PD-L1 expression levels in mesenchymal stromal cells predict their therapeutic values for autoimmune hepatitis

Regenerative Functions of Regulatory T Cells and Current Strategies Utilizing Mesenchymal Stem Cells in Immunomodulatory Tissue Regeneration

BACKGROUND

Regulatory T cells (Tregs) are essential for maintaining immune homeostasis and facilitating tissue regeneration by fostering an environment conducive to tissue repair. However, in damaged tissues, excessive inflammatory responses can overwhelm the immunomodulatory capacity of Tregs, compromising their functionality and potentially hindering effective regeneration. Mesenchymal stem cells (MSCs) play a key role in enhancing Treg function. MSCs enhance Treg activity through indirect interactions, such as cytokine secretion, and direct interactions via membrane proteins.

METHODS

This review examines the regenerative functions of Tregs across various tissues, including bone, cartilage, muscle, and skin, and explores strategies to enhance Treg functionality using MSCs. Advanced techniques, such as the overexpression of relevant genes in MSCs, are highlighted for their potential to further enhance Treg function. Additionally, emerging technologies utilizing extracellular vesicles (EVs) and cell membrane-derived vesicles derived from MSCs offer promising alternatives to circumvent the potential side effects associated with live cell therapies. This review proposes approaches to enhance Treg function and promote tissue regeneration and also outlines future research directions.

RESULTS AND CONCLUSION

This review elucidates recent technological advancements aimed at enhancing Treg function using MSCs and examines their potential to improve tissue regeneration efficiency.

Mesenchymal stem cell therapy as a game-changer in liver diseases: review of current clinical trials

Chronic liver diseases, including cirrhosis and liver failure, remain formidable challenges due to their complex progression and limited therapeutic options. Mesenchymal stem cell (MSC) therapy has emerged as a game-changing approach, leveraging its potent immunomodulatory, anti-fibrotic, and regenerative capabilities, along with the ability to transdifferentiate into hepatocytes. This review delves into the latest advances in MSC-based treatments for chronic and end-stage liver diseases, as highlighted in current clinical trials. MSCs derived from bone marrow and umbilical cord have shown remarkable promise in reversing liver damage, improving liver function, and providing hope for patients who do not respond to conventional therapies. When administered through hepatic, portal, or peripheral veins, MSCs have significantly improved liver histology, reduced fibrosis, and restored functional capacity. Furthermore, MSC-derived materials, such as extracellular vesicles and exosomes, are emerging as cutting-edge tools for treating liver failure and mitigating post-transplant complications. While autologous MSC-derived hepatocytes hold promise for non-fatal cirrhosis, allogeneic MSCs are being applied in more severe conditions, including liver failure and transplantation cases. Despite these promising early outcomes, larger trials and long-term studies are essential to fully harness MSCs as a transformative, off-the-shelf alternative to liver transplantation, heralding a new era in regenerative liver therapies.

Expression, regulation, and function of PD-L1 on non-tumor cells in the tumor microenvironment

Antiprogrammed death ligand 1 (PD-L1) therapy is a leading immunotherapy, but only some patients with solid cancers benefit. Overwhelming evidence has revealed that PD-L1 is expressed on various immune cells in the tumor microenvironment (TME), including macrophages, dendritic cells, and regulatory T cells, modulating tumor immunity and influencing tumor progression. PD-L1 can also be located on tumor cell membranes as well as in exosomes and cytoplasm. Accordingly, the dynamic expression and various forms of PD-L1 might explain the therapy's limited efficacy and resistance. Herein a systematic summary of the expression of PD-L1 on different immune cells and their regulatory mechanisms is provided to offer a solid foundation for future studies.

Restoration of functional endometrium in an intrauterine adhesion rat model with endometrial stromal cells transplantation

BACKGROUND

Intrauterine adhesion (IUA) as a prevalent gynecological disease is developed from infection or trauma. However, therapeutic strategies to repair damaged endometrium are relatively limited. Emerging studies have shed light on the crucial role of endometrial stromal cells (EnSCs) in the process of uterine endometrial regeneration. EnSCs isolated from the uterine endometrium have similar characteristics to mesenchymal stem cells (MSCs). However, it is still unknown whether EnSCs could be used as donor cells to treat IUA. The aim of this study was to evaluate the potential efficacy of EnSCs in treating rat IUA.

METHODS

Human EnSCs were isolated from the endometrial tissue of healthy female donors and subjected to extensive expansion and culture in vitro. Immunofluorescence, flow cytometry, cell proliferation assay, trilineage differentiation experiment, and decidualization assay were used to characterize the biological properties of EnSCs. We evaluated the immunoregulatory potential of EnSCs by analyzing their secreted cytokines and conducting bulk RNA sequencing after IFN-γ treatment. After EnSCs were transplanted into the uterine muscle layer in IUA rats, their therapeutic effects and underlying mechanisms were analyzed using histological analysis, Q-PCR, fertility and pregnancy outcome assay, and transcriptome analysis.

RESULTS

We successfully isolated EnSCs from the endometrium of human donors and largely expanded in vitro. EnSCs exhibited characteristics of mesenchymal stem cells and retained responsiveness to sex hormones. Following IFN-γ stimulation, EnSCs upregulated the anti-inflammatory cytokines and activated immunosuppressive molecules. Xenogeneic transplantation of EnSCs successfully repaired injured endometrium and significantly restored the pregnancy rate in IUA rats. Mechanistically, the therapeutic effects of EnSCs on IUA endometrium functioned through anti-inflammation, anti-fibrosis and the secretion of regeneration factor.

CONCLUSIONS

Due to their large expansion ability, immunoregulatory properties, and great potential in treating IUA, EnSCs, as a valuable source of donor cells, could offer a potential treatment avenue for injury-induced IUA.

The impact of 5-aminosalicylates on the efficacy of mesenchymal stem cell therapy in a murine model of ulcerative colitis

Inflammatory bowel disease (IBD) is distinguished by persistent immune-mediated inflammation of the gastrointestinal tract. Previous experimental investigations have shown encouraging outcomes for the use of mesenchymal stem cell (MSC)-based therapy in the treatment of IBD. However, as a primary medication for IBD patients, there is limited information regarding the potential interaction between 5-aminosalicylates (5-ASA) and MSCs. In this present study, we employed the dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mouse model to examine the influence of a combination of MSCs and 5-ASA on the development of UC. The mice were subjected to weight measurement, DAI scoring, assessment of calprotectin expression, and collection of colons for histological examination. The findings revealed that both 5-ASA and MSCs have demonstrated efficacy in the treatment of UC. However, it is noteworthy that 5-ASA exhibits a quicker onset of action, while MSCs demonstrate more advantageous and enduring therapeutic effects. Additionally, the combination of 5-ASA and MSC treatment shows a less favorable efficacy compared to the MSCs alone group. Moreover, our study conducted in vitro revealed that 5-ASA could promote MSC migration, but it could also inhibit MSC proliferation, induce apoptosis, overexpress inflammatory factors (IL-2, IL-12P70, and TNF-α), and reduce the expression of PD-L1 and PD-L2. Furthermore, a significant decrease in the viability of MSCs within the colon was observed as a result of 5-ASA induction. These findings collectively indicate that the use of 5-ASA has the potential to interfere with the therapeutic efficacy of MSC transplantation for the treatment of IBD.

Therapeutic and immunomodulatory potentials of mesenchymal stromal/stem cells and immune checkpoints related molecules

Mesenchymal stromal/stem cells (MSCs) are used in many studies due to their therapeutic potential, including their differentiative ability and immunomodulatory properties. These cells perform their therapeutic functions by using various mechanisms, such as the production of anti-inflammatory cytokines, growth factors, direct cell-to-cell contact, extracellular vesicles (EVs) production, and mitochondrial transfer. However, mechanisms related to immune checkpoints (ICPs) and their effect on the immunomodulatory ability of MSCs are less discussed. The main function of ICPs is to prevent the initiation of unwanted responses and to regulate the immune system responses to maintain the homeostasis of these responses. ICPs are produced by various types of immune system regulatory cells, and defects in their expression and function may be associated with excessive responses that can ultimately lead to autoimmunity. Also, by expressing different types of ICPs and their ligands (ICPLs), tumor cells prevent the formation and durability of immune responses, which leads to tumors' immune escape. ICPs and ICPLs can be produced by MSCs and affect immune cell responses both through their secretion into the microenvironment or direct cell-to-cell interaction. Pre-treatment of MSCs in inflammatory conditions leads to an increase in their therapeutic potential. In addition to the effect that inflammatory environments have on the production of anti-inflammatory cytokines by MSCs, they can increase the expression of various types of ICPLs. In this review, we discuss different types of ICPLs and ICPs expressed by MSCs and their effect on their immunomodulatory and therapeutic potential.