Mucosally transplanted mesenchymal stem cells stimulate intestinal healing by promoting angiogenesis

Xiaoer-Feire-Qing granules alleviate pyretic pulmonary syndrome induced by Streptococcus pneumoniae in young rats by affecting the lungs and intestines: An in vivo study based on network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine (TCM) Xiaoer-Feire-Qing granules (XEFRQ) has been used to treat pyretic pulmonary syndrome (PPS) in children for many years. The function of the lungs is considered to be closely related to the large intestine in TCM.

PURPOSE

We aimed to investigate the effects of XEFRQ on PPS and the underlying mechanisms via network pharmacology and animal experiments.

METHODS

The TCMSP platform was used to identify the ingredients and potential targets of XEFRQ. The GeneCards, OMIM, and TTD databases were used to predict PPS-associated targets. Cytoscape 3.9.1 was employed to construct the protein-protein interaction network, and target prediction was performed by GO and KEGG analyses. For the animal experiment, a PPS model was constructed by three cycles of nasal drip of Streptococcus pneumoniae (STP; 0.5 mL/kg). The animals were randomly divided into the following four groups according to their weight (n = 10 rats per group): the blank group, the model group, the XEFRQ-L (16.3 g/kg) group, and the XEFRQ-H (56.6 g/kg) group. Rats in the blank group and the model group were given 0.5% CMC-Na by gavage. The general conditions of the rats were observed, and their food-intake, body weight, and body temperature were recorded for 14 days. After the intervention of 14 days, serum was collected to detect inflammatory cytokines (TNF-α, IL-1β, and PGE2) and neurotransmitters (5-HT, SP, and VIP). H&E staining was used to observe the pathological morphology of lung and colon tissue. AQP3 expression was detected by Western blot. In addition, the gut microbiota in cecal content samples were analyzed by 16S rDNA high-throughput sequencing.

RESULTS

Our network analysis revealed that XEFRQ may alleviate PPS injury by affecting the levels of inflammatory cytokines and neurotransmitters and mitigating STP-induced PPS.In vivo validation experiments revealed that XEFRQ improved STP-induced PPS and reduced the expression of inflammatory cytokines and neurotransmitters. Notably, XEFRQ significantly decreased the protein expression levels of AQP3, which was associated with dry stool. Our gut microbiota analysis revealed that the relative abundance of [Eubacterium]_ruminantium_group, Colidextribacter, Romboutsia, and Oscillibacter was decreased, which means XEFRQ exerts therapeutic effects against PPS associated with these bacteria.

CONCLUSION

Our results demonstrate that XEFRQ alleviates PPS by affecting the lungs and intestines, further guiding its clinical application.

Human Adipose-Derived Mesenchymal Stem Cells Colonize and Promote Healing of Leprosy Ulcer by Inducing Neuro-Vascularization

Leprosy ulcer is a chronic and recurrent disease resulting from nerve injury. While existing treatments partially facilitate ulcer healing, they exhibit limited ability to address localized nerve repair, leading to a risk of recurrence. Moreover, there is a dearth of animal models to evaluate the preclinical efficacy and safety of novel therapeutic approaches. Over the years, adipose-derived mesenchymal stem cells have been extensively employed in regenerative medicine as an optimal cell therapy source for fostering skin ulcer healing. They have also demonstrated the capacity to enhance nerve regeneration in in vitro experiments and clinical trials. In this study, we established a NU/NU mouse foot pad leprosy ulcer model, transplanted human adipose-derived stem cells (hADSCs) into leprosy ulcers via local injection, and conducted subsequent follow-up. Our findings revealed that hADSCs persisted in the leprosy ulcer and facilitated the healing process. In this respect, gross observation and histological analysis revealed increased granular formation, collagen synthesis, and re-epithelialization in the local ulcer area. RNA-Seq data revealed that the upregulated differential genes resulting from the transplantation intervention were not only enriched in pathways related to re-epithelialization and collagen synthesis but also contributed to local nerve regeneration. Furthermore, immunofluorescence assays revealed the increased expression of angiogenesis markers-CD31 and VEGFa, cell proliferation markers-Ki67 and TGF-β, and nerve regeneration markers-β3-tubulin, SOX10, NGF, and NT-3. These results underscore the potential of hADSCs in promoting the healing of leprosy ulcers and offer valuable preclinical data for their prospective clinical application.

Two genome-wide interaction loci modify the association of nonsteroidal anti-inflammatory drugs with colorectal cancer

Regular, long-term aspirin use may act synergistically with genetic variants, particularly those in mechanistically relevant pathways, to confer a protective effect on colorectal cancer (CRC) risk. We leveraged pooled data from 52 clinical trial, cohort, and case-control studies that included 30,806 CRC cases and 41,861 controls of European ancestry to conduct a genome-wide interaction scan between regular aspirin/nonsteroidal anti-inflammatory drug (NSAID) use and imputed genetic variants. After adjusting for multiple comparisons, we identified statistically significant interactions between regular aspirin/NSAID use and variants in 6q24.1 (top hit rs72833769), which has evidence of influencing expression of TBC1D7 (a subunit of the TSC1-TSC2 complex, a key regulator of MTOR activity), and variants in 5p13.1 (top hit rs350047), which is associated with expression of PTGER4 (codes a cell surface receptor directly involved in the mode of action of aspirin). Genetic variants with functional impact may modulate the chemopreventive effect of regular aspirin use, and our study identifies putative previously unidentified targets for additional mechanistic interrogation.

Enhancing osteoporosis treatment with engineered mesenchymal stem cell-derived extracellular vesicles: mechanisms and advances

As societal aging intensifies, the incidence of osteoporosis (OP) continually rises. OP is a skeletal disorder characterized by reduced bone mass, deteriorated bone tissue microstructure, and consequently increased bone fragility and fracture susceptibility, typically evaluated using bone mineral density (BMD) and T-score. Not only does OP diminish patients' quality of life, but it also imposes a substantial economic burden on society. Conventional pharmacological treatments yield limited efficacy and severe adverse reactions. In contemporary academic discourse, mesenchymal stem cells (MSCs) derived extracellular vesicles (EVs) have surfaced as auspicious novel therapeutic modalities for OP. EVs can convey information through the cargo they carry and have been demonstrated to be a crucial medium for intercellular communication, playing a significant role in maintaining the homeostasis of the bone microenvironment. Furthermore, various research findings provide evidence that engineered strategies can enhance the therapeutic effects of EVs in OP treatment. While numerous reviews have explored the progress and potential of EVs in treating degenerative bone diseases, research on using EVs to address OP remains in the early stages of basic experimentation. This paper reviews advancements in utilizing MSCs and their derived EVs for OP treatment. It systematically examines the most extensively researched MSC-derived EVs for treating OP, delving not only into the molecular mechanisms of EV-based OP therapy but also conducting a comparative analysis of the strengths and limitations of EVs sourced from various cell origins. Additionally, the paper emphasizes the technical and engineering strategies necessary for leveraging EVs in OP treatment, offering insights and recommendations for future research endeavors.

G protein-coupled receptors: A target for microbial metabolites and a mechanistic link to microbiome-immune-brain interactions

Human-microorganism interactions play a key role in human health. However, the underlying molecular mechanisms remain poorly understood. Small-molecules that offer a functional readout of microbe-microbe-human relationship are of great interest for deeper understanding of the inter-kingdom crosstalk at the molecular level. Recent studies have demonstrated that small-molecules from gut microbiota act as ligands for specific human G protein-coupled receptors (GPCRs) and modulate a range of human physiological functions, offering a mechanistic insight into the microbe-human interaction. To this end, we focused on analysis of bacterial metabolites that are currently recognized to bind to GPCRs and are found to activate the known downstream signaling pathways. We further mapped the distribution of these molecules across the public mass spectrometry-based metabolomics data, to identify the presence of these molecules across body sites and their association with health status. By combining this with RNA-Seq expression and spatial localization of GPCRs from a public human protein atlas database, we inferred the most predominant GPCR-mediated microbial metabolite-human cell interactions regulating gut-immune-brain axis. Furthermore, by evaluating the intestinal absorption properties and blood-brain barrier permeability of the small-molecules we elucidated their molecular interactions with specific human cell receptors, particularly expressed on human intestinal epithelial cells, immune cells and the nervous system that are shown to hold much promise for clinical translational potential. Furthermore, we provide an overview of an open-source resource for simultaneous interrogation of bioactive molecules across the druggable human GPCRome, a useful framework for integration of microbiome and metabolite cataloging with mechanistic studies for an improved understanding of gut microbiota-immune-brain molecular interactions and their potential therapeutic use.

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

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

Wumei Wan attenuates angiogenesis and inflammation by modulating RAGE signaling pathway in IBD: Network pharmacology analysis and experimental evidence

BACKGROUND

Wumei Wan (WMW) has been used to address digestive disorder for centuries in traditional Chinese medicine. Previous studies have demonstrated its anti-colitis efficacy, but the underlying mechanism of its action remains to be further clarified.

PURPOSE

To investigate the underlying mechanisms of WMW in the treatment of chronic ulcerative colitis (UC) through network pharmacology and experimental validation.

METHODS

Traditional Chinese Medicine Systems Pharmacology (TCMSP) platform were used to identify the ingredients and potential targets of WMW. The microarray gene data GSE75214 datasets from GEO database was used to define UC-associated targets. Cytoscape3.7.2 was employed to construct the protein-protein interaction (PPI) network and compounds-disease targets network. GO enrichment analysis and KEGG pathway analysis were performed by R software for functional annotation. UPLC-TOF-MS/MS method was used to quantitatively analyze the active ingredients of WMW. For experimental validation, three cycles of 2% dextran sulfate sodium salt (DSS) were used to construct chronic colitis model. The hub targets and signal pathway were detected by qPCR, ELISA, western blotting , immunohistochemical and immunofluorescence.

RESULTS

Through network analysis, 104 active ingredients were obtained from WMW, and 47 of these ingredients had potential targets for UC. A total of 41 potential targets of WMW and 13 hub targets were identified. KEGG analysis showed that WMW involved in advanced glycation end products-receptor of advanced glycation end products (AGE-RAGE) signaling pathway. Taxifolin, rutaecarpine, kaempferol, quercetin, and luteolin of WMW were the more highly predictive components related to the AGE-RAGE signaling pathway. In vivo validation, WMW improved DSS-induced colitis, reduced the expression of inflammatory cytokines and chemokines. Notably, it significantly decreased the mRNA expression of Spp1, Serpine1, Mmp2, Mmp9, Ptgs2, Nos2, Kdr and Icam1, which were associated with angiogenesis. In addition, we confirmed WMW inhibited RAGE expression and diminished DSS-induced epithelial barrier alterations CONCLUSION: Our results initially demonstrated the effective components and the strong anti-angiogenic activity of WMW in experimental chronic colitis. Sufficient evidence of the satisfactory anti-colitis action of WMW was verified in this study, suggesting its potential as a quite prospective agent for the therapy of UC.

Enforced mesenchymal stem cell tissue colonization counteracts immunopathology

Mesenchymal stem/stromal cells (MSCs) are distributed within all tissues of the body. Though best known for generating connective tissue and bone, these cells also display immunoregulatory properties. A greater understanding of MSC cell biology is urgently needed because culture-expanded MSCs are increasingly being used in treatment of inflammatory conditions, especially life-threatening immune diseases. While studies in vitro provide abundant evidence of their immunomodulatory capacity, it is unknown whether tissue colonization of MSCs is critical to their ability to dampen/counteract evolving immunopathology in vivo. To address this question, we employed a murine model of fulminant immune-mediated inflammation, acute graft-versus-host disease (aGvHD), provoked by donor splenocyte-enriched full MHC-mismatched hematopoietic stem cell transplant. aGvHD induced the expression of E-selectin within lesional endothelial beds, and tissue-specific recruitment of systemically administered host-derived MSCs was achieved by enforced expression of HCELL, a CD44 glycoform that is a potent E-selectin ligand. Compared to mice receiving HCELL⁻ MSCs, recipients of HCELL⁺ MSCs had increased MSC intercalation within aGvHD-affected site(s), decreased leukocyte infiltrates, lower systemic inflammatory cytokine levels, superior tissue preservation, and markedly improved survival. Mechanistic studies reveal that ligation of HCELL/CD44 on the MSC surface markedly potentiates MSC immunomodulatory activity by inducing MSC secretion of a variety of potent immunoregulatory molecules, including IL-10. These findings indicate that MSCs counteract immunopathology in situ, and highlight a role for CD44 engagement in unleashing MSC immunobiologic properties that maintain/establish tissue immunohomeostasis.

Locally injected Mesenchymal Stem Cells optimize angiogenesis by regulating VEGF and CD31 expression in duodenal perforation

Background

Duodenal perforation is considered as one of gastrointestinal emergency with high morbidity and mortality rate. The MSCs have the ability to improve wound healing by releasing several growth factors and anti-inflammatory cytokines to promote the angiogenesis process. This study aimed to investigate the role of MSCs in duodenal perforation wound healing.

Methods

MSCs were isolated from rat umbilical cord and injected into duodenal wound site at doses of 1.5x10 [(Putra et al., 2018) 66 cells for T1 group and 3x10 [(Putra et al., 2018) 66 cells for T2 group. The control group was treated by local injection of normal saline. The VEGF levels were measured by Western blot, while CD31 expression was analyzed using immunohistochemistry staining. All examinations were assessed on days 3 and 7.

Results

Results showed a significant increase in VEGF and CD31 expression on days 3 and 7 (p < 0,05). The VEGF level was significantly decreased on day 7 compared to day 3.

Conclusion

The administration of MSCs improved the angiogenesis process in duodenal perforation by enhancing VEGF and CD31 expression.

•

Duodenal perforation is considered as one of gastrointestinal emergency with high morbidity and mortality rate.

•

The MSCs have the ability to improve wound healing by releasing several growth factors and anti-inflammatory cytokines to promote the angiogenesis process.

•

This study aimed to investigate the role of MSCs in duodenal perforation wound healing.

•

Results showed a significant increase in VEGF and CD31 expression on days 3 and 7.

•

The administration of MSCs improved the angiogenesis process in duodenal perforation.

Transplantation of Wharton's jelly mesenchymal stem cells encapsulated with Hydroactive® Gel promotes diabetic wound antifibrotic healing in type 2 diabetic rats

Diabetic cutaneous ulcers (DCU) are a complication for diabetes patients, mostly occurring in the foot and causing non-healing diabetic foot ulcers. Mesenchymal stem cell (MSC)-based therapy is currently being investigated as a therapeutic avenue for chronic diabetic ulcers. However, poor engraftment, short retention, and low survival still limit the treatment effectiveness. Hydroactive® Gel is a sterile transparent gel made of natural hydrocolloid, which has been widely used for wound management. Whether transplantation of Wharton's jelly mesenchymal stem cells (WJMSCs) encapsulated with Hydroactive® Gel is helpful to diabetic ulcers wound healing remains to be explored. The biocompatibility experiments showed that WJMSCs embedded in Hydroactive® Gel did not influence the cell viability, survival, proliferation, and apoptosis of WJMSCs in vitro. RNA-seq results also implied that Hydroactive® Gel + WJMSCs transplantation activated the "cytokine-cytokine receptor interaction", "mononuclear cell differentiation", "regulation of cell-cell adhesion", and "chemokine receptor activity" to accelerate the inflammatory reaction and epidermis regeneration in diabetic wounds. Histological analysis results demonstrated that Hydroactive® Gel encapsulated WJMSCs transplantation promoted diabetic wound healing and regeneration, indicating improved dermis regeneration, sebaceous gland formation, and type III collagen fiber deposition. Besides, immunohistochemical analysis results showed that Hydroactive® Gel + WJMSCs transplantation also facilitated the transformation of pro-inflammatory M1 macrophages to anti-inflammatory M2 macrophages, cell proliferation, and neovascularization at the wound site. Hydroactive® Gel encapsulation further prolonged the retention time of WJMSCs at the diabetic wound site. Above all, Hydroactive® Gel accelerates WJMSCs-mediated diabetic wound healing by promoting macrophage transformation, facilitating cell proliferation and angiogenesis, and prolonging cell retention time. Our findings may potentially provide a useful therapeutic strategy based on the combination of WJMSCs and biomedical materials for patients with diabetic cutaneous ulcers.

Cytokine Mixtures Mimicking the Local Milieu in Patients with Inflammatory Bowel Disease Impact Phenotype and Function of Mesenchymal Stromal Cells

Locally applied mesenchymal stromal cells (MSCs) have the capacity to promote the healing of perianal fistulas in Crohn’s disease (CD) and are under clinical development for the treatment of proctitis in ulcerative colitis (UC). Despite these clinical advances, the mechanism of action of local MSC therapy in inflammatory bowel disease (IBD) is largely unknown. We hypothesized that the local cytokine environment in IBD patients affects the immunomodulatory properties of MSCs. To evaluate this, 11 cytokines were analyzed in inflamed tissues obtained from CD and UC patients. Based on the identified cytokine profiles 4 distinct cytokine mixtures that mimic various inflammatory IBD environments were established. Next, MSCs were cultured in the presence of either of these 4 cytokine mixtures after which the expression of immunomodulatory and tissue regenerative molecules and the capacity of MSCs to modulate T-cell proliferation and dendritic cell (DC) differentiation were assessed. Our data show that MSCs respond, in a cytokine-specific manner, by upregulation of immunomodulatory and tissue regenerative molecules, including cyclooxygenase-2, indoleamine 2,3-dioxygenase, and transforming growth factor-β1. Functional studies indicate that MSCs exposed to a cytokine profile mimicking one of the 2 UC cytokine milieus were less effective in inhibition of DC differentiation. In conclusion, our data indicate that cytokine mixes mimicking the local cytokine milieus of inflamed UC colonic or CD fistulas tissues can differentially affect the immunomodulatory and tissue regenerative characteristics of MSCs. These data support the hypothesis that the local intestinal cytokine milieu serves as a critical factor in the efficacy of local MSC treatment.

Reverse translation approach generates a signature of penetrating fibrosis in Crohn's disease that is associated with anti-TNF response

OBJECTIVE

Fibrosis is a common feature of Crohn's disease (CD) which can involve the mesenteric fat. However, the molecular signature of this process remains unclear. Our goal was to define the transcriptional signature of mesenteric fibrosis in CD subjects and to model mesenteric fibrosis in mice to improve our understanding of CD pathogenesis.

DESIGN

We performed histological and transcriptional analysis of fibrosis in CD samples. We modelled a CD-like fibrosis phenotype by performing repeated colonic biopsies in mice and analysed the model by histology, type I collagen-targeted positron emission tomography (PET) and global gene expression. We generated a gene set list of essential features of mesenteric fibrosis and compared it to mucosal biopsy datasets from inflammatory bowel disease patients to identify a refined gene set that correlated with clinical outcomes.

RESULTS

Mesenteric fibrosis in CD was interconnected to areas of fibrosis in all layers of the intestine, defined as penetrating fibrosis. We found a transcriptional signature of differentially expressed genes enriched in areas of the mesenteric fat of CD subjects with high levels of fibrosis. Mice subjected to repeated colonic biopsies showed penetrating fibrosis as shown by histology, PET imaging and transcriptional analysis. Finally, we composed a composite 24-gene set list that was linked to inflammatory fibroblasts and correlated with treatment response.

CONCLUSION

We linked histopathological and molecular features of CD penetrating fibrosis to a mouse model of repeated biopsy injuries. This experimental system provides an innovative approach for functional investigations of underlying profibrotic mechanisms and therapeutic concepts in CD.

Colonic healing requires Wnt produced by epithelium as well as Tagln+ and Acta2+ stromal cells

Although Wnt signaling is clearly important for the intestinal epithelial homeostasis, the relevance of various sources of Wnt ligands themselves remains incompletely understood. Blocking the release of Wnt in distinct stromal cell types suggests obligatory functions of several stromal cell sources and yields different observations. The physiological contribution of epithelial Wnt to tissue homeostasis remains unclear. We show here that blocking epithelial Wnts affects colonic Reg4+ epithelial cell differentiation and impairs colonic epithelial regeneration after injury in mice. Single-cell RNA analysis of intestinal stroma showed that the majority of Wnt-producing cells were contained in transgelin (Tagln+) and smooth muscle actin α2 (Acta2+) expressing populations. We genetically attenuated Wnt production from these stromal cells using Tagln-Cre and Acta2-CreER drivers, and found that blockage of Wnt release from either epithelium or Tagln+ and Acta2+ stromal cells impaired colonic epithelial healing after chemical-induced injury. Aggregated blockage of Wnt release from both epithelium and Tagln+ or Acta2+ stromal cells drastically diminished epithelial repair, increasing morbidity and mortality. These results from two uncharacterized stromal populations suggested that colonic recovery from colitis-like injury depends on multiple Wnt-producing sources.

Cells and mediators of inflammation as effectors of epithelial repair in the inflamed intestine

Mucosal and histological healing have become the gold standards for assessing the efficacy of therapy in patients living with inflammatory bowel diseases (IBD). Despite these being the accepted goals in therapy, the mechanisms that underlie the healing of the mucosa after an inflammatory insult are not well understood, and many patients fail to meet this therapeutic endpoint. Here we review the emerging evidence that mediators (e.g., prostaglandins, cytokines, proteases, reactive oxygen, and nitrogen species) and innate immune cells (e.g., neutrophils and monocytes/macrophages), that are involved in the initiation of the inflammatory response, are also key players in the mechanisms underlying mucosal healing to resolve chronic inflammation in the colon. The dual function mediators comprise an inflammation/repair program that returns damaged tissue to homeostasis. Understanding details of the dual mechanisms of these mediators and cells may provide the basis for the development of drugs that can help to stimulate epithelial repair in patients affected by IBD.

Iontophoresis of treprostinil promotes wound healing in a murine model of scleroderma-related ulcers

OBJECTIVE

Systemic Sclerosis (SSc) is a rare, chronic disease characterized by fibrosis, vascular alterations and digital ulcerations. Few drugs have shown efficacy to enhance wound healing of existing SSc-related ulcers. Local delivery of treprostinil, a prostacyclin analogue, may improve wound healing. The present work aimed first at developing a mouse model of SSc-related ulcerations and second at assessing the effect of iontophoresis of treprostinil on wound healing.

METHODS

We used two murine models of SSc: chemically-induced with HOCl, and Urokinase-type plasminogen activator receptor (uPAR)-deficient. Excisional wounding was performed on the dorsal midline with a biopsy punch. Animals were randomized into three groups: treated with electrostimulation alone, with treprostinil iontophoresis, or untreated. We assessed wound healing over time, as well as skin microvascular reactivity, inflammation, microvessel density, and collagen distribution, before wounding and after re-epithelialization.

RESULTS

uPAR-/- mice, but not HOCl-treated mice, showed impaired wound healing and decreased microvascular reactivity compared with their controls. Treprostinil iontophoresis improved wound healing and microvascular density and decreased inflammation in uPAR-/- mice, while electro-stimulation did not. However, treprostinil had no effect on microvascular reactivity and collagen distribution.

CONCLUSION

This study suggests that excisional wounds in uPAR-/- mice are a relevant model of SSc-related ulcers. In addition, treprostinil iontophoresis enhances wound healing in this model. Further work in now needed to show whether this effect translates in humans.

Wharton's jelly mesenchymal stem cells embedded in PF-127 hydrogel plus sodium ascorbyl phosphate combination promote diabetic wound healing in type 2 diabetic rat

Background

Diabetic cutaneous ulcers (DCU) are a complication of diabetes with diabetic foot ulcers being the most common, and the wounds are difficult to heal, increasing the risk of bacterial infection. Cell-based therapy utilizing mesenchymal stem cells (MSCs) is currently being investigated as a therapeutic avenue for both chronic diabetic ulcers and severe burns. Wharton’s jelly mesenchymal stem cell (WJMSC) with PF-127 hydrogel and sodium ascorbyl phosphate (SAP) improved skin wound healing in mice. Whether this combination strategy is helpful to diabetic ulcers wound healing remains to be explored.

Methods

Firstly, the WJMSCs embedded in PF-127 and SAP combination were transplanted onto excisional cutaneous wound bed in type 2 diabetic Sprague Dawley (SD) rats. Two weeks after transplantation, the skin tissue was collected for histological and immunohistochemical analysis. Further, overexpressing-EGFP WJMSCs were performed to investigate cell engraftment in the diabetic cutaneous ulcer. The apoptosis of WJMSCs which encapsulated with combination of PF-127 and SAP was detected by TUNEL fluorescence assay and RT-PCR in vitro. And the mitochondrial damage induced by oxidative stress assessed by MitoTracker and CMH2DCFDA fluorescence assay.

Results

In diabetic cutaneous wound rat model, PF-127 plus SAP-encapsulated WJMSCs transplantation promoted diabetic wound healing, indicating improving dermis regeneration and collagen deposition. In diabetic wound healing, less pro-inflammatory M1 macrophages, more anti-inflammatory M2 tissue-healing macrophages, and neovascularization were observed in PF-127 + SAP + WJMSCs group compared with other groups. SAP supplementation alleviated the apoptosis ratio of WJMSCs embedded in the PF-127 in vitro and promoted cell survival in vivo.

Conclusion

PF-127 plus SAP combination facilitates WJMSCs-mediated diabetic wound healing in rat through promoting cell survival, the macrophage transformation, and angiogenesis. Our findings may potentially provide a helpful therapeutic strategy for patients with diabetic cutaneous ulcer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02626-w.

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.

Wogonin Strengthens the Therapeutic Effects of Mesenchymal Stem Cells in DSS-Induced Colitis via Promoting IL-10 Production

Inflammatory bowel diseases (IBD) are prevalent and debilitating diseases; their clinical remedy is desperately unmet. Mesenchymal stem cells (MSCs) are pluripotent stem cells with multiple immunomodulatory effects, which are attributed to their efficacy in the IBD rodent model. Optimization of MSC regimes in IBD is a crucial step for their further clinical application. Wogonin is a flavonoid-like compound, which showed extensive immunomodulatory and adjuvant effects. This research is aimed at investigating whether and how Wogonin boosted the therapeutic efficiency of MSCs on DSS-induced colitis. Our results showed that the MSC treatment with Wogonin significantly alleviated the intestinal inflammation in IBD mice by increased IL-10 expression. In vitro experiments, Wogonin obviously raised the IL-10 production and ROS levels of MSCs in a dose-dependent manner. Meanwhile, western blot data suggested Wogonin improves the IL-10 production by inducing transcript factor HIF-1α expression via AKT/GSK3β signal pathway. Finally, the favorable effects of Wogonin on MSCs were confirmed by IL-10 blockade experiment in vivo. Together, our results suggested that Wogonin significantly increased the IL-10 production and enhanced the therapeutic effects of MSCs in DSS-induced colitis. This work suggested Wogonin as a novel optimal strategy for MSC clinical application.

Gli1+ Cells Couple with Type H Vessels and Are Required for Type H Vessel Formation

Mesenchymal stem/stromal cells (MSCs) reside in the perivascular niche and modulate tissue/organ homeostasis; however, little is known about whether and how their localization and function are linked. Particularly, whether specific MSC subsets couple with and regulate specialized vessel subtypes is unclear. Here, we show that Gli1⁺ cells, which are a subpopulation of MSCs couple with and regulate a specialized form of vasculature. The specific capillaries, i.e., CD31^hiEMCN^hi type H vessels, are the preferable vascular subtype which Gli1⁺ cells are adjacent to in bone. Gli1⁺ cells are further identified to be phenotypically coupled with type H endothelium during bone growth and defect healing. Importantly, Gli1⁺ cell ablation inhibits type H vessel formation associated with suppressed bone generation and regeneration. Mechanistically, Gli1⁺ cells initiate angiogenesis through Gli and HIF-1α signaling. These findings suggest a morphological and functional framework of Gli1⁺ cells modulating coupled type H vasculature for tissue homeostasis and regenerative repair.

Adipose-derived mesenchymal stem cells inhibit cell proliferation and migration and suppress extracellular matrix synthesis in hypertrophic-scar and keloid fibroblasts

Pathological scars occur during skin wound healing, and the use of adipose-derived stem cells (ADSCs) is one of the various treatments. The present study aimed to investigate the in vitro effects of ADSCs on the biological properties of hypertrophic scar fibroblasts (HSFs) and keloid fibroblasts (KFs), such as proliferation, migration, and the synthesis of extracellular matrix proteins. Transwell chambers were used to establish a co-culture system of ADSCs with normal skin fibroblasts (NFs), HSFs or KFs. The effect of ADSCs on the proliferation of fibroblasts was evaluated by CCK8 measurement, while the migration ability of fibroblasts was assessed using cell scratch assay. The expression of extracellular matrix proteins was measured by immunoblotting. Co-culture of NFs with ADSCs did not affect cell proliferation and migration, nor the expression of extracellular matrix proteins [collagen-I, collagen-III, fibronectin (FN) and α-smooth muscle actin (α-SMA)] in NFs. However, as with the inhibitor SB431542, ADSCs significantly inhibited cell proliferation and migration and the expression of extracellular matrix proteins (collagen-I, collagen-III, FN and α-SMA), but also suppressed the protein expression of transforming growth factor β1 (TGF-β1), phosphorylated (p-) mothers against decapentaplegic homolog (Smad) 2, p-Smad3 and Smad7 in HSFs and KFs. The results show that ADSCs inhibited cell proliferation and migration and the expression of extracellular matrix proteins in HSCs and KFs in vitro, possibly through inhibition of the TGF-β1/Smad pathway.

Intestinal Morphogenesis in Development, Regeneration, and Disease: The Potential Utility of Intestinal Organoids for Studying Compartmentalization of the Crypt-Villus Structure

The morphology and structure of the intestinal epithelium are rearranged dynamically during development, tissue regeneration, and disease progression. The most important characteristic of intestinal epithelial morphogenesis is the repetitive compartmentalized structures of crypt-villus units, which are crucial for maintaining intestinal homeostasis and functions. Abnormal structures are known to be closely associated with disease development and progression. Therefore, understanding how intestinal crypt-villus structures are formed and grown is essential for elucidating the physiological and pathophysiological roles of the intestinal epithelium. However, a critical knowledge gap in understanding the compartmentalization of the crypt-villus axis remains when using animal models, due to obvious inter-species differences and difficulty in real-time monitoring. Recently, emerging technologies such as organoid culture, lineage tracing, and single cell sequencing have enabled the assessment of the intrinsic mechanisms of intestinal epithelial morphogenesis. In this review, we discuss the latest research on the regulatory factors and signaling pathways that play a central role in the formation, maintenance, and regeneration of crypt-villus structures in the intestinal epithelium. Furthermore, we discuss how these factors and pathways play a role in development, tissue regeneration, and disease. We further explore how the current technology of three-dimensional intestinal organoids has contributed to the understanding of crypt-villus compartmentalization, highlighting new findings related to the self-organizing-process-driven initiation and propagation of crypt-villus structures. We also discuss intestinal diseases featuring abnormalities of the crypt-villus structure to provide insights for the development of novel therapeutic strategies targeting intestinal morphogenesis and crypt-villus formation.

Angiogenic effects of low molecular weight organic acids present in fulvic acids of different sources

Fulvic acid (FA) is a natural mineral medicine with a long medical history in folk. However, the active chemicals of FA remain unknown due to its diversity of sources and the complexity of compositions, which have become a bottleneck in quality control and medicinal development. Based on the traditional effect on angiogenesis, FAs from eight different coal sources were prepared and their active fractions were investigated by the CAM model, resulting that most of acetonitrile dissolved parts of these FAs (DFAs) produced angiogenesis effects. Through chemical analysis on DFAs by GC-FID/MS, six shared organic acids with low molecular weights were identified and quantified, which showed the promoting effects on capillary areas, VEGF, b-FGF, and Ang-1 at different degrees. The PCA analysis showed that the five shared organic acids with high recognition are the active chemicals in different sources of FAs which may be responsible for the angiogenesis effects.

Aspirin in the Prevention of Colorectal Neoplasia

High-quality evidence indicates that regular use of aspirin is effective in reducing the risk for precancerous colorectal neoplasia and colorectal cancer (CRC). This has led to US and international guidelines recommending aspirin for the primary prevention of CRC in specific populations. In this review, we summarize key questions that require addressing prior to broader adoption of aspirin-based chemoprevention, review recent evidence related to the benefits and harms of aspirin use among specific populations, and offer a rationale for precision prevention approaches. We specifically consider the mechanistic implications of evidence showing differences in aspirin's effects according to age, the potential role of modifiable mechanistic biomarkers for personalizing prevention, and emerging evidence that the gut microbiota may offer novel aspirin-associated preventive targets to reduce high-risk neoplasia.

Stromal Cells in the Pathogenesis of Inflammatory Bowel Disease

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

Proangiogenic Hypoxia-Mimicking Agents Attenuate Osteogenic Potential of Adipose Stem/Stromal Cells

BACKGROUND

Insufficient vascularization hampers bone tissue engineering strategies for reconstructing large bone defects. Delivery of prolyl-hydroxylase inhibitors (PHIs) is an interesting approach to upregulate vascular endothelial growth factor (VEGF) by mimicking hypoxic stabilization of hypoxia-inducible factor-1alpha (HIF-1α). This study assessed two PHIs: dimethyloxalylglycine (DMOG) and baicalein for their effects on human adipose tissue-derived mesenchymal stem/stromal cells (AT-MSCs).

METHODS

Isolated AT-MSCs were characterized and treated with PHIs to assess the cellular proliferation response. Immunostaining and western-blots served to verify the HIF-1α stabilization response. The optimized concentrations for long-term treatment were tested for their effects on the cell cycle, apoptosis, cytokine secretion, and osteogenic differentiation of AT-MSCs. Gene expression levels were evaluated for alkaline phosphatase (ALPL), bone morphogenetic protein 2 (BMP2), runt-related transcription factor 2 (RUNX2), vascular endothelial growth factor A (VEGFA), secreted phosphoprotein 1 (SPP1), and collagen type I alpha 1 (COL1A1). In addition, stemness-related genes Kruppel-like factor 4 (KLF4), Nanog homeobox (NANOG), and octamer-binding transcription factor 4 (OCT4) were assessed.

RESULTS

PHIs stabilized HIF-1α in a dose-dependent manner and showed evident dose- and time dependent antiproliferative effects. With doses maintaining proliferation, DMOG and baicalein diminished the effect of osteogenic induction on the expression of RUNX2, ALPL, and COL1A1, and suppressed the formation of mineralized matrix. Suppressed osteogenic response of AT-MSCs was accompanied by an upregulation of stemness-related genes.

CONCLUSION

PHIs significantly reduced the osteogenic differentiation of AT-MSCs and rather upregulated stemness-related genes. PHIs proangiogenic potential should be weighed against their longterm direct inhibitory effects on the osteogenic differentiation of AT-MSCs.

PF-127 hydrogel plus sodium ascorbyl phosphate improves Wharton's jelly mesenchymal stem cell-mediated skin wound healing in mice

Background

Factors such as poor engraftment, retention, and survival of the transplanted stem cells are deemed to limit their therapeutic efficacy for wound regeneration. Hence, it is necessary to explore these issues in order to resolve them. In this study, we aim to investigate the role of Pluronic F-127 (PF-127) hydrogel plus antioxidant sodium ascorbyl phosphate (SAP) in enhancing Wharton’s jelly mesenchymal stem cell (WJMSC)-mediated effectiveness on full-thickness skin wound healing in mice.

Methods

First, the cytotoxicity of PF-127 and the biological effect of SAP on the survival of WJMSCs were tested in vitro using cell viability and proliferation assays. Next, a cell suspension containing WJMSCs, PF-127, and SAP was topically administered onto an 8-mm diameter excisional full-thickness wound bed. Eight days after transplantation, the mice were sacrificed and the skin tissue was excised for histological and immunohistochemical analysis. Finally, in vivo distribution of transplanted WJMSCs was traced to investigate cell engraftment and the potential therapeutic mechanism.

Results

PF-127 was found to be cytotoxic to WJMSCs while SAP significantly improved the survival of PF-127-embedded WJMSCs. When this combination was topically transplanted onto the wound bed, wound healing was facilitated and dermis regeneration was achieved on the 8th day after surgery, as evidenced by an increase in dermal thickness, newly developed hair follicles, and collagen fiber deposition accompanied by a reduction in scar width. Further, immunohistochemical analysis demonstrated a higher number of anti-inflammatory M2 macrophages, proliferating cells, and newly formed blood vessels in the WJMSCs/PF-127/SAP group relative to all other groups. In addition, in vivo tracking results revealed a highly enhanced engraftment of WJMSCs accumulated in the dermis in the WJMSCs/PF-127/SAP group.

Conclusions

SAP significantly improves the survival of WJMSCs in PF-127 encapsulation. Further, PF-127 plus SAP is an effective combination that enhances WJMSC engraftment in the dermis, which then promotes full-thickness wound healing through potential M2 macrophage formation and angiogenesis.

Promoters to Study Vascular Smooth Muscle

Smooth muscle cells (SMCs) are a critical component of blood vessel walls that provide structural support, regulate vascular tone, and allow for vascular remodeling. These cells also exhibit a remarkable plasticity that contributes to vascular growth and repair but also to cardiovascular pathologies, including atherosclerosis, intimal hyperplasia and restenosis, aneurysm, and transplant vasculopathy. Mouse models have been an important tool for the study of SMC functions. The development of smooth muscle-expressing Cre-driver lines has allowed for exciting discoveries, including recent advances revealing the diversity of phenotypes derived from mature SMC transdifferentiation in vivo using inducible CreER ^T2 lines. We review SMC-targeting Cre lines driven by the Myh11, Tagln, and Acta2 promoters, including important technical considerations associated with these models. Limitations that can complicate study of the vasculature include expression in visceral SMCs leading to confounding phenotypes, and expression in multiple nonsmooth muscle cell types, such as Acta2-Cre expression in myofibroblasts. Notably, the frequently employed Tagln/ SM22α- Cre driver expresses in the embryonic heart but can also confer expression in nonmuscular cells including perivascular adipocytes and their precursors, myeloid cells, and platelets, with important implications for interpretation of cardiovascular phenotypes. With new Cre-driver lines under development and the increasing use of fate mapping methods, we are entering an exciting new era in SMC research.

Cardio-renal Exosomes in Myocardial Infarction Serum Regulate Proangiogenic Paracrine Signaling in Adipose Mesenchymal Stem Cells

Rationale: Mesenchymal stem cells (MSCs) play important roles in tissue repair and regeneration. However, the molecular mechanisms underlying MSCs activation remain largely unknown, thus hindering their clinical translation. Exosomes are small vesicles that act as intercellular messengers, and their potential for stem cell activation in pathological conditions has not been fully characterized yet. Here, we aim to investigate whether serum exosomes are involved in the remote activation of MSCs after myocardial infarction (MI).

Methods: We established MI mouse model by ligating the left anterior descending branch of the coronary artery. Afterwards, serum exosomes were isolated from control (Con Exo) and MI mice (MI Exo) by differential centrifugation. Exosomes were characterized through transmission electron microscopy and nanoparticle tracking analysis. The cell proliferation rate was evaluated by CCK-8 and EdU incorporation assays. Exosomal miRNA and protein levels were assessed using qRT-PCR and western blotting, respectively. VEGF levels in the supernatant and serum were quantified by ELISA. Matrigel plug and tube formation assays were used to evaluate angiogenesis. To explore miR-1956 roles, overexpression and knock-down experiments were performed using mimic and inhibitor, respectively. Finally, miR-1956 target genes were confirmed using the luciferase reporter assay.

Results: Both types of exosomes exhibited typical characteristics and could be internalized by adipose-derived MSCs (ADMSCs). MI Exo enhanced ADMSCs proliferation through the activation of ERK1/2. Gain- and loss-of-function studies allowed the validation of miR-1956 (enriched in MI Exo) as the functional messenger that stimulates ADMSCs-mediated angiogenesis and paracrine VEGF signaling, by downregulating Notch-1. Finally, we found that the ischemic myocardium and kidney may be the main sources that release serum exosomes after MI.

Conclusions: Cardio-renal exosomes deliver miR-1956 and activate paracrine proangiogenic VEGF signaling in ADMSCs after MI; this process also involves Notch-1, which functions as the core mediator.

Stem cell-based therapy for inflammatory bowel disease

Inflammatory bowel disease (IBD) is an idiopathic, multi-etiological disease characterized by inflammation and mucosal destruction of the gastrointestinal tract. Despite the remarkable advance in immunomodulating therapies, there still remains a certain population of patients who are refractory to conventional as well as biologic therapies and fail to achieve mucosal healing. To improve the prognosis of those patients, at least 2 types of stem cells have been tested for their potential therapeutic use. Transplantation of hematopoietic stem cells or mesenchymal stem cells have been tested in several clinical studies, but their beneficial effect still remains controversial. In this review, we would like to overview the recent clinical challenges of stem cell-based therapies in IBD and also introduce our new therapeutic plan of intestinal stem cell transplantation for IBD, based on our ex vivo intestinal organoid culture technique.

Effect of cell source and osteoblast differentiation on gene expression profiles of mesenchymal stem cells derived from bone marrow or adipose tissue

Mesenchymal stem cells (MSCs) have been used in therapies for bone tissue healing. The aim of this study was to investigate the effect of cell source and osteoblast differentiation on gene expression profiles of MSCs from bone marrow (BM-MSCs) or adipose tissue (AT-MSCs) to contribute for selecting a suitable cell population to be used in cell-based strategies for bone regeneration. BM-MSCs and AT-MSCs were cultured in growth medium to keep MSCs characteristics or in osteogenic medium to induce osteoblast differentiation (BM-OBs and AT-OBs). The transcriptomic analysis was performed by microarray covering the entire rat functional genome. It was observed that cells from bone marrow presented higher expression of genes related to osteogenesis, whereas cells from adipose tissue showed a higher expression of genes related to angiogenesis and adipocyte differentiation, irrespective of cell differentiation. By comparing cells from the same source, MSCs from both sources exhibited higher expression of genes involved in angiogenesis, osteoblast differentiation, and bone morphogenesis than osteoblasts. The clustering analysis showed that AT-OBs exhibited a gene expression profile closer to MSCs from both sources than BM-OBs, suggesting that BM-OBs were in a more advanced stage of differentiation. In conclusion, our results suggest that in cell-based therapies for bone regeneration AT-MSCs could be considered for angiogenic purposes, whereas BM-MSCs and osteoblasts differentiated from either source could be better for osteogenic approaches.

Lactobacillus rhamnosus GG protects the intestinal epithelium from radiation injury through release of lipoteichoic acid, macrophage activation and the migration of mesenchymal stem cells

OBJECTIVE

Lactobacillus rhamnosus GG (LGG), a probiotic, given by gavage is radioprotective of the mouse intestine. LGG-induced radioprotection is toll-like receptor 2 (TLR2) and cyclooxygenase-2 (COX-2)-dependent and is associated with the migration of COX-2+mesenchymal stem cells (MSCs) from the lamina propria of the villus to the lamina propria near the crypt epithelial stem cells. Our goals were to define the mechanism of LGG radioprotection including identification of the TLR2 agonist, and the mechanism of the MSC migration and to determine the safety and efficacy of this approach in models relevant to clinical radiation therapy.

DESIGN

Intestinal radioprotection was modelled in vitro with cell lines and enteroids as well as in vivo by assaying clinical outcomes and crypt survival. Fractionated abdominal and single dose radiation were used along with syngeneic CT26 colon tumour grafts to assess tumour radioprotection.

RESULTS

LGG with a mutation in the processing of lipoteichoic acid (LTA), a TLR2 agonist, was not radioprotective, while LTA agonist and native LGG were. An agonist of CXCR4 blocked LGG-induced MSC migration and LGG-induced radioprotection. LGG given by gavage induced expression of CXCL12, a CXCR4 agonist, in pericryptal macrophages and depletion of macrophages by clodronate liposomes blocked LGG-induced MSC migration and radioprotection. LTA effectively protected the normal intestinal crypt, but not tumours in fractionated radiation regimens.

CONCLUSIONS

LGG acts as a 'time-release capsule' releasing radioprotective LTA. LTA then primes the epithelial stem cell niche to protect epithelial stem cells by triggering a multicellular, adaptive immune signalling cascade involving macrophages and PGE2 secreting MSCs.

TRIAL REGISTRATION NUMBER

NCT01790035; Pre-results.

Challenges in IBD Research: Preclinical Human IBD Mechanisms

Preclinical human IBD mechanisms is part of five focus areas of the Challenges in IBD research document, which also include environmental triggers, novel technologies, precision medicine and pragmatic clinical research. The Challenges in IBD research document provides a comprehensive overview of current gaps in inflammatory bowel diseases (IBD) research and delivers actionable approaches to address them. It is the result of a multidisciplinary input from scientists, clinicians, patients, and funders, and represents a valuable resource for patient centric research prioritization. In particular, the preclinical human IBD mechanisms manuscript is focused on highlighting the main research gaps in the pathophysiological understanding of human IBD. These research gap areas include: 1) triggers of immune responses; 2) intestinal epithelial homeostasis and wound repair; 3) age-specific pathophysiology; 4) disease complications; 5) heterogeneous response to treatments; and 6) determination of disease location. As an approach to address these research gaps, the prioritization of reverse translation studies is proposed in which clinical observations are the foundation for experimental IBD research in the lab, and for the identification of new therapeutic targets and biomarkers. The use of human samples in validating basic research findings and development of precision medicine solutions is also proposed. This prioritization aims to put emphasis on relevant biochemical pathways and humanized in vitro and in vivo models that extrapolate meaningfully to human IBD, to eventually yield first-in-class and effective therapies.

Cancer-associated fibroblasts in gastrointestinal cancer

The tumour microenvironment, also termed the tumour stroma or tumour mesenchyme, includes fibroblasts, immune cells, blood vessels and the extracellular matrix and substantially influences the initiation, growth and dissemination of gastrointestinal cancer. Cancer-associated fibroblasts (CAFs) are one of the critical components of the tumour mesenchyme and not only provide physical support for epithelial cells but also are key functional regulators in cancer, promoting and retarding tumorigenesis in a context-dependent manner. In this Review, we outline the emerging understanding of gastrointestinal CAFs with a particular emphasis on their origin and heterogeneity, as well as their function in cancer cell proliferation, tumour immunity, angiogenesis, extracellular matrix remodelling and drug resistance. Moreover, we discuss the clinical implications of CAFs as biomarkers and potential targets for prevention and treatment of patients with gastrointestinal cancer.

Contribution of Wound-Associated Cells and Mediators in Orchestrating Gastrointestinal Mucosal Wound Repair

The gastrointestinal mucosa, structurally formed by the epithelium and lamina propria, serves as a selective barrier that separates luminal contents from the underlying tissues. Gastrointestinal mucosal wound repair is orchestrated by a series of spatial and temporal events that involve the epithelium, recruited immune cells, resident stromal cells, and the microbiota present in the wound bed. Upon injury, repair of the gastrointestinal barrier is mediated by collective migration, proliferation, and subsequent differentiation of epithelial cells. Epithelial repair is intimately regulated by a number of wound-associated cells that include immune cells and stromal cells in addition to mediators released by luminal microbiota. The highly regulated interaction of these cell types is perturbed in chronic inflammatory diseases that are associated with impaired wound healing. An improved understanding of prorepair mechanisms in the gastrointestinal mucosa will aid in the development of novel therapeutics that promote mucosal healing and reestablish the critical epithelial barrier function.

Colonoscopic-Guided Pinch Biopsies in Mice as a Useful Model for Evaluating the Roles of Host and Luminal Factors in Colonic Inflammation

Colonic inflammation, a hallmark of inflammatory bowel disease, can be influenced by host intrinsic and extrinsic factors. There continues to be a need for models of colonic inflammation that can both provide insights into disease pathogenesis and be used to investigate potential therapies. Herein, we tested the utility of colonoscopic-guided pinch biopsies in mice for studying colonic inflammation and its treatment. Gene expression profiling of colonic wound beds after injury showed marked changes, including increased expression of genes important for the inflammatory response. Interestingly, many of these gene expression changes mimicked those alterations found in inflammatory bowel disease patients. Biopsy-induced inflammation was associated with increases in neutrophils, macrophages, and natural killer cells. Injury also led to elevated levels of sphingosine-1-phosphate (S1P), a bioactive lipid that is an important mediator of inflammation mainly through its receptor, S1P₁. Genetic deletion of S1P₁ in the endothelium did not alter the inflammatory response but led to increased colonic bleeding. Bacteria invaded into the wound beds, raising the possibility that microbes contributed to the observed changes in mucosal gene expression. In support of this, reducing bacterial abundance markedly attenuated the inflammatory response to wounding. Taken together, this study demonstrates the utility of the pinch biopsy model of colonic injury to elucidate the molecular underpinnings of colonic inflammation and its treatment.

Endoscopic Administration of Mesenchymal Stromal Cells Reduces Inflammation in Experimental Colitis

BACKGROUND

Mesenchymal stromal cells (MSCs) are a potential therapeutic modality in inflammatory bowel diseases (IBDs) because of their immunomodulatory and regenerative properties. However, when injected systemically, only a small portion of the cells, if any, reach the inflamed colon. In this study, we assessed whether endoscopic injections of MSCs into the intestinal wall of the inflamed colon affect the course of experimental colitis. Furthermore, we investigated if injection of aggregated MSCs in spheroids could enhance their therapeutic ability.

METHODS

Expression levels of in vivo MSC aggregates and in vitro MSC spheroids were compared with monolayer cultured MSCs for both anti-inflammatory and pro-regenerative factors. Subsequently, MSCs and MSC spheroids were injected endoscopically in mice with established dextran sulfate sodium (DSS)-induced colitis.

RESULTS

Endoscopically injected MSCs and MSC spheroids both alleviated DSS-induced colitis. Furthermore, both in vivo and in vitro MSC spheroids showed increased expression of factors important for immunomodulation and tissue repair, compared with monolayer cultured MSCs. Despite differential expression of these factors, MSC spheroids showed similar clinical efficacy in vivo as single-cell suspension MSCs. Analysis of serum samples and colon homogenates showed that local MSC therapy resulted in increased levels of interferon-γ, indoleamine 2,3-dixoygenase, and interleukin-10.

CONCLUSIONS

Endoscopic injections of MSCs and MSC spheroids in the inflamed colon attenuate DSS-induced colitis. Our data show that endoscopic injection can be a feasible and effective novel application route for MSC therapy in patients with luminal IBD.

Hierarchically porous composite microparticles from microfluidics for controllable drug delivery

Abdominal wall defect repair remains a major clinical need, and a particle-based controllable drug delivery system offers a solution to this problem. Here, we present a new type of hierarchically porous microparticles (HPMs) composed of poly(lactic-co-glycolic acid) (PLGA) and hollow mesoporous silica nanoparticles (HMSNs) for the delivery. The HPMs are generated by drying microfluidic emulsion templates of HMSNs-dispersed PLGA solution. The resultant HPMs have tailorable porous structures, that provide a three-hierarchy architecture for the controlled release of actives. The first hierarchy is formed for controlling the drug release via physical absorption as a result of the presence of the HMSNs in the HPMs. The second hierarchy channels with small pores scattered throughout the surface of the HPMs are formed during evaporation of the solvent. The third hierarchy with openings on the surface of the HPMs is formed as a result of the inner droplets leaking out of the double emulsion templates during the PLGA solidification. Thus, by manipulating the flow of solutions during the microfluidic emulsification, the porous structures of HPMs can be easily and precisely adjusted, and the loaded drugs are delivered at the required rate. These features of the HPMs make them ideal for repairing abdominal wall defects.

Endoscopic submucosal injection of adipose-derived mesenchymal stem cells ameliorates TNBS-induced colitis in rats and prevents stenosis

Background

Mesenchymal stem cells have potential applications in inflammatory bowel disease due to their immunomodulatory properties. Our aim was to evaluate the feasibility, safety and efficacy of endoscopic administration of adipose-derived mesenchymal stem cells (ASCs) in a colitis model in rats.

Methods

Colitis was induced in rats by rectal trinitrobenzenesulfonic acid (TNBS). After 24 h ASCs (10⁷ cells) or saline vehicle were endoscopically injected into the distal colon. Rats were followed for 11 days. Daily weight, endoscopic score at days 1 and 11, macroscopic appearance at necropsy, colon length and mRNA expression of Foxp3 and IL-10 in mesenteric lymph nodes (MLN) were analyzed.

Results

Endoscopic injection was successful in all the animals. No significant adverse events or mortality due to the procedure occurred. Weight evolution was significantly better in the ASC group, recovering initial weight by day 11 (− 0.8% ± 10.1%, mean ± SD), whereas the vehicle group remained in weight loss (− 6.7% ± 9.2%, p = 0.024). The endoscopic score improved in the ASC group by 47.1% ± 5.3% vs. 21.8% ± 6.6% in the vehicle group (p < 0.01). Stenosis was less frequent in the ASC group (4.8% vs. 41.2%, p < 0.01). Colon length significantly recovered in the ASC group versus the vehicle group (222.6 ± 17.3 mm vs. 193.6 ± 17.9 mm, p < 0.001). The endoscopic score significantly correlated with weight change, macroscopic necropsy score and colon length. Foxp3 and IL-10 mRNA levels in MLN recovered with ASC treatment.

Conclusions

ASC submucosal endoscopic injection is feasible, safe and ameliorates TNBS-induced colitis in rats, especially stenosis.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0837-x) contains supplementary material, which is available to authorized users.

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

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

Advances in mesenchymal stromal cell therapy in the management of Crohn's disease

The aim of therapy in Crohn's disease (CD) is induction and maintenance of remission, promotion of mucosal healing and restoration of quality of life. Even the best treatment regimes, including combinations of biologics and immunomodulators lack durable efficacy and have well documented side effects. Accordingly, there is an unmet need for novel therapies. Mesenchymal stromal cells (MSCs) are a subset of non-hematopoietic stem cells that home to sites of inflammation where they exert potent immunomodulatory effects and contribute to tissue repair. Their utility is being explored in several inflammatory and immune mediated disorders including CD, where they have demonstrated favourable safety, feasibility and efficacy profiles. Areas covered: This review highlights current knowledge on MSC therapy and critically evaluates their safety, efficacy and potential mechanisms of action in CD. Expert commentary: Building on positive early phase clinical trials and a recent phase 3 trial in perianal CD, there is considerable optimism for the possibility of MSCs changing the treatment landscape in complicated CD. Although important questions remain unanswered, including the safety and durability of MSC therapy, optimal adjunctive therapies and their sourcing and manufacturing, it is anticipated that MSCs are likely to enter mainstream treatment algorithms in the near future.

Commensal bacteria make GPCR ligands that mimic human signalling molecules

Commensal bacteria are believed to have important roles in human health. The mechanisms by which they affect mammalian physiology remain poorly understood, but bacterial metabolites are likely to be key components of host interactions. Here we use bioinformatics and synthetic biology to mine the human microbiota for N-acyl amides that interact with G-protein-coupled receptors (GPCRs). We found that N-acyl amide synthase genes are enriched in gastrointestinal bacteria and the lipids that they encode interact with GPCRs that regulate gastrointestinal tract physiology. Mouse and cell-based models demonstrate that commensal GPR119 agonists regulate metabolic hormones and glucose homeostasis as efficiently as human ligands, although future studies are needed to define their potential physiological role in humans. Our results suggest that chemical mimicry of eukaryotic signalling molecules may be common among commensal bacteria and that manipulation of microbiota genes encoding metabolites that elicit host cellular responses represents a possible small-molecule therapeutic modality (microbiome-biosynthetic gene therapy).

Ultrasound-guided Intracardiac Injection of Human Mesenchymal Stem Cells to Increase Homing to the Intestine for Use in Murine Models of Experimental Inflammatory Bowel Diseases

Crohn's disease (CD) is a common chronic inflammatory disease of the small and large intestines. Murine and human mesenchymal stem cells (MSCs) have immunosuppressive potential and have been shown to suppress inflammation in mouse models of intestinal inflammation, even though the route of administration can limit their homing and effectiveness ^1,3,4,5. Local application of MSCs to colonic injury models has shown greater efficacy at ameliorating inflammation in the colon. However, there is paucity of data on techniques to enhance the localization of human bone marrow-derived MSCs (hMSCs) to the small intestine, the site of inflammation in the SAMP-1/YitFc (SAMP) model of experimental Crohn's disease. This work describes a novel technique for the ultrasound-guided intracardiac injection of hMSCs in SAMP mice, a well-characterized spontaneous model of chronic intestinal inflammation. Sex- and age-matched, inflammation-free AKR/J (AKR) mice were used as controls. To analyze the biodistribution and the localization, hMSCs were transduced with a lentivirus containing a triple reporter. The triple reporter consisted of firefly luciferase (fl), for bioluminescent imaging; monomeric red fluorescent protein (mrfp), for cell sorting; and truncated herpes simplex virus thymidine kinase (ttk), for positron emission tomography (PET) imaging. The results of this study show that 24 h after the intracardiac administration, hMSCs localize in the small intestine of SAMP mice as opposed to inflammation-free AKR mice. This novel, ultrasound-guided injection of hMSCs in the left ventricle of SAMP mice ensures a high success rate of cell delivery, allowing for the rapid recovery of mice with minimal morbidity and mortality. This technique could be a useful method for the enhanced localization of MSCs in other models of small-intestinal inflammation, such as TNFΔRE⁶. Future studies will determine if the increased localization of hMSCs by intra-arterial delivery can lead to increased therapeutic efficacy.

ROS in gastrointestinal inflammation: Rescue Or Sabotage?

The intestine is composed of many distinct cell types that respond to commensal microbiota or pathogens with immune tolerance and proinflammatory signals respectively. ROS produced by mucosa-resident cells or by newly recruited innate immune cells are essential for antimicrobial responses and regulation of signalling pathways including processes involved in wound healing. Impaired ROS production due to inactivating patient variants in genes encoding NADPH oxidases as ROS source has been associated with Crohn's disease and pancolitis, whereas overproduction of ROS due to up-regulation of oxidases or altered mitochondrial function was linked to ileitis and ulcerative colitis. Here, we discuss recent advances in our understanding of how maintaining a redox balance is crucial to preserve gut homeostasis.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

Mesenchymal Cells in Colon Cancer

Mesenchymal cells in the intestine comprise a variety of cell types of diverse origins, functions, and molecular markers. They provide mechanical and structural support and have important functions during intestinal organogenesis, morphogenesis, and homeostasis. Recent studies of the human transcriptome have revealed their importance in the development of colorectal cancer, and studies from animal models have provided evidence for their roles in the pathogenesis of colitis-associated cancer and sporadic colorectal cancer. Mesenchymal cells in tumors, called cancer-associated fibroblasts, arise via activation of resident mesenchymal cell populations and the recruitment of bone marrow-derived mesenchymal stem cells and fibrocytes. Cancer-associated fibroblasts have a variety of activities that promote colon tumor development and progression; these include regulation of intestinal inflammation, epithelial proliferation, stem cell maintenance, angiogenesis, extracellular matrix remodeling, and metastasis. We review the intestinal mesenchymal cell-specific pathways that regulate these processes, with a focus on their roles in mediating interactions between inflammation and carcinogenesis. We also discuss how increasing our understanding of intestinal mesenchymal cell biology and function could lead to new strategies to identify and treat colitis-associated cancers.

The Wae to repair: prostaglandin E2 (PGE2) triggers intestinal wound repair

Accurate wound repair is a crucial step to protect organisms from environmental damage, for example infection and toxin exposure. In this issue of The EMBO Journal , Miyoshi et al (2017 ) have elucidated a new mechanism underpinning this process within the intestine where mesenchymal prostaglandin E2 produced following damage drives intestinal regeneration.

Wnt-expressing cells in the intestines: guides for tissue remodeling

The crypt is a minimal functional unit in the intestinal epithelium. This unique structure is maintained by surrounding mesenchymal cells that focally interact with associated epithelial cells. Canonical and non-canonical Wnt ligands enable specific microenvironments localized to each end of the crypt major axis. While canonical Wnt-expressing cells are localized near the crypt bottom where intestinal stem cells reside, non-canonical Wnt-expressing cells are positioned beneath the luminal surface of epithelial cells. During wound healing, propagation and appropriate relocation of each cell population are thought to ensure subsequent crypt regeneration. In this review, I integrate information from recent studies on Wnt-expressing cells and intestinal fibroblast lineages and discuss their roles in homeostasis and wound healing. More information on the lineages of Wnt-expressing cells will help clarify the mechanisms of epithelial tissue formation.

Eicosanoids: Emerging contributors in stem cell-mediated wound healing

Eicosanoids are bioactive lipid products primarily derived from the oxidation of arachidonic acid (AA). The individual contributions of eicosanoids and stem cells to wound healing have been of great interest. This review focuses on how stem cells work in concert with eicosanoids to create a beneficial environment in the wound bed and in the promotion of wound healing. Stem cells contribute to wound healing through modulating inflammation, differentiating into skin cells or endothelial cells, and exerting paracrine effects by releasing various potent growth factors. Eicosanoids have been shown to stimulate proliferation, migration, homing, and differentiation of stem cells, all of which contribute to the process of wound healing. Increasing evidence has shown that eicosanoids improve wound healing through increasing stem cell densities, stimulating differentiation, and enhancing the angiogenic properties of stem cells. Chronic wounds have become a major problem in health care. Therefore, research regarding the effects of stem cells and eicosanoids in the promotion wound healing is of great importance.