively. Most of the patients (81.3%) maintained or improved their visual acuities for 12 months. The average NEI VFQ-25 questionnaire scores were significantly improved at the third month (P < 0.05). The average visual field sensitivity and flash visual evoked potential showed no significant difference (P = 0.185, P = 0.711). Our results indicated that the intravenous infusion of UCMSCs was safe for advanced RP patients. Most of the patients improved or maintained their visual functions in a long term. The life qualities were improved significantly in the first 3 months, suggesting that the intravenous infusion of UCMSCs may be a promising therapeutic approach for advanced RP patients.

Extracellular vesicles derived from human ES-MSCs protect retinal ganglion cells and preserve retinal function in a rodent model of optic nerve injury

Background

Retinal and/or optic nerve injury is one of the leading causes of blindness due to retinal ganglion cell (RGC) degeneration. There have been extensive efforts to suppress this neurodegeneration. Various somatic tissue-derived mesenchymal stem cells (MSCs) demonstrated significant neuroprotective and axogenic effects on RGCs. An alternative source of MSCs could be human embryonic stem cells (ES-MSCs), which proliferate faster, express lower levels of inflammatory cytokines, and are capable of immune modulation. It has been demonstrated that MSCs secrete factors or extracellular vesicles that may heal the injury. However, possible therapeutic effects and underlying mechanism of human ES-MSC extracellular vesicles (EVs) on optic nerve injury have not been assessed.

Methods

EVs were isolated from human ES-MSCs. Then, ES-MSC EV was applied to an optic nerve crush (ONC) mouse model. Immunohistofluorescence, retro- and anterograde tracing of RGCs, Western blot, tauopathy in RGCs, and function assessments were performed during 2-month post-treatment to evaluate ONC improvement and underlying mechanism of human ES-MSC EV in in vivo.

Results

We found that the ES-MSC EV significantly improved Brn3a+ RGCs survival and retro- and anterograde tracing of RGCs, while preventing retinal nerve fiber layer (RNFL) degenerative thinning compared to the vehicle group. The EVs also significantly promoted GAP43+ axon counts in the optic nerve and improved cognitive visual behavior. Furthermore, cis p-tau, a central mediator of neurodegeneration in the injured RGCs, is detectable after the ONC at the early stages demonstrated tauopathy in RGCs. Notably, after EV treatment cis p-tau was downregulated.

Conclusions

Our findings propose that human ES-MSC EVs, as an off-the-shelf and cell-free product, may have profound clinical implications in treating injured RGCs and degenerative ocular disease. Moreover, the possible mechanisms of human ES-MSC EV are related to the rescue of tauopathy process of RGC degeneration.

Mesenchymal stem cells therapy in companion animals: useful for immune-mediated diseases?

Mesenchymal stem cells are multipotent cells, with capacity for self-renewal and differentiation into tissues of mesodermal origin. These cells are possible therapeutic agents for autoimmune disorders, since they present remarkable immunomodulatory ability.The increase of immune-mediated diseases in veterinary medicine has led to a growing interest in the research of these disorders and their medical treatment. Conventional immunomodulatory drug therapy such as glucocorticoids or other novel therapies such as cyclosporine or monoclonal antibodies are associated with numerous side effects that limit its long-term use, leading to the need for developing new therapeutic strategies that can be more effective and safe.The aim of this review is to provide a critical overview about the therapeutic potential of these cells in the treatment of some autoimmune disorders (canine atopic dermatitis, feline chronic gingivostomatitis, inflammatory bowel disease and feline asthma) compared with their conventional treatment.Mesenchymal stem cell-based therapy in autoimmune diseases has been showing that this approach can ameliorate clinical signs or even cause remission in most animals, with the exception of canine atopic dermatitis in which little to no improvement was observed.Although mesenchymal stem cells present a promising future in the treatment of most of these disorders, the variability in the outcomes of some clinical trials has led to the current controversy among authors regarding their efficacy. Mesenchymal stem cell-based therapy is currently requiring a deeper and detailed analysis that allows its standardization and better adaptation to the intended therapeutic results, in order to overcome current limitations in future trials.

Renewed assessment of the risk of emergent advanced cell therapies to transmit neuroproteinopathies

The inadvertent transmission of long incubating, untreatable and fatal neurodegenerative prionopathies, notably iatrogenic Creutzfeldt–Jakob disease, following transplantation of cadaver-derived corneas, pituitary growth, hormones and dura mater, constitutes a historical precedent which has underpinned the application of precautionary principles to modern day advanced cell therapies. To date these have been reflected by geographic or medical history risk-based deferral of tissue donors. Emergent understanding of other prion-like proteinopathies, their potential independence from prions as a transmissible agent and the variable capability of scalably manufacturable stem cells and derivatives to take up and clear or to propagate prions, substantiate further commitment to qualifying neurodegenerative proteinopathy transmission risks. This is especially so for those involving direct or facilitated access to a recipient’s brain or connected visual or nervous system such as for the treatment of stroke, retinal and adult onset neurodegenerative diseases, treatments for which have already commenced. In this review, we assess the prospective global dissemination of advanced cell therapies founded on transplantation or exposure to allogeneic human cells, recap lessons learned from the historical precedents of CJD transmission and review recent advances and current limits in understanding of prion and other neurodegenerative disease prion-like susceptibility and transmission. From these we propose grounds for a reassessment of the risks of emergent advanced cell therapies to transmit neuroproteinopathies and suggestions to ACT developers and regulators for risk mitigation and extension of criteria for deferrals.

Mesenchymal stem cell basic research and applications in dog medicine

The stem cells, owing to their special characteristics like self-renewal, multiplication, homing, immunomodulation, anti-inflammatory, and dedifferentiation are considered to carry an "all-in-one-solution" for diverse clinical problems. However, the limited understanding of cellular physiology currently limits their definitive therapeutic use. Among various stem cell types, currently mesenchymal stem cells are extensively studied for dog clinical applications owing to their readily available sources, easy harvesting, and ability to differentiate both into mesodermal, as well as extramesodermal tissues. The isolated, culture expanded, and characterized cells have been applied both at preclinical as well as clinical settings in dogs with variable but mostly positive results. The results, though positive, are currently inconclusive and demands further intensive research on the properties and their dependence on the applications. Further, numerous clinical conditions of dog resemble to that of human counterparts and thus, if proved rewarding in the former may act as basis of therapy for the latter. The current review throws some light on dog mesenchymal stem cell properties and their potential therapeutic applications.

Minimally Invasive and Regenerative Therapeutics

Advances in biomaterial synthesis and fabrication, stem cell biology, bioimaging, microsurgery procedures, and microscale technologies have made minimally invasive therapeutics a viable tool in regenerative medicine. Therapeutics, herein defined as cells, biomaterials, biomolecules, and their combinations, can be delivered in a minimally invasive way to regenerate different tissues in the body, such as bone, cartilage, pancreas, cardiac, skeletal muscle, liver, skin, and neural tissues. Sophisticated methods of tracking, sensing, and stimulation of therapeutics in vivo using nano-biomaterials and soft bioelectronic devices provide great opportunities to further develop minimally invasive and regenerative therapeutics (MIRET). In general, minimally invasive delivery methods offer high yield with low risk of complications and reduced costs compared to conventional delivery methods. Here, minimally invasive approaches for delivering regenerative therapeutics into the body are reviewed. The use of MIRET to treat different tissues and organs is described. Although some clinical trials have been performed using MIRET, it is hoped that such therapeutics find wider applications to treat patients. Finally, some future perspective and challenges for this emerging field are highlighted.

Human cardiomyocytes undergo enhanced maturation in embryonic stem cell-derived organoid transplants

Human cardiomyocytes (CM) differentiated from pluripotent stem cells (PSCs) are relatively immature when generated in two-dimensional (2D) in vitro cultures, which limits their biomedical applications. Here, we devised a strategy to enhance maturation of human CM in vitro by assembly of three-dimensional (3D) cardiac organoids (CO) containing human embryonic stem cell-derived cardiac progenitor cells (hESC-CPCs), endothelial cells (ECs), and mesenchymal stem cells (MSCs). In contrast to corresponding 2D cultures, 3D CO not only developed into structures containing spontaneously beating CM, but also showed enhanced maturity as indicated by increased expressions of sarcomere and ion channel genes and reduced proliferation. Heterotopic implantation of CO into the peritoneal cavity of immunodeficient mice induced neovascularization, and further stimulated upregulation of genes coding for the contractile apparatus, Ca²⁺ handling and ion channel proteins. In addition, CM in implanted CO were characterized by a more mature ultrastructure compared to CM implanted without CO support. Functional analysis revealed the presence of working cardiomyocytes in both in vivo and ex ovo chorioallantoic membrane implanted CO. Our results demonstrate that cultivation in 3D CO and subsequent heterotopic implantation enhance maturation of CM towards an adult-like phenotype. We reason that CO-derived CM represent an attractive source for drug discovery and other biomedical applications.

Generation and Applications of Induced Pluripotent Stem Cell-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are adult stem cells with fibroblast-like morphology and isolated from the bone marrow via plastic adhesion. Their multipotency and immunoregulatory properties make MSCs possible therapeutic agents, and an increasing number of publications and clinical trials have highlighted their potential in regenerative medicine. However, the finite proliferative capacity of MSCs limits their scalability and global dissemination as a standardized therapeutic product. Furthermore, adult tissue provenance could constrain accessibility, impinge on cellular potency, and incur greater exposure to disease-causing pathogens based on the donor. These issues could be circumvented by the derivation of MSCs from pluripotent stem cells. In this paper, we review methods that induce and characterize MSCs derived from induced pluripotent stem cells (iPSCs) and introduce MSC applications to disease modeling, pathogenic mechanisms, and drug discovery. We also discuss the potential applications of MSCs in regenerative medicine including cell-based therapies and issues that should be overcome before iPSC-derived MSC therapy will be applied in the clinic.

Current Status of Canine Umbilical Cord Blood-Derived Mesenchymal Stem Cells in Veterinary Medicine

Stem cell therapy has prompted the expansion of veterinary medicine both experimentally and clinically, with the potential to contribute to contemporary treatment strategies for various diseases and conditions for which limited or no therapeutic options are presently available. Although the application of various types of stem cells, such as bone marrow-derived mesenchymal stem cells (BM-MSCs), adipose tissue-derived mesenchymal stem cells (AT-MSCs), and umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs), has promising potential to improve the health of different species, it is crucial that the benefits and drawbacks are completely evaluated before use. Umbilical cord blood (UCB) is a rich source of stem cells; nonetheless, isolation of mesenchymal stem cells (MSCs) from UCB presents technical challenges. Although MSCs have been isolated from UCB of diverse species such as human, equine, sheep, goat, and canine, there are inherent limitations of using UCB from these species for the expansion of MSCs. In this review, we investigated canine UCB (cUCB) and compared it with UCB from other species by reviewing recent articles published from February 2003 to June 2017 to gain an understanding of the limitations of cUCB in the acquisition of MSCs and to determine other suitable sources for the isolation of MSCs from canine. Our review indicates that cUCB is not an ideal source of MSCs because of insufficient volume and ethical issues. However, canine reproductive organs discarded during neutering may help broaden our understanding of effective isolation of MSCs. We recommend exploring canine reproductive and adipose tissue rather than UCB to fulfill the current need in veterinary medicine for the well-designed and ethically approved source of MSCs.

Canine mesenchymal stem cells treated with TNF-α and IFN-γ enhance anti-inflammatory effects through the COX-2/PGE2 pathway

Mesenchymal stem cells (MSCs) have been used in studies on treatment of various diseases, and their application to immune-mediated diseases has garnered interest. Various methods for enhancing the immunomodulation effect of human MSCs have been used; however, similar approaches for canine MSCs are relatively unexplored. Accordingly, we evaluated immunomodulatory effects and mechanisms in canine MSCs treated with TNF-α and IFN-γ. Lipopolysaccharide (LPS)-stimulated RAW 264.7 cells were incubated with the conditioned media (CM) from canine MSCs for 48 h. Expression of RNA was assessed by quantitative reverse transcription PCR (qRT-PCR), and protein levels were assessed by western blot. Expression of inducible nitric oxide synthase (iNOS), IL-6 and IL-1β was significantly (one-way ANOVA) decreased in LPS-stimulated RAW 264.7 cells incubated with CM from canine MSCs compared to that in LPS-stimulated RAW 264.7 cells alone. Furthermore, anti-inflammatory effects of TNF-α- and IFN-γ-primed canine MSCs were significantly increased compared with those of naïve canine MSCs. Expression of cyclooxygenase 2 (COX-2) and prostaglandin E₂ (PGE₂) were likewise significantly increased in primed canine MSCs. The level of iNOS protein in LPS-stimulated RAW 264.7 cells incubated with CM from the primed canine MSCs was decreased, but it increased when the cells were treated with NS-398(PGE₂ inhibitor). In conclusion, compared with naïve canine MSCs, cells primed with TNF-α and IFN-γ cause a greater reduction in release of anti-inflammatory cytokines from LPS-stimulated RAW 264.7 cells; the mechanism is upregulation of the COX-2/PGE₂ pathway.

Safety and immune regulatory properties of canine induced pluripotent stem cell-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) exhibit broad immune modulatory activity in vivo and can suppress T cell proliferation and dendritic cell activation in vitro. Currently, most MSC for clinical usage are derived from younger donors, due to ease of procurement and to the superior immune modulatory activity. However, the use of MSC from multiple unrelated donors makes it difficult to standardize study results and compare outcomes between different clinical trials. One solution is the use of MSC derived from induced pluripotent stem cells (iPSC); as iPSC-derived MSC have nearly unlimited proliferative potential and exhibit in vitro phenotypic stability. Given the value of dogs as a spontaneous disease model for pre-clinical evaluation of stem cell therapeutics, we investigated the functional properties of canine iPSC-derived MSC (iMSC), including immune modulatory properties and potential for teratoma formation. We found that canine iMSC downregulated expression of pluripotency genes and appeared morphologically similar to conventional MSC. Importantly, iMSC retained a stable phenotype after multiple passages, did not form teratomas in immune deficient mice, and did not induce tumor formation in dogs following systemic injection. We concluded therefore that iMSC were phenotypically stable, immunologically potent, safe with respect to tumor formation, and represented an important new source of cells for therapeutic modulation of inflammatory disorders.

Pluripotent Stem Cells as a Robust Source of Mesenchymal Stem Cells

Mesenchymal stem cells (MSC) have been extensively studied over the past years for the treatment of different diseases. Most of the ongoing clinical trials currently involve the use of MSC derived from adult tissues. This source may have some limitations, particularly with therapies that may require extensive and repetitive cell dosage. However, nowadays, there is a staggering growth in literature on a new source of MSC. There is now increasing evidence about the mesenchymal differentiation from pluripotent stem cell (PSC). Here, we summarize the current knowledge of pluripotent-derived mesenchymal stem cells (PD-MSC). We present a historical perspective on the subject, and then discuss some critical questions that remain unanswered.

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.

Human Embryonic Stem Cell-Derived Mesenchymal Stromal Cells Decrease the Development of Severe Experimental Autoimmune Uveitis in B10.RIII Mice

PURPOSE

We investigated the effect of exogenously administered human embryonic stem cell-derived mesenchymal stromal cells (hESC-MSCs) in experimental autoimmune uveitis (EAU) in B10.RIII mice, a murine model of severe uveitis.

METHODS

B10.RIII mice were immunized with an uveitogenic peptide, and intraperitoneal injections of 5 million hESC-MSCs per animal were given on the same day. Behavioral light sensitivity assays, histological evaluation, cytokine production, and regulatory T cells were analyzed at the peak of the disease.

RESULTS

Histological and behavioral evidence demonstrated that early systemic treatment with hESC-MSCs decreases the development of severe EAU in B10.RIII mice. hESC-MSCs suppress Th17 and upregulate Th1 and Th2 responses as well as IL-2 and GM-CSF in splenocytes from hESC-MSC-treated mice.

CONCLUSIONS

MSCs that originate from hESC decrease the development of severe EAU in B10.RIII mice, likely through systemic immune modulation. Further investigation is needed to determine any potential effect on active EAU.

Mechanisms of Immune Suppression Utilized by Canine Adipose and Bone Marrow-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) from rodents and humans have been shown to suppress T cells by distinct primary pathways, with nitric oxide (NO)-dependent pathways dominating in rodents and indoleamine 2,3-deoxygenase (IDO)-dependent pathways dominating in humans. However, the immune suppressive pathways utilized by canine MSC have not been thoroughly studied, nor have bone marrow-derived MSC (BM-MSC) and adipose-derived MSC (Ad-MSC) been directly compared for their immune modulatory potency or pathway utilization. Therefore, canine BM-MSC and Ad-MSC were generated in vitro and their potency in suppressing T cell proliferation and cytokine production was compared, and differential gene expression. Mechanisms of T cells suppression were also investigated for both MSC types. We found that BM-MSC and Ad-MSC were roughly equivalent in terms of their ability to suppress T cell activation. However, the two MSC types used both shared and distinct biochemical pathways to suppress T cell activation. Ad-MSC utilized TGF-β signaling pathways and adenosine signaling to suppress T cell activation, whereas BM-MSC used cyclooxygenase, TGF-β and adenosine signaling pathways to suppress T cell activation. These results indicate that canine MSC are distinct from human and rodent MSC terms of their immune suppressive pathways, relying primarily on cyclooxygenase and TGF-β pathways for T cell suppression, rather than on NO or IDO-mediated pathways.

Effect of Secreted Molecules of Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells on Acute Hepatic Failure Model

Adult tissue-derived mesenchymal stem cells (MSCs) show tremendous promise for a wide array of therapeutic applications predominantly through paracrine activity. Recent reports showed that human embryonic stem cell (ESC)-derived MSCs are an alternative for regenerative cellular therapy due to manufacturing large quantities of MSCs from a single donor. However, no study has been reported to uncover the secretome of human ESC-MSCs as treatment of an acute liver failure (ALF) mouse model. We demonstrated that human ESC-MSCs showed similar morphology and cell surface markers compared with bone marrow-derived MSCs. ESC-MSCs exhibited a higher growth rate during early in vitro expansion, along with adipogenic and osteogenic differentiation potential. Treatment with ESC-MSC-conditioned medium (CM) led to statistically significant enhancement of primary hepatocyte viability and increased immunomodulatory interleukin-10 secretion from lipopolysaccharide-induced human blood mononuclear cells. Analysis of the MSCs secretome by a protein array screen showed an association between higher frequencies of secretory proteins such as vascular endothelial growth factor (VEGF) and regulation of cell proliferation, cell migration, the development process, immune system process, and apoptosis. In this thioacetamide-induced mouse model of acute liver injury, we observed that systemic infusion of VEGF led to significant survival. These data have provided the first experimental evidence of the therapeutic potential of human ESC-MSC-derived molecules. These molecules show trophic support to hepatocytes, which potentially creates new avenues for the treatment of ALF, as an inflammatory condition.

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.