HGF and TSG-6 Released by Mesenchymal Stem Cells Attenuate Colon Radiation-Induced Fibrosis

Adipose Tissue-Derived Mesenchymal Stem Cell Inhibits Osteoclast Differentiation through Tumor Necrosis Factor Stimulated Gene-6

BACKGROUND

Mesenchymal stem cells (MSCs) have been highlighted as a potent therapeutic option for conditions with excessive osteoclast activity such as systemic and local bone loss in rheumatic disease. In addition to their immunomodulatory functions, MSCs also directly suppress osteoclast differentiation and activation by secreting osteoprotegerin (OPG) and IL-10 but the underlying mechanisms are still to be clarified. Tumor necrosis factor-stimulated gene-6 (TSG-6) is a potent anti-inflammatory molecule that inhibits osteoclast activation and has been shown to mediate MSC's immunomodulatory functions. In this study, we aimed to determine whether adipose tissue-derived MSC (ADMSC) inhibits the differentiation from osteoclast precursors to mature osteoclasts through TSG-6.

METHODS

Human ADMSCs were co-cultured with bone marrow-derived monocyte/macrophage (BMMs) from DBA/1J or B6 mouse in the presence of osteoclastogenic condition (M-CSF 10 ng/mL and RANKL 10 ng/mL). In some co-culture groups, ADMSCs were transfected with siRNA targeting TSG-6 or OPG to determine their role in osteoclastogenesis. Tartrate-resistant acid phosphatase (TRAP) activity in culture supernatant and mRNA expression of osteoclast markers were investigated. TRAP+ multinucleated cells and F-actin ring formation were counted.

RESULTS

ADMSCs significantly inhibited osteoclast differentiation under osteoclastogenic conditions. Suppression of TSG-6 significantly reversed the inhibition of osteoclast differentiation in a degree similar to that of OPG based on TRAP activity, mRNA expression of osteoclast markers, and numbers of TRAP+ multinucleated cell and F-actin ring formation.

CONCLUSION

This study demonstrated that ADMSCs inhibit osteoclast differentiation through TSG-6 under osteoclastogenic conditions.

Mesenchymal stem cells derived from adipose tissue and umbilical cord reveal comparable efficacy upon radiation-induced colorectal fibrosis in rats

Chemoradiotherapy (CRT) and radiotherapy (RT) have served as anticancer treatments and neoadjuvant therapies for conquering multimodal rectal cancers including colorectal carcinoma (CRC), yet the concomitant radiation-induced colorectal fibrosis (RICF) has caused chronic toxicity and stenosis in the colorectal mucosa of patients. Mesenchymal stem/stromal cells (MSCs) with unique bidirectional immunoregulation and anti-fibrotic effect have been recognized as splendid sources for regenerative purposes including intestinal diseases. Herein, we are aiming to verify the feasibility and variations of MSC-based cytotherapy for the remission of RICF from the pathological features and the potential impact upon the transcriptomic signatures of RICF rats. For the purpose, we utilized our well-established RICF Sprague-Dawley (SD) rats by radiation for five weeks, and conducted consecutive intraperitoneal injection of two distinct MSCs for treatment, including MSCs derived from adult adipose tissue (AD-MSCs) and perinatal umbilical cord (UC-MSCs). On the one hand, the efficacy of AD-MSCs and UC-MSCs was assessed by diverse indicators, including weight change, pathological detections (e.g., H&E staining, Masson staining, EVG staining, IF staining, and IHC staining), and proinflammatory and fibrotic factor expression. On the other hand, we turned to RNA-sequencing (RNA-SEQ) and multifaceted bioinformatics analyses (e.g., GOBP, Venn Map, KEGG, and GSEA) to compare the impact of AD-MSC and UC-MSC treatment upon the gene expression profiling and genetic variations. RICF rats after consecutive AD-MSC and UC-MSC administration revealed comparable remission in histopathogenic features and significant suppression of diverse proinflammatory and fibrotic factors expression. Meanwhile, RICF rats after both MSC treatment revealed decrease and variations in the alterations in diverse gene expression and somatic mutations compared to RICF rats. Collectively, our data indicated the comparable therapeutic effect of AD-MSCs and UC-MSCs upon RICF in SD rats, together with the conservations in gene expression profiling and the diverse variations in genetic mutations. Our findings indicated the multifaceted impact of MSC infusion for the supervision of RICF both at the therapeutic and transcriptomic levels, which would provide novel references for the further evaluation and development of MSC-based regimens in future.

Radiation-Induced Intestinal Injury: Injury Mechanism and Potential Treatment Strategies

Radiation-induced intestinal injury (RIII) is one of the most common intestinal complications caused by radiotherapy for pelvic and abdominal tumors and it seriously affects the quality of life of patients. However, the treatment of acute RIII is essentially symptomatic and nutritional support treatment and an ideal means of prevention and treatment is lacking. Researchers have conducted studies at the cellular and animal levels and found that some chemical or biological agents have good therapeutic effects on RIII and may be used as potential candidates for clinical treatment. This article reviews the injury mechanism and potential treatment strategies based on cellular and animal experiments to provide new ideas for the diagnosis and treatment of RIII in clinical settings.

Tissue fibrosis induced by radiotherapy: current understanding of the molecular mechanisms, diagnosis and therapeutic advances

Cancer remains the leading cause of death around the world. In cancer treatment, over 50% of cancer patients receive radiotherapy alone or in multimodal combinations with other therapies. One of the adverse consequences after radiation exposure is the occurrence of radiation-induced tissue fibrosis (RIF), which is characterized by the abnormal activation of myofibroblasts and the excessive accumulation of extracellular matrix. This phenotype can manifest in multiple organs, such as lung, skin, liver and kidney. In-depth studies on the mechanisms of radiation-induced fibrosis have shown that a variety of extracellular signals such as immune cells and abnormal release of cytokines, and intracellular signals such as cGAS/STING, oxidative stress response, metabolic reprogramming and proteasome pathway activation are involved in the activation of myofibroblasts. Tissue fibrosis is extremely harmful to patients' health and requires early diagnosis. In addition to traditional serum markers, histologic and imaging tests, the diagnostic potential of nuclear medicine techniques is emerging. Anti-inflammatory and antioxidant therapies are the traditional treatments for radiation-induced fibrosis. Recently, some promising therapeutic strategies have emerged, such as stem cell therapy and targeted therapies. However, incomplete knowledge of the mechanisms hinders the treatment of this disease. Here, we also highlight the potential mechanistic, diagnostic and therapeutic directions of radiation-induced fibrosis.

Evaluation of in vivo and ex vivo pre-treated bone marrow-derived mesenchymal stem cells with resveratrol in streptozotocin-induced type 1 diabetic rats

OBJECTIVES

To compare the therapeutic potential of rat bone marrow-derived mesenchymal stem cells (BM-MSCs) preconditioned ex-vivo with resveratrol (MCR) and BM-MSCs isolated from resveratrol-pre-treated rats (MTR) in type-1 diabetic rats.

METHODS

Type-1 diabetes was induced by a single streptozotocin injection (50 mg/kg; ip) in 24 rats. Following the confirmation of T1DM, diabetic rats were randomly divided into four groups: diabetic control (DC), diabetic rats treated with insulin subcutaneous (7.5 IU/kg/day), diabetic rats treated with MCR cells (3 × 106cells/rat, intravenous) and diabetic rats treated with MTR cells (3 × 106cells/rat, intravenous). Rats were sacrificed 4 weeks following cellular transplantation.

KEY FINDINGS

Untreated diabetic rats suffered from pancreatic cell damage, had high blood glucose levels, increased apoptotic, fibrosis, and oxidative stress markers and decreased survival and pancreatic regeneration parameters. Both MSCs preconditioned ex-vivo with RES and MSCs isolated from rats pre-treated with RES homed successfully in injured pancreas and showed therapeutic potential in the treatment of STZ-induced T1DM. MCR cells showed better efficiency than MTR cells.

CONCLUSIONS

The pre-conditioning of BM-MSCs with resveratrol may be a promising therapeutic possibility in T1DM. Resveratrol-preconditioned BM-MSCs encouraged effects almost comparable to that of exogenous insulin with the advantages of cured pancreas and restored islets not attained by insulin.

hucMSC-Ex Alleviates IBD-Associated Intestinal Fibrosis by Inhibiting ERK Phosphorylation in Intestinal Fibroblasts

Background

Intestinal fibrosis, one of the complications of inflammatory bowel disease (IBD), is associated with fistula and intestinal stricture formation. There are currently no treatments for fibrosis. Mesenchymal stem cell-derived exosomes have been proven to exert inhibitory and reversal effects in IBD and other organ fibrosis. In this study, we explored the role of human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-Ex) in IBD-related fibrosis and its associated mechanism to provide new ideas for the prevention and treatment of IBD-related intestinal fibrosis.

Methods

We established a DSS-induced mouse IBD-related intestinal fibrosis model and observed the effect of hucMSC-Ex on the mouse model. We also used the TGF-induced human intestinal fibroblast CCD-18Co to observe the role of hucMSC-Ex in the proliferation, migration, and activation of intestinal fibroblasts. Having observed that the extracellular-signal-regulated kinase (ERK) pathway in intestinal fibrosis can be inhibited by hucMSC-Ex, we treated intestinal fibroblasts with an ERK inhibitor to emphasize the potential target of ERK phosphorylation in the treatment of IBD-associated intestinal fibrosis.

Results

In the animal model of IBD-related fibrosis, hucMSC-Ex alleviated inflammation-related fibrosis as evident in the thinning of the mice's intestinal wall and decreased expression of related molecules. Moreover, hucMSC-Ex inhibited TGF-β-induced proliferation, migration, and activation of human intestinal fibroblasts, and ERK phosphorylation played a key role in IBD-associated fibrosis. The inhibition of ERK decreased the expression of fibrosis-related indicators such as α-SMA, fibronectin, and collagen I.

Conclusion

hucMSC-Ex alleviates DSS-induced IBD-related intestinal fibrosis by inhibiting profibrotic molecules and intestinal fibroblast proliferation and migration by decreasing ERK phosphorylation.

Mesenchymal stem cells limit vascular and epithelial damage and restore the impermeability of the urothelium in chronic radiation cystitis

BACKGROUND

Cellular therapy seems to be an innovative therapeutic alternative for which mesenchymal stem cells (MSCs) have been shown to be effective for interstitial and hemorrhagic cystitis. However, the action of MSCs on chronic radiation cystitis (CRC) remains to be demonstrated. The aim of this study was to set up a rat model of CRC and to evaluate the efficacy of MSCs and their mode of action.

METHODS

CRC was induced by single-dose localized irradiation of the whole bladder using two beams guided by tomography in female Sprague-Dawley rat. A dose range of 20-80 Gy with follow-up 3-12 months after irradiation was used to characterize the dose effect and the kinetics of radiation cystitis in rats. For the treatment, the dose of 40 Gy was retained, and in order to potentiate the effect of the MSCs, MSCs were isolated from adipose tissue. After expansion, they were injected intravenously during the pre-chronic phase. Three injections of 5 million MSCs were administered every fortnight. Follow-up was performed for 12 months after irradiation.

RESULTS

We observed that the intensity and frequency of hematuria are proportional to the irradiation dose, with a threshold at 40 Gy and the appearance of bleeding from 100 days post-irradiation. The MSCs reduced vascular damage as well as damage to the bladder epithelium.

CONCLUSIONS

These results are in favor of MSCs acting to limit progression of the chronic phase of radiation cystitis. MSC treatment may afford real hope for all patients suffering from chronic radiation cystitis resistant to conventional treatments.

TSG-6 (Tumor Necrosis Factor-α-Stimulated Gene/Protein-6): An Emerging Remedy for Renal Inflammation

The inflammatory response is a major pathological feature in most kidney diseases and often evokes compensatory mechanisms. Recent evidence suggests that TSG-6 (tumor necrosis factor-α-stimulated gene/protein-6) plays a pivotal role in anti-inflammation in various renal diseases, including immune-mediated and nonimmune-mediated renal diseases. TSG-6 has a diverse repertoire of anti-inflammatory functions: it potentiates antiplasmin activity of IαI (inter-α-inhibitor) by binding to its light chain, crosslinks hyaluronan to promote its binding to cell surface receptor CD44, and thereby regulate the migration and adhesion of lymphocytes, inhibits chemokine-stimulated transendothelial migration of neutrophils by directly interacting with the glycosaminoglycan binding site of CXCL8 (CXC motif chemokine ligand-8), and upregulates COX-2 (cyclooxygenase-2) to produce anti-inflammatory metabolites. Hopefully, further developments can target this anti-inflammatory molecule to the kidney and harness its remedial properties. This review provides an overview of the emerging role of TSG-6 in blunting renal inflammation.

Combinational Treatment Involving Decellularized Extracellular Matrix Hydrogels With Mesenchymal Stem Cells Increased the Efficacy of Cell Therapy in Pancreatitis

Cell transplantation using mesenchymal stem cells (MSCs) has emerged as a promising approach to repairing and regenerating injured or impaired organs. However, the survival and retention of MSCs following transplantation remain a challenge. Therefore, we investigated the efficacy of co-transplantation of MSCs and decellularized extracellular matrix (dECM) hydrogels, which have high cytocompatibility and biocompatibility. The dECM solution was prepared by enzymatic digestion of an acellular porcine liver scaffold. It could be gelled and formed into porous fibrillar microstructures at physiological temperatures. MSCs expanded three-dimensionally in the hydrogel without cell death. Compared to the 2-dimensional cell culture, MSCs cultured in the hydrogel showed increased secretion of hepatocyte growth factor (HGF) and tumor necrosis factor-inducible gene 6 protein (TSG-6), both of which are major anti-inflammatory and anti-fibrotic paracrine factors of MSCs, under TNFα stimulation. In vivo experiments showed that the co-transplantation of MSCs with dECM hydrogel improved the survival rate of engrafted cells compared to those administered without the hydrogel. MSCs also demonstrated therapeutic effects in improving inflammation and fibrosis of pancreatic tissue in a dibutyltin dichloride (DBTC)-induced rat pancreatitis model. Combinational use of dECM hydrogel with MSCs is a new strategy to overcome the challenges of cell therapy using MSCs and can be used for treating chronic inflammatory diseases in clinical settings.

Antifibrotic TSG-6 Expression Is Synergistically Increased in Both Cells during Coculture of Mesenchymal Stem Cells and Macrophages via the JAK/STAT Signaling Pathway

The pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-1β upregulate TNF-α-stimulated gene 6 (TSG-6); however, current knowledge about the optimal conditions for TSG-6 expression in mesenchymal stem cells (MSCs) is limited. Here, we investigated whether TSG-6 expression varies depending on the polarization state of macrophages co-cultured with adipose tissue-derived stem cells (ASCs) and analyzed the optimal conditions for TSG-6 expression in ASCs. TSG-6 expression increased in ASCs co-cultured with M0, M1, and M2 macrophages indirectly; among them, M1 macrophages resulted in the highest increase in TSG-6 expression in ASCs. TSG-6 expression in ASCs dramatically increased by combination (but not single) treatment of TNF-α, IL-1β, interferon-gamma (IFN-γ), and lipopolysaccharide (LPS). In addition, phosphorylation of signal transducer and activator of transcription (STAT) 1/3 was observed in response to IFN-γ and LPS treatment but not TNF-α and/or IL-1β. STAT1/3 activation synergistically increased TNF-α/IL-1β-dependent TSG-6 expression, and JAK inhibitors suppressed TSG-6 expression both in ASCs and macrophages. In LX-2 hepatic stellate cells, TSG-6 inhibited TGF-β-induced Smad3 phosphorylation, resulting in decreased α-smooth muscle actin (SMA) expression. Moreover, fibrotic activities of LX-2 cells induced by TGF-β were dramatically decreased after indirect co-culture with ASCs and M1 macrophages. These results suggest that a comprehensive inflammatory microenvironment may play an important role in determining the therapeutic properties of ASCs by increasing TSG-6 expression through STAT1/3 activation.

hUC-MSCs Attenuate Acute Graft-Versus-Host Disease through Chi3l1 Repression of Th17 Differentiation

Mesenchymal stem cells (MSCs) have already demonstrated definitive evidence of their clinical benefits in acute graft-versus-host disease (aGvHD) and other inflammatory diseases. However, the comprehensive mechanism of MSCs' immunomodulation properties has not been elucidated. To reveal their potential immunosuppressive molecules, we used RNA sequencing to analyze gene expression in different tissue-derived MSCs, including human bone marrow, umbilical cord, amniotic membrane, and placenta, and found that chitinase-3-like protein 1 (Chi3l1) was highly expressed in human umbilical cord mesenchymal stem cells (hUC-MSCs). We found that hUC-MSCs treated with interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) exhibited increased expression of Chi3l1 and concurrently repressed T-helper 17 cell (Th17) differentiation through inhibition of signal transducer and activator of transcription 3 (STAT3) activation. Furthermore, Chi3l1 knockdown hUC-MSCs exhibited impaired therapeutic efficacy in aGvHD mice with an increased inflammatory response by promoting Th17 cell differentiation, including an increase in IL-17A in the spleen, intestine, and serum. Collectively, these results reveal a new immunosuppressive molecule, Chi3l1, in hUC-MSCs in the treatment of aGvHD that regulates Th17 differentiation and inhibits STAT3 activation. These novel insights into the mechanisms of hUC-MSC immunoregulation may lead to the consistent production of hUC-MSCs with strong immunosuppressive functions and thus improved clinical utility.

Intestinal Fibrosis in Inflammatory Bowel Disease and the Prospects of Mesenchymal Stem Cell Therapy

Intestinal fibrosis is an important complication of inflammatory bowel disease (IBD). In the course of the development of fibrosis, certain parts of the intestine become narrowed, significantly destroying the structure and function of the intestine and affecting the quality of life of patients. Chronic inflammation is an important initiating factor of fibrosis. Unfortunately, the existing anti-inflammatory drugs cannot effectively prevent and alleviate fibrosis, and there is no effective anti-fibrotic drug, which makes surgical treatment the mainstream treatment for intestinal fibrosis and stenosis. Mesenchymal stem cells (MSCs) are capable of tissue regeneration and repair through their self-differentiation, secretion of cytokines, and secretion of extracellular vesicles. MSCs have been shown to play an important therapeutic role in the fibrosis of many organs. However, the role of MSC in intestinal fibrosis largely remained unexplored. This review summarizes the mechanism of intestinal fibrosis, including the role of immune cells, TGF-β, and the gut microbiome and metabolites. Available treatment options for fibrosis, particularly, MSCs are also discussed.

Recombinant TSG-6 protein inhibits the growth of capsule fibroblasts in frozen shoulder via suppressing the TGF-β/Smad2 signal pathway

Background

The tumor necrosis factor-stimulated gene-6 (TSG-6) has been confirmed to inhibit inflammation. It is now generally accepted that local inflammatory stimulation around shoulder capsule causes proliferative fibrosis. This study aims to investigate the mechanism of recombinant TSG-6 protein inhibiting the growth of capsule fibroblasts in frozen shoulder via the TGF-β/Smad2 signal pathway.

Methods

Human frozen shoulder capsule tissue was taken for primary and passage culture, and the 3rd generation fibroblasts from pathological frozen shoulder capsule were treated with different concentrations of recombinant TSG-6 protein, or with TGF-β1 agonist SRI-011381. Immunoconfocal analysis was used to identify the isolated fibroblasts, and MTT assay, colony formation assay, and flow cytometry were used to detect the viability, proliferation, and apoptosis rate of fibroblast. The contents of fibrosis and inflammation indexes COL1A1, TNF-α, IL-6, and IL-1β in the cell supernatant were detected using ELISA and then further examined by qRT-PCR. The expression of Bax, Bcl-2, and proteins related to TGF-β/Smad2 pathway were detected by Western Blot.

Results

Compared with the blank control group, fibroblasts intervened with TSG-6 (2 μg and 5 μg) showed significantly decreased viability and proliferation ability and enhanced cell apoptosis, concurrent with the reductions in Bcl-2 expression; COL1A1, TNF-α, IL-6, and IL-1β levels; and the expression of TGF-β1 and phosphorylated Smad22, and an increase in Bax expression, while SRI-011381 treatment would reverse the effect of recombinant TSG-6 protein.

Conclusion

Recombinant TSG-6 protein inhibited the growth of primary fibroblasts from human frozen shoulder capsule by suppressing the TGF-β/Smad2 signaling pathway.