Investigating cell therapy for inflammatory bowel disease

Interplay between inflammatory bowel disease therapeutics and the gut microbiome reveals opportunities for novel treatment approaches

Inflammatory bowel disease (IBD) is a complex heterogeneous disorder defined by recurring chronic inflammation of the gastrointestinal tract, attributed to a combination of factors including genetic susceptibility, altered immune response, a shift in microbial composition/microbial insults (infection/exposure), and environmental influences. Therapeutics generally used to treat IBD mainly focus on the immune response and include non-specific anti-inflammatory and immunosuppressive therapeutics and targeted therapeutics aimed at specific components of the immune system. Other therapies include exclusive enteral nutrition and emerging stem cell therapies. However, in recent years, scientists have begun to examine the interplay between these therapeutics and the gut microbiome, and we present this information here. Many of these therapeutics are associated with alterations to gut microbiome composition and functionality, often driving it toward a "healthier profile" and preclinical studies have revealed that such alterations can play an important role in therapeutic efficacy. The gut microbiome can also improve or hinder IBD therapeutic efficacy or generate undesirable metabolites. For certain IBD therapeutics, the microbiome composition, particularly before treatment, may serve as a biomarker of therapeutic efficacy. Utilising this information and manipulating the interactions between the gut microbiome and IBD therapeutics may enhance treatment outcomes in the future and bring about new opportunities for personalised, precision medicine.

3D multicellular systems in disease modelling: From organoids to organ-on-chip

Cell-cell interactions underlay organ formation and function during homeostasis. Changes in communication between cells and their surrounding microenvironment are a feature of numerous human diseases, including metabolic disease and neurological disorders. In the past decade, cross-disciplinary research has been conducted to engineer novel synthetic multicellular organ systems in 3D, including organoids, assembloids, and organ-on-chip models. These model systems, composed of distinct cell types, satisfy the need for a better understanding of complex biological interactions and mechanisms underpinning diseases. In this review, we discuss the emerging field of building 3D multicellular systems and their application for modelling the cellular interactions at play in diseases. We report recent experimental and computational approaches for capturing cell-cell interactions as well as progress in bioengineering approaches for recapitulating these complexities ex vivo. Finally, we explore the value of developing such multicellular systems for modelling metabolic, intestinal, and neurological disorders as major examples of multisystemic diseases, we discuss the advantages and disadvantages of the different approaches and provide some recommendations for further advancing the field.

Inflammatory Bowel Disease Treatments and Predictive Biomarkers of Therapeutic Response

Inflammatory bowel disease (IBD) is a chronic immune-mediated inflammation of the gastrointestinal tract with a highly heterogeneous presentation. It has a relapsing and remitting clinical course that necessitates lifelong monitoring and treatment. Although the availability of a variety of effective therapeutic options including immunomodulators and biologics (such as TNF, CAM inhibitors) has led to a paradigm shift in the treatment outcomes and clinical management of IBD patients, some patients still either fail to respond or lose their responsiveness to therapy over time. Therefore, according to the recent Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE-II) recommendations, continuous disease monitoring from symptomatic relief to endoscopic healing along with short- and long-term therapeutic responses are critical for providing IBD patients with a tailored therapy algorithm. Moreover, considering the high unmet need for novel therapeutic approaches for IBD patients, various new modulators of cytokine signaling events (for example, JAK/TYK inhibitors), inhibitors of cytokines (for example IL-12/IL-23, IL-22, IL-36, and IL-6 inhibitors), anti-adhesion and migration strategies (for example, β7 integrin, sphingosine 1-phosphate receptors, and stem cells), as well as microbial-based therapeutics to decolonize the bed buds (for example, fecal microbiota transplantation and bacterial inhibitors) are currently being evaluated in different phases of controlled clinical trials. This review aims to offer a comprehensive overview of available treatment options and emerging therapeutic approaches for IBD patients. Furthermore, predictive biomarkers for monitoring the therapeutic response to different IBD therapies are also discussed.

Bovine colostrum derived-exosomes prevent dextran sulfate sodium-induced intestinal colitis via suppression of inflammation and oxidative stress

Despite the rise in the global burden of inflammatory bowel disease, there is a lack of safe and effective therapies that can meet the needs of clinical patients. In this study, we investigated the beneficial effects of bovine milk, especially colostrum-derived exosomes (Col-exo) in a murine model of ulcerative colitis induced by dextran sodium sulfate (DSS). Col-exo activated the proliferation of colonic epithelial cells and macrophages, and created an environment to relieve inflammation by effectively removing reactive oxygen species and regulating the expression of immune cytokines. Besides, Col-exo could pass through the gastrointestinal tract intact and efficiently deliver bioactive cargoes to the stomach, small intestine, and colon. Our results showed that oral gavage of Col-exo can alleviate colitis symptoms including weight loss, gastrointestinal bleeding, and chronic diarrhea by modulating intestinal inflammatory immune responses. Overall, bovine colostrum-derived exosomes with excellent structural and functional stability may offer great potential as natural therapeutics for the recovery of colitis.

Treatment of Inflammatory Bowel Disease: A Comprehensive Review

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

Exosomes in Inflammatory Bowel Disease: What Have We Learned So Far?

Inflammatory bowel disease (IBD) is an immune-mediated chronic inflammatory disease. Although the etiology is uncertain, there is marked disbalance of mucosal immune responses in part shaped by genetic susceptibility and intestinal microbial dysbiosis. Suppressing inflammatory activity adequately and maintaining this suppression are the main goals of current therapies. However, corticosteroids are only suitable for therapy of active disease, and the effects of immunosuppressive agents are mainly limited to maintenance of remission. Biologics have become widely available and provide therapeutic benefits to IBD patients. However, only a part of patients benefits from them. Thus, there is an urgent need for the development of new substances in the therapy of IBD. Exosomes are nanosized lipid vesicles identified recently. They are secreted from all living cells and then distributed in various human body fluids. The components, such as microRNAs and functional proteins, secreted by exosomes in different cells have been reported to be involved in the pathogenesis of IBD. Therefore, exosomes have the potential to become appealing particles in treating IBD as a cell-free therapeutic approach as well as biomarkers for diagnosis and monitoring disease status. Further studies are needed to investigate the practicality, safety and desirable effects of exosomes in clinical applications in IBD.

BMP Antagonists Secreted by Mesenchymal Stromal Cells Improve Colonic Organoid Formation: Application for the Treatment of Radiation-induced Injury

Radiation therapy is crucial in the therapeutic arsenal to cure cancers; however, non-neoplastic tissues around an abdominopelvic tumor can be damaged by ionizing radiation. In particular, the radio-induced death of highly proliferative stem/progenitor cells of the colonic mucosa could induce severe ulcers. The importance of sequelae for patients with gastrointestinal complications after radiotherapy and the absence of satisfactory management has opened the field to the testing of innovative treatments. The aim of this study was to use adult epithelial cells from the colon, to reduce colonic injuries in an animal model reproducing radiation damage observed in patients. We demonstrated that transplanted in vitro-amplified epithelial cells from colonic organoids (ECO) of C57/Bl6 mice expressing green fluorescent protein implant, proliferate, and differentiate in irradiated mucosa and reduce ulcer size. To improve the therapeutic benefit of ECO-based treatment with clinical translatability, we performed co-injection of ECO with mesenchymal stromal cells (MSCs), cells involved in niche function and widely used in clinical trials. We observed in vivo an improvement of the therapeutic benefit and in vitro analysis highlighted that co-culture of MSCs with ECO increases the number, proliferation, and size of colonic organoids. We also demonstrated, using gene expression analysis and siRNA inhibition, the involvement of bone morphogenetic protein antagonists in MSC-induced organoid formation. This study provides evidence of the potential of ECO to limit late radiation effects on the colon and opens perspectives on combined strategies to improve their amplification abilities and therapeutic effects.

Inflammatory bowel disease: Therapeutic limitations and prospective of the stem cell therapy

Inflammatory bowel disease (IBD), consisting primarily of ulcerative colitis and Crohn’s disease, is a group of debilitating auto-immune disorders, which also increases the risk of colitis-associated cancer. However, due to the chronic nature of the disease and inconsistent treatment outcomes of current anti-IBD drugs (e.g., approximately 30% non-responders to anti-TNFα agents), and related serious side effects, about half of all IBD patients (in millions) turn to alternative treatment options. In this regard, mucosal healing is gaining acceptance as a measure of disease activity in IBD patients as recent studies have correlated the success of mucosal healing with improved prognosis. However, despite the increasing clinical realization of the significance of the concept of mucosal healing, its regulation and means of therapeutic targeting remain largely unclear. Here, stem-cell therapy, which uses hematopoietic stem cells or mesenchymal stem cells, remains a promising option. Stem cells are the pluripotent cells with ability to differentiate into the epithelial and/or immune-modulatory cells. The over-reaching concept is that the stem cells can migrate to the damaged areas of the intestine to provide curative help in the mucosal healing process. Moreover, by differentiating into the mature intestinal epithelial cells, the stem cells also help in restoring the barrier integrity of the intestinal lining and hence prevent the immunomodulatory induction, the root cause of the IBD. In this article, we elaborate upon the current status of the clinical management of IBD and potential role of the stem cell therapy in improving IBD therapy and patient’s quality of life.

Potential methods for improving the efficacy of mesenchymal stem cells in the treatment of inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are a group of chronic recurrent gastrointestinal inflammatory diseases, including ulcerative colitis (UC), Crohn's disease (CD) and IBD unclassified. The pathogenesis may be related to the mucosal immune dysfunction in genetically susceptible hosts affected by environmental factors. Current therapeutic agents mainly include aminosalicylates, corticosteroids, immunosuppressive drugs and novel biological agents. The purpose of treatment is to suppress inflammation and prevent irreversible structural damage. However, long-term application of these drugs may lead to multiple adverse effects and is not always effective. Mesenchymal stem cells (MSCs) are multipotent progenitors with low immunogenicity, which can be obtained and expanded easily. They play an important role in regulating immune responses and repairing damaged tissues in vivo. Therefore, MSCs are considered to be a promising option for the treatment of IBD. Nonetheless, there are many factors that can reduce the efficacy of MSCs, such as gradual deterioration of functional stem cells with age, low recruitment and persistence in vivo and different routes of administration. In recent years, researchers have been able to improve the efficacy of MSCs by pretreatment, genetic modification or co-application with other substances, as well as using different tissue-derived cells, administration methods or doses. This article reviews these methods to provide references for more effective application of MSCs in the treatment of IBD in the future.

Perspectives on Current and Novel Treatments for Inflammatory Bowel Disease

New therapeutic strategies in inflammatory bowel disease (IBD) have shifted from symptom control towards treat-to-target algorithms in order to optimize treatment results. The treatment of IBD has evolved with the development of tumor necrosis factor-α inhibitors beyond the conventional therapies. In spite of their long-term effectiveness, many patients do not respond to or cannot sustain treatment with these drugs, which have various side effects. Therefore, the development of new drugs targeting specific pathways in the pathogenesis of IBD has become necessary. Some novel biologics and small molecule drugs have shown potential in IBD clinical trials, providing safe and effective results. In addition, clinicians are now trying to target the dysbiotic microbiome of patients with IBD using fecal microbiota transplantation. New tools such as stem cells have also been developed. The available therapeutic options for IBD are expanding rapidly. In the next few years, physicians will face an unprecedented number of options when choosing the best treatments for patients with IBD. This review provides an overview of recent advances in IBD treatment options.

Organoid-based regenerative medicine for inflammatory bowel disease

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

Emerging treatments for inflammatory bowel disease

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is characterized by chronic inflammation, a relapsing and remitting clinical course, requirement for lifelong medication and often, significant morbidity. While multiple effective therapeutic options exist for the treatment of IBD, a proportion of patients will either fail to respond or lose response to therapy. Advances in therapeutics, such as the gut-specific anti-integrins, now offer patients an alternative option to systemic immunosuppression. Anti-interleukin 12 (anti-IL-12)/IL-23 agents offer new and effective treatment options for CD, while the oral small molecules now offer an oral alternative for the treatment of moderate-to-severe disease, previously requiring subcutaneous injection or intravenous infusion. Alternatives to pharmacological treatment such as stem-cell transplant and faecal microbiota transplant are also showing some promise in the treatment of both CD and UC.

Human umbilical cord mesenchymal stem cells alleviate inflammatory bowel disease by inhibiting ERK phosphorylation in neutrophils

Inflammatory bowel disease (IBD) can be caused by a variety of factors, including hereditary and environmental influences, that lead to dysfunction of the intestinal immune system. Mesenchymal stem cells (MSCs) exhibit important regulatory roles in relieving inflammation and repairing damaged tissues. Although neutrophils are important participants in the development of inflammatory reactions, they are also essential for maintaining intestinal balance during the process of mitigation of IBD by MSCs. Here, we constructed a dextran sulfate sodium (DSS)-induced mouse IBD model and evaluated the effects of treatment with human umbilical cord MSCs. Mouse body weight, faecal traits, colon/spleen gross morphology, tissue histology and immunohistochemical staining, and inflammatory factors were analysed. Magnetic beads were used to sort infiltrating neutrophils from intestinal tissues, and their phenotypes were identified. The neutrophil inflammatory environment was also simulated in vitro, and signalling pathways involved in MSC regulation of neutrophil phenotype were analysed. Human umbilical cord MSCs effectively alleviated DSS-induced weight loss, colon shortening, and intestinal mucosal injury, and reduced clinical disease activity index. The number of neutrophils that infiltrated the intestines of mice treated with human umbilical cord MSCs were decreased and polarised toward the N2 phenotype; at the same time, ERK phosphorylation was inhibited. In vitro experiments showed that addition of the ERK phosphorylation inhibitor, PD98059, down-regulated the expression of N1 neutrophils, while up-regulating that of N2 neutrophils. The colon tissues from patients with IBD were infiltrated with neutrophils. Further, relative to healthy controls, the markers of N1 neutrophils (ICAM-1, FAS, and CCL3) were highly expressed in colon tissues from patients with IBD, whereas the markers of N2 neutrophils (VEGF, CCL2, and CXCR4) were almost undetectable. In conclusion, during alleviation of IBD, human umbilical cord MSCs polarise neutrophils toward the "N2" phenotype by inhibiting activation of ERK signalling.

hucMSCs Attenuate IBD through Releasing miR148b-5p to Inhibit the Expression of 15-lox-1 in Macrophages

Mesenchymal stem cells (MSCs) exert powerful immunosuppression in inflammatory bowel disease (IBD). Macrophages are the dominant inflammatory cells in enteritis regulated via MSCs. However, the roles of macrophages in the process of MSCs attenuating IBD and the mechanisms of MSCs regulating macrophages are largely unknown. In this study, DSS- (dextran sulfate sodium salt-) induced IBD in macrophage-depleted models of CD11b-DTR mice was used to study the relationship between hucMSCs (human umbilical cord mesenchymal stromal cells) and macrophage. Body weights, disease activities, and pathological changes were documented to assess the therapeutic effects of hucMSCs. Furthermore, hucMSCs transfected with miR148b-5p mimics and miR148b-5p inhibitors were cocultured with LPS-induced RAW264.7 cells to investigate the role of miR148b-5p in hucMSC-regulated colitis. The outcome indicated that hucMSCs attenuated the IBD by downregulating 15-lox-1 expression in macrophages. Further findings pointed out that hucMSCs transfected with miR148b-5p mimics could be elevated to promote the tissue repair and inhibit the expression of 15-lox-1 but failed to perform the function of easing enteritis when treated with miR148b-5p inhibitors. In conclusions, we propose that hucMSCs attenuate IBD by releasing miR148b-5p to inhibit the expression of 15-lox-1 in macrophages.

Intestinal Organoids as a Novel Complementary Model to Dissect Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs) include colitis ulcerosa and Crohn's disease, besides the rare microscopic colitis. Both diseases show a long-lasting, relapsing-remitting, or even chronic active course with tremendous impact on quality of life. IBDs frequently cause disability, surgical interventions, and high costs; as in other autoimmune diseases, their prevalent occurrence at an early phase of life raises the burden on health care systems. Unfortunately, our understanding of the pathogenesis is still incomplete and treatment therefore largely focuses on suppressing the resulting excessive inflammation. One obstacle for deciphering the causative processes is the scarcity of models that parallel the development of the disease, since intestinal inflammation is mostly induced artificially; moreover, the intestinal epithelium, which strongly contributes to IBD pathogenesis, is difficult to assess. Recently, the development of intestinal epithelial organoids has overcome many of those problems. Here, we give an overview on the current understanding of the pathogenesis of IBDs with reference to the limitations of previous well-established experimental models. We highlight the advantages and detriments of recent organoid-based experimental setups within the IBD field and suggest possible future applications.

Systematic Exposition of Mesenchymal Stem Cell for Inflammatory Bowel Disease and Its Associated Colorectal Cancer

Mesenchymal stem cells (MSCs) therapy has been applied to a wide range of diseases with excessive immune response, including inflammatory bowel disease (IBD), owing to its powerful immunosuppression and its ability to repair tissue lesions. Different sources of MSCs show different therapeutic properties. Engineering managements are able to enhance the immunomodulation function and the survival of MSCs involved in IBD. The therapeutic mechanism of MSCs in IBD mainly focuses on cell-to-cell contact and paracrine actions. One of the promising therapeutic options for IBD can focus on exosomes of MSCs. MSCs hold promise for the treatment of IBD-associated colorectal cancer because of their tumor-homing function and chronic inflammation inhibition. Encouraging results have been obtained from clinical trials in IBD and potential challenges caused by MSCs therapy are getting solved. This review can assist investigators better to understand the research progress for enhancing the efficacy of MSCs therapy involved in IBD and CAC.

Single cell analysis of Crohn's disease patient-derived small intestinal organoids reveals disease activity-dependent modification of stem cell properties

BACKGROUND

Intestinal stem cells (ISCs) play indispensable roles in the maintenance of homeostasis, and also in the regeneration of the damaged intestinal epithelia. However, whether the inflammatory environment of Crohn's disease (CD) affects properties of resident small intestinal stem cells remain uncertain.

METHODS

CD patient-derived small intestinal organoids were established from enteroscopic biopsy specimens taken from active lesions (aCD-SIO), or from mucosa under remission (rCD-SIO). Expression of ISC-marker genes in those organoids was examined by immunohistochemistry, and also by microfluid-based single-cell multiplex gene expression analysis. The ISC-specific function of organoid cells was evaluated using a single-cell organoid reformation assay.

RESULTS

ISC-marker genes, OLFM4 and SLC12A2, were expressed by an increased number of small intestinal epithelial cells in the active lesion of CD. aCD-SIOs, rCD-SIOs or those of non-IBD controls (NI-SIOs) were successfully established from 9 patients. Immunohistochemistry showed a comparable level of OLFM4 and SLC12A2 expression in all organoids. Single-cell gene expression data of 12 ISC-markers were acquired from a total of 1215 cells. t-distributed stochastic neighbor embedding analysis identified clusters of candidate ISCs, and also revealed a distinct expression pattern of SMOC2 and LGR5 in ISC-cluster classified cells derived from aCD-SIOs. Single-cell organoid reformation assays showed significantly higher reformation efficiency by the cells of the aCD-SIOs compared with that of cells from NI-SIOs.

CONCLUSIONS

aCD-SIOs harbor ISCs with modified marker expression profiles, and also with high organoid reformation ability. Results suggest modification of small intestinal stem cell properties by unidentified factors in the inflammatory environment of CD.

Stem cell transplant in inflammatory bowel disease: a promising modality of treatment for a complicated disease course

Inflammatory bowel disease (IBD) is a complex, relapsing and remitting, disease characterized by an exaggerated immune response in a susceptible host. The symptoms and complications of the disease can be debilitating. Advances in medical treatment in the last decade changed the course of the disease in many patients. Despite the use of novel agents for controlling disease, a proportion of patients' disease courses continue to be either refractory, or become resistant, to available therapeutic options. Stem-cell therapy, with hematopoietic stem cells (HSCs) or mesenchymal stem cells (MSCs), is a promising modality of treatment for severe refractory cases, mainly Crohn's disease (CD) patients. HSCs have the ability to migrate to damaged tissue, which provides them with further properties to differentiate to epithelial or immune-modulatory cells to restore normal mucosal tissue and integrity. MSCs therapy is a promising model for patients with perianal CD due to their immunosuppressive properties, ability to migrate to areas of injury, and demonstration of colonic healing, including fistulizing tracts. The results from ongoing clinical trials will provide a valuable understanding of the future of stem-cell therapy as a treatment option in refractory cases of IBD, a disease whose pathogenesis remains unknown, and is notoriously difficult to treat.

Crosstalk between mesenchymal stem cells and macrophages in inflammatory bowel disease and associated colorectal cancer

Mesenchymal stem cells (MSCs) are attractive seed cells for immunotherapy, tissue engineering and regenerative medicine due to their self-renewal and multidirectional differentiation abilities, diverse immunoregulatory functions and ease of isolation from a wide range of tissues. MSCs exert their immunoregulatory effect on immune cells via cell-to-cell contact and paracrine mechanisms. In turn, MSCs can also be modulated by immune cells. Macrophages are constantly present in the mucosa of the intestinal tract of mammals and play an important role in the development and progression of inflammatory bowel disease (IBD), a chronic and recurrent inflammatory disease of the gastrointestinal tract characterized by idiopathic mucosal inflammation. The increased morbidity and mortality of IBD have made it a disease hard to cure in the clinic. MSCs have emerged as an important tool for IBD therapy due to their abilities to differentiate into enterocyte-like cells and regulate inflammatory cells, especially macrophages. In this review, we discuss the recent advances in the interaction between MSCs and macrophages in diseases, with an emphasis on IBD. We propose that an optimized MSC-based therapy would provide a novel strategy for the treatment of IBD and the prevention of IBD-associated colorectal cancer (CRC).

Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Relieve Inflammatory Bowel Disease in Mice

Exosomes secreted by mesenchymal stem cells (MSCs) have shown repairing effects on several tissue injury diseases. In this study, we aimed to investigate the effects of exosomes released from human umbilical cord mesenchymal stem cells (hucMSCs) on the treatment of dextran sulfate sodium- (DSS-) induced inflammatory bowel disease (IBD) and to explore the underlying mechanism. We found that indocyanine green (ICG) labeled exosomes homed to colon tissues of IBD mice at 12 hours after injection. Exosomes significantly relieved the severity of IBD in mice as hucMSCs. The expression of IL-10 gene was increased while that of TNF-α, IL-1β, IL-6, iNOS, and IL-7 genes was decreased in the colon tissues and spleens of exosomes-treated mice. Furthermore, the infiltration of macrophages into the colon tissues was decreased by exosome treatment in IBD mice. In addition, we provided evidence that in vitro coculture with exosomes inhibited the expression of iNOS and IL-7 in mouse enterocoelia macrophages. Moreover, we found that the expression of IL-7 was higher in the colon tissues of colitis patients than that of healthy controls. Our findings suggest that exosomes from hucMSCs have profound effects on alleviating DSS-induced IBD and may exert their impact through the modulation of IL-7 expression in macrophages.

Mesenchymal Stem Cells and Myeloid Derived Suppressor Cells: Common Traits in Immune Regulation

To protect host against immune-mediated damage, immune responses are tightly regulated. The regulation of immune responses is mediated by various populations of mature immune cells, such as T regulatory cells and B regulatory cells, but also by immature cells of different origins. In this review, we discuss regulatory properties and mechanisms whereby two distinct populations of immature cells, mesenchymal stem cells, and myeloid derived suppressor cells mediate immune regulation, focusing on their similarities, discrepancies, and potential clinical applications.