Adenosine production in mesenchymal stromal cells in relation to their developmental status

Human placental mesenchymal stromal cells alleviate intestinal oxidative damage in mice with graft-versus-host disease via CD73/adenosine/PI3K/Akt/GSK-3β axis

BACKGROUND

Intestinal damage is a common and serious complication in patients with graft-versus-host disease (GVHD). Human placental mesenchymal stromal cells (hPMSCs) ameliorate GVHD tissue damage by exerting anti-oxidative effects; however, the underlying mechanisms remain not fully clear.

METHODS

A GVHD mouse model and tumor necrosis factor-α (TNF-α)-stimulated human colon epithelial cell lines NCM460 and HT-29 cells were used to investigate the mechanisms of hPMSCs alleviating GVHD-induced intestinal oxidative damage.

RESULTS

hPMSCs reduced TNF-α concentrations and the number of CD3+TNF-α+ T-cells, which were negatively correlated with the expression of claudin-1, occludin, and ZO-1, through CD73 in the colon tissue of GVHD mice. Meanwhile, hPMSCs reduced the mean fluorescence intensity (MFI) of reactive oxygen species (ROS) and the concentration of malondialdehyde (MDA), promoted superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities, as well as claudin-1, occludin, and ZO-1 expression, in colonic epithelial cells of GVHD mice and TNF-α-stimulated cells via CD73. Moreover, hPMSCs upregulated adenosine (ADO) concentrations in GVHD mice and TNF-α-stimulated cells and mitigated the loss of tight junction proteins via the CD73/ADO/ADO receptors. Further analysis showed that hPMSCs diminished Fyn expression and enhanced Nrf2, GCLC, and HO-1 expression in both TNF-α-stimulated cells and colonic epithelial cells of GVHD mice by activating PI3K/Akt/GSK-3β pathway.

CONCLUSIONS

The results suggested that hPMSC-mediated redox metabolism balance and promoted tight junction protein expression were achieved via CD73/ADO/PI3K/Akt/GSK-3β/Fyn/Nrf2 axis, by which alleviating intestinal oxidative injury in GVHD mice.

Metabolic heterogeneity in tumor microenvironment - A novel landmark for immunotherapy

The surrounding non-cancer cells and tumor cells that make up the tumor microenvironment (TME) have various metabolic rhythms. TME metabolic heterogeneity is influenced by the intricate network of metabolic control within and between cells. DNA, protein, transport, and microbial levels are important regulators of TME metabolic homeostasis. The effectiveness of immunotherapy is also closely correlated with alterations in TME metabolism. The response of a tumor patient to immunotherapy is influenced by a variety of variables, including intracellular metabolic reprogramming, metabolic interaction between cells, ecological changes within and between tumors, and general dietary preferences. Although immunotherapy and targeted therapy have made great strides, their use in the accurate identification and treatment of tumors still has several limitations. The function of TME metabolic heterogeneity in tumor immunotherapy is summarized in this article. It focuses on how metabolic heterogeneity develops and is regulated as a tumor progresses, the precise molecular mechanisms and potential clinical significance of imbalances in intracellular metabolic homeostasis and intercellular metabolic coupling and interaction, as well as the benefits and drawbacks of targeted metabolism used in conjunction with immunotherapy. This offers insightful knowledge and important implications for individualized tumor patient diagnosis and treatment plans in the future.

Immunomodulatory properties of mesenchymal stromal/stem cells: The link with metabolism

BACKGROUND

Mesenchymal stromal/stem cells (MSCs) are the most promising stem cells for the treatment of multiple inflammatory and immune diseases due to their easy acquisition and potent immuno-regulatory capacities. These immune functions mainly depend on the MSC secretion of soluble factors. Recent studies have shown that the metabolism of MSCs plays critical roles in immunomodulation, which not only provides energy and building blocks for macromolecule synthesis but is also involved in the signaling pathway regulation.

AIM OF REVIEW

A thorough understanding of metabolic regulation in MSC immunomodulatory properties can provide new sights to the enhancement of MSC-based therapy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

MSC immune regulation can be affected by cellular metabolism (glucose, adenosine triphosphate, lipid and amino acid metabolism), which further mediates MSC therapy efficiency in inflammatory and immune diseases. The enhancement of glycolysis of MSCs, such as signaling molecule activation, inflammatory cytokines priming, or environmental control can promote MSC immune functions and therapeutic potential. Besides glucose metabolism, inflammatory stimuli also alter the lipid molecular profile of MSCs, but the direct link with immunomodulatory properties remains to be further explored. Arginine metabolism, glutamine-glutamate metabolism and tryptophan-kynurenine via indoleamine 2,3-dioxygenase (IDO) metabolism all contribute to the immune regulation of MSCs. In addition to the metabolism dictating the MSC immune functions, MSCs also influence the metabolism of immune cells and thus determine their behaviors. However, more direct evidence of the metabolism in MSC immune abilities as well as the underlying mechanism requires to be uncovered.

LC-MS/MS-based serum proteomics reveals a distinctive signature in a rheumatoid arthritis mouse model after treatment with mesenchymal stem cells

Mesenchymal stem cells (MSCs) are known to be able to modulate immune responses, possess tissue-protective properties, and exhibit healing capacities with therapeutic potential for various diseases. The ability of MSCs to secrete various cytokines and growth factors provides new insights into autoimmune-diseases such as rheumatoid arthritis (RA). RA is a systemic autoimmune disease that affects the lining of synovial joints, causing stiffness, pain, inflammation, and joint erosion. In recent years, MSCs-based therapies have been widely proposed as promising therapies in the treatment of RA. However, the mechanism involved in disease-specific therapeutic effects of MSCs on RA remains unclear. To clarify the mechanism involved in effects of MSCs on RA, proteomic profiling was performed using an RA mouse model before and after treatment with MSCs. In this study, treatment efficacy of human umbilical cord blood-mesenchymal stem cells (hUCB-MSCs) was confirmed using a type II collagen-induced arthritis (CIA) mouse model. Results of measuring incidence rates of arthritis and clinical arthritis index (CAI) revealed that mice administrated with hUCB-MSCs had a significant reduction in arthritis severity. Proteins that might affect disease progression and therapeutic efficacy of hUCB-MSC were identified through LC-MS/MS analysis using serum samples. In addition, L-1000 analysis was performed for hUCB-MSC culture medium. To analysis data obtained from LC–MS/MS and L-1000, tools such as ExDEGA, MEV, and DAVID GO were used. Results showed that various factors secreted from hUCB-MSCs might play roles in therapeutic effects of MSCs on RA, with platelet activation possibly playing a pivotal role. Results of this study also suggest that SERPINE1 and THBS1 among substances secreted by hUCB-MSC might be key factors that can inhibit platelet activation. This paper is expected to improve our understanding of mechanisms involved in treatment effects of stem cells on rheumatoid arthritis.

Cartilaginous Metabolomics Reveals the Biochemical-Niche Fate Control of Bone Marrow-Derived Stem Cells

Joint disorders have become a global health issue with the growth of the aging population. Screening small active molecules targeting chondrogenic differentiation of bone marrow-derived stem cells (BMSCs) is of urgency. In this study, microfracture was employed to create a regenerative niche in rabbits (n = 9). Cartilage samples were collected four weeks post-surgery. Microfracture-caused morphological (n = 3) and metabolic (n = 6) changes were detected. Non-targeted metabolomic analysis revealed that there were 96 differentially expressed metabolites (DEMs) enriched in 70 pathways involved in anti-inflammation, lipid metabolism, signaling transduction, etc. Among the metabolites, docosapentaenoic acid 22n-3 (DPA) and ursodeoxycholic acid (UDCA) functionally facilitated cartilage defect healing, i.e., increasing the vitality and adaptation of the BMSCs, chondrogenic differentiation, and chondrocyte functionality. Our findings firstly reveal the differences in metabolomic activities between the normal and regenerated cartilages and provide a list of endogenous biomolecules potentially involved in the biochemical-niche fate control for chondrogenic differentiation of BMSCs. Ultimately, the biomolecules may serve as anti-aging supplements for chondrocyte renewal or as drug candidates for cartilage regenerative medicine.

CD73-Adenosinergic Axis Mediates the Protective Effect of Extracellular Vesicles Derived from Mesenchymal Stromal Cells on Ischemic Renal Damage in a Rat Model of Donation after Circulatory Death

We propose a new organ-conditioning strategy based on mesenchymal stromal cell (MSCs)/extracellular vesicle (EVs) delivery during hypothermic perfusion. MSCs/EVs marker CD73 is present on renal proximal tubular cells, and it protects against renal ischemia-reperfusion injury by converting adenosine monophosphate into adenosine (ADO). In this study, after checking if CD73-silenced EVs (EVsi) would impact in vitro tubular-cell proliferation, we perfused kidneys of a rat model of donation after circulatory death, with Belzer solution (BS) alone, BS supplemented with MSCs, EVs, or EVsi. The ADO and ATP levels were measured in the effluents and tissues. Global renal ischemic damage score (GRS), and tubular cell proliferation index (IPT) were evaluated in the tissue. EVsi did not induce cell proliferation in vitro. Ex vivo kidneys perfused with BS or BS + EVsi showed the worst GRS and higher effluent ADO levels than the MSC- and EV-perfused kidneys. In the EV-perfused kidneys, the tissue and effluent ATP levels and IPT were the highest, but not if CD73 was silenced. Tissue ATP content was positively correlated with tissue ADO content and negatively correlated with effluent ADO level in all groups. In conclusion, kidney conditioning with EVs protects against ischemic damage by activating the CD73/ADO system.

High Adenosine Extracellular Levels Induce Glioblastoma Aggressive Traits Modulating the Mesenchymal Stromal Cell Secretome

Glioblastoma is an aggressive, fast-growing brain tumor influenced by the composition of the tumor microenvironment (TME) in which mesenchymal stromal cell (MSCs) play a pivotal role. Adenosine (ADO), a purinergic signal molecule, can reach up to high micromolar concentrations in TME. The activity of specific adenosine receptor subtypes on glioma cells has been widely explored, as have the effects of MSCs on tumor progression. However, the effects of high levels of ADO on glioma aggressive traits are still unclear as is its role in cancer cells-MSC cross-talk. Herein, we first studied the role of extracellular Adenosine (ADO) on isolated human U343MG cells as a glioblastoma cellular model, finding that at high concentrations it was able to prompt the gene expression of Snail and ZEB1, which regulate the epithelial-mesenchymal transition (EMT) process, even if a complete transition was not reached. These effects were mediated by the induction of ERK1/2 phosphorylation. Additionally, ADO affected isolated bone marrow derived MSCs (BM-MSCs) by modifying the pattern of secreted inflammatory cytokines. Then, the conditioned medium (CM) of BM-MSCs stimulated with ADO and a co-culture system were used to investigate the role of extracellular ADO in GBM-MSC cross-talk. The CM promoted the increase of glioma motility and induced a partial phenotypic change of glioblastoma cells. These effects were maintained when U343MG cells and BM-MSCs were co-cultured. In conclusion, ADO may affect glioma biology directly and through the modulation of the paracrine factors released by MSCs overall promoting a more aggressive phenotype. These results point out the importance to deeply investigate the role of extracellular soluble factors in the glioma cross-talk with other cell types of the TME to better understand its pathological mechanisms.

Mesenchymal Stromal Cell Immunology for Efficient and Safe Treatment of Osteoarthritis

Mesenchymal stem cell (MSC) therapy represents a promising approach for the treatment of osteoarthritis (OA). MSCs can be readily isolated from multiple sources and expanded ex vivo for possible clinical application. They possess a unique immunological profile and regulatory machinery that underline their therapeutic effects. They also have the capacity to sense the changes within the tissue environment to display the adequate response. Indeed, there is a close interaction between MSCs and the host cells. Accordingly, MSCs demonstrate encouraging results for a variety of diseases including OA. However, their effectiveness needs to be improved. In this review, we selected to discuss the importance of the immunological features of MSCs, including the type of transplantation and the immune and blood compatibility. It is important to consider MSC immune evasive rather than immune privileged. We also highlighted some of the actions/mechanisms that are displayed during tissue healing including the response of MSCs to injury signals, their interaction with the immune system, and the impact of their lifespan. Finally, we briefly summarized the results of clinical studies reporting on the application of MSCs for the treatment of OA. The research field of MSCs is inspiring and innovative but requires more knowledge about the immunobiological properties of these cells. A better understanding of these features will be key for developing a safe and efficient medicinal product for clinical use in OA.