Cultured human skeletal muscle satellite cells exhibit characteristics of mesenchymal stem cells and play anti-inflammatory roles through prostaglandin E2 and hepatocyte growth factors

Epigenetic control of myogenic identity of human muscle stem cells in Duchenne muscular dystrophy

In Duchenne muscular dystrophy (DMD), muscle stem cells' (MuSCs) regenerative capacities are overwhelmed leading to fibrosis. Whether MuSCs have intrinsic defects or are disrupted by their environment is unclear. We investigated cell behavior and gene expression of MuSCs from DMD or healthy human muscles. Proliferation, differentiation, and fusion were unaltered in DMD-MuSCs, but with time, they lost their myogenic identity twice as fast as healthy MuSCs. The rapid drift toward a fibroblast-like cell identity was observed at the clonal level, and resulted from altered expression of epigenetic enzymes. Re-expression of CBX3, SMC3, H2AFV, and H3F3B prevented the MuSC identity drift. Among epigenetic changes, a closing of chromatin at the transcription factor MEF2B locus caused downregulation of its expression and loss of the myogenic fate. Re-expression of MEF2B in DMD-MuSCs restored their myogenic fate. MEF2B is key in the maintenance of myogenic identity in human MuSCs, which is altered in DMD.

Muscle-Derived Stem/Progenitor Cells Ameliorate Acute Kidney Injury in Rats through the Anti-Apoptotic Pathway and Demonstrate Comparable Effects to Bone Marrow Mesenchymal Stem Cells

Background and Objectives: To date, the therapeutic potential of skeletal muscle-derived stem/progenitor cells (MDSPCs) for acute kidney injury (AKI) has only been evaluated by our research group. We aimed to compare MDSPCs with bone marrow mesenchymal stem cells (BM-MSCs) and evaluate their feasibility for the treatment of AKI. Materials and Methods: Rats were randomly assigned to four study groups: control, GM (gentamicin) group, GM+MDSPCs, and GM+BM-MSCs. AKI was induced by gentamicin (80 mg/kg/day; i.p.) for 7 consecutive days. MDSPCs and BM-MSCs were injected 24 h after the last gentamicin injection. Kidney parameters were determined on days 0, 8, 14, 21, and 35. Results: MDSPCs and BM-MSCs accelerated functional kidney recovery, as reflected by significantly lower serum creatinine levels and renal injury score, higher urinary creatinine and creatinine clearance levels (p < 0.05), lower TUNEL-positive cell number, and decreased KIM-1 and NGAL secretion in comparison to the non-treated AKI group. There was no significant difference in any parameters between the MDSPCs and BM-MSCs groups (p > 0.05). Conclusions: MDSPCs and BM-MSCs can migrate and incorporate into injured renal tissue, resulting in a beneficial impact on functional and morphological kidney recovery, which is likely mediated by the secretion of paracrine factors and an anti-apoptotic effect. MDSPCs were found to be non-inferior to BM-MSCs and therefore can be considered as a potential candidate strategy for the treatment of AKI.

EMR1/ADGRE1 Expression in Cancer Cells Upregulated by Tumor-Associated Macrophages Is Related to Poor Prognosis in Colorectal Cancer

EMR1, a member of the adhesion G protein-coupled receptor family (ADGRE1), is a macrophage marker that is abnormally expressed in cancer cells. However, its clinical significance in colorectal cancer (CRC) is not well-known. In this investigation, EMR1 expression in tumor cells (EMR1-TC) was found in 91 (22.8%) of the 399 CRC samples tested by immunohistochemical staining and showed a significant relationship with lymph node metastasis. Furthermore, EMR1-TC was significantly associated with CD68⁺ CD163⁺ tumor-associated macrophages (TAMs), and CRC with a high combined EMR1-TC⁺CD68⁺CD163⁺ score showed worse recurrence-free survival prognosis. In an in vitro co-culture assay of colon cancer cells with myeloid cells, we found that EMR1 expression significantly upregulated in cancer cells was induced by macrophages. In addition, there was increased expression of M2 markers (CD163 and interleukin-6 & 10) in myeloid portion, while that of M1 markers (CD86 and iNOS) remained unchanged. Accordingly, upon treatment with M2 macrophage polarization inhibitors (O-ATP, trametinib, bardoxolone methyl), EMR1 expression reduced significantly, along with M2 markers (CD163 and interleukin-6 & 10). In conclusion, EMR1-TC was a high-risk factor for lymph node metastasis and correlated with poor recurrence free survival, particularly in patients with TAM-rich CRC. Furthermore, EMR1 expression in colon cancer cells may be related to M2 macrophage polarization and vice versa.

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.