The immunomodulatory potential of mesenchymal stromal cells (MSCs) and regulatory T cells (T‐reg) is well recognized by translational scientists in the field of regenerative medicine and cellular ...therapies. A wide range of preclinical studies as well as a limited number of human clinical trials of MSC therapies have not only shown promising safety and efficacy profiles but have also revealed changes in T‐reg frequency and function. However, the mechanisms underlying this potentially important observation are not well understood and, consequently, the optimal strategies for harnessing MSC/T‐reg cross‐talk remain elusive. Cell‐to‐cell contact, production of soluble factors, reprogramming of antigen presenting cells to tolerogenic phenotypes, and induction of extracellular vesicles (“exosomes”) have emerged as possible mechanisms by which MSCs produce an immune‐modulatory milieu for T‐reg expansion. Additionally, these two cell types have the potential to complement each other's immunoregulatory functions, and a combinatorial approach may exert synergistic effects for the treatment of immunological diseases. In this review, we critically assess recent translational research related to the outcomes and mechanistic basis of MSC effects on T‐reg and provide a perspective on the potential for this knowledge base to be further exploited for the treatment of autoimmune disorders and transplants.
Mesenchymal stromal cells (MSCs) promote regulatory T cell numbers and immune suppressive functions through mechanisms involving cell‐cell contact, production of soluble mediators, reprogramming of antigen presenting cells, and release of extracellular vesicles that likely represent important components of MSC therapeutic effects in immune/inflammatory diseases.
Mesenchymal stem (stromal) cells (MSCs) are multipotent cells with the ability to differentiate into several cell types, thus serving as a cell reservoir for regenerative medicine. Much of the ...current interest in therapeutic application of MSCs to various disease settings can be linked to their immunosuppressive and anti-inflammatory properties. One of the key mechanisms of MSC anti-inflammatory effects is the secretion of soluble factors with paracrine actions. Recently it has emerged that the paracrine functions of MSCs could, at least in part, be mediated by extracellular vesicles (EVs). EVs are predominantly released from the endosomal compartment and contain a cargo that includes miRNA, mRNA, and proteins from their cells of origin. Recent animal model-based studies suggest that EVs have significant potential as a novel alternative to whole cell therapies. Compared to their parent cells, EVs may have a superior safety profile and can be safely stored without losing function. In this article, we review current knowledge related to the potential use of MSC-derived EVs in various diseases and discuss the promising future for EVs as an alternative, cell-free therapy.
A little over 10 years ago, the therapeutic potential of mesenchymal stromal cells (MSCs) for the treatment of acute kidney injury (AKI) was becoming widely recognized. Since then, there has been ...further intensive study of this topic with a clear translational intent. Over the past decade, many more animal model studies have strengthened the evidence that systemically or locally delivered MSCs ameliorate renal injury in sterile and sepsis-associated AKI. Some of these preclinical studies have also provided a range of compelling new insights into the in vivo fate and mechanisms of action of MSCs in the setting of AKI and other inflammatory conditions. Coupled with increased knowledge of the functional roles of resident and infiltrating immune cell mediators in determining the severity and outcome of AKI, the progress made in the past decade would appear to have significantly strengthened the translational pathway for MSC-based therapies. In contrast, however, the extent of the clinical experience with MSC administration in human subjects with AKI or sepsis-associated AKI has been limited to a small number of early-phase clinical trials, which appear to demonstrate safety but have not thus far delivered a strong signal of efficacy. In this review, we summarize the most significant new developments in the field of MSC-based therapies as they relate to AKI and reflect on the key gaps in knowledge and technology that remain to be addressed for the true clinical potential of MSCs and, perhaps, other emerging cellular therapies to be realized.
Monocytes are a highly plastic innate immune cell population that displays significant heterogeneity within the circulation. Distinct patterns of surface marker expression have become accepted as a ...basis for distinguishing three monocyte subsets in humans. These phenotypic subsets, termed classical, intermediate and nonclassical, have also been demonstrated to differ in regard to their functional properties and disease associations when studied
and
. Nonetheless, for the intermediate monocyte subset in particular, functional experiments have yielded conflicting results and some studies point to further levels of heterogeneity. Developments in genetic sequencing technology have provided opportunities to more comprehensively explore the phenotypic and functional differences among conventionally-recognized immune cell subtypes as well as the potential to identify novel subpopulations. In this review, we summarize the transcriptomic evidence in support of the existence of three separate monocyte subsets. We also critically evaluate the insights into subset functional distinctions that have been garnered from monocyte gene expression analysis and the potential utility of such studies to unravel subset-specific functional changes which arise in disease states.
Impaired healing of cutaneous wounds and ulcers continues to have a major impact on the quality of life of millions of people. In recent years, the capacity for stem and progenitor cells to promote ...wound repair has been investigated with evidence that secreted factors are responsible for the observed therapeutic benefits. This review addresses current evidence in support of stem/progenitor cell-derived extracellular vesicles (EVs) as a regenerative therapy for acceleration of wound healing. Encouraging results for local or systemic administration of EVs have been reported in a range of clinically-relevant animal models of cutaneous wounds. Furthermore, a number of plausible mechanisms involving EV-mediated transfer of proteins and RNAs that trigger pro-repair pathways in target cells have been demonstrated experimentally. However, for successful clinical translation in the coming years, further emphasis on standardized experimental protocols, detailed methodological reporting and clear definition of EV-based therapeutic products will be required.
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Innate immune cells are key contributors to kidney inflammation and fibrosis. Infiltration of the renal parenchyma by innate immune cells is governed by multiple signalling pathways. Since the ...discovery of the chemokine fractalkine (CX3CL1) and its receptor, CX3CR1 over twenty years ago, a wealth of evidence has emerged linking CX3CL1-CX3CR1 signalling to renal pathologies in both acute and chronic kidney diseases (CKD). However, despite the extent of data indicating a pathogenic role for this pathway in kidney disease and its complications, no human trials of targeted therapeutic agents have been reported. Although acute autoimmune kidney disease is often successfully treated with immunomodulatory medications, there is a notable lack of treatment options for patients with progressive fibrotic CKD. In this article we revisit the CX3CL1-CX3CR1 axis and its functional roles. Furthermore we review the accumulating evidence that CX3CL1-CX3CR1 interactions mediate important events in the intra-renal pathophysiology of CKD progression, particularly
recruitment of innate immune cells into the kidney. We also consider the role that systemic activation of the CX3CL1-CX3CR1 axis in renal disease contributes to CKD-associated cardiovascular disease. Based on this evidence, we highlight the potential for therapies targeting CX3CL1 or CX3CR1 to benefit people living with CKD.
CKD is accompanied by abnormal inflammation, which contributes to progressive loss of functional renal tissue and accelerated cardiovascular disease. Although studies have documented that ...dysregulation of monocyte maturation and function is associated with CKD and its complications, it is not well characterized. This study reveals that a distinctive human monocyte subtype with high propensity for releasing proinflammatory mediators and activating endothelial cells is increased in adults with CKD compared with adults with high cardiovascular risk and normal kidney function. It also demonstrates that human monocyte adhesion to endothelial layers and responses to specific inflammatory migration signals are enhanced in CKD. These findings offer insights into the mechanisms of CKD-associated intravascular and localized inflammation and may suggest potential targets for therapeutic interventions.
Cardiovascular disease (CVD) in patients with CKD is associated with increased circulating intermediate monocytes (IMs). Dysregulation of monocyte maturation and function is associated with CKD and its complications, but it is incompletely characterized.
To explore monocyte repertoire abnormalities in CKD, we studied properties of monocyte subpopulations, including IM subpopulations distinguished by HLA-DR expression level, in individuals with or without CKD. Using flow cytometry, we profiled monocyte populations in blood samples from adults with CKD, healthy volunteers (HVs), and patient controls (PCs) with high CVD risk. Monocyte subpopulations were also derived from single-cell RNA-sequencing profiles of paired blood and biopsy samples from kidney transplant recipients. We quantified intracellular cytokine production, migration, and endothelial adhesion in ex vivo assays of PBMCs.
Of four predefined blood monocyte subpopulations, only HLA-DR hi IMs were increased in individuals with CKD compared with HVs and PCs. In HVs and patients with CKD, LPS-stimulated HLA-DR hi IMs isolated from blood produced higher amounts of TNF and IL-1 β than other monocyte populations. Single-cell analysis revealed four monocyte clusters common to blood and kidneys, including an HLA-DR hi IM-like cluster that was enriched in kidneys versus blood. Migration toward CCL5 and CX3CL1 and adhesion to primary endothelial cell layers were increased in monocyte subpopulations in individuals with CKD compared with HVs. Monocyte adhesion to endothelial cells was partly dependent on CX3CR1/CX3CL1 interaction.
CKD is associated with an increased number of a distinctive proinflammatory IM subpopulation and abnormalities of monocyte migration and endothelial adhesion. Dysregulated monocyte maturation and function may represent targetable factors contributing to accelerated CVD in CKD.
To simulate the cost-effectiveness of Mesenchymal Stromal Cell (MSC) therapy compared to sodium/glucose co-transporter 2 inhibitors (SGLT2i) or usual care (UC) in treating patients with Diabetic ...Kidney Disease (DKD).
This Markov-chain Monte Carlo model adopted a societal perspective and simulated 10,000 patients with DKD eligible for MSC therapy alongside UC using a lifetime horizon. This cohort was compared with an SGLT2i alongside UC arm and a UC only arm. Model input data were extracted from the literature. A threshold of $47,000 per quality-adjusted life year and a discount rate of 3% were used. The primary outcome measure was incremental net monetary benefit (INMB). Sensitivity analysis was conducted to examine: parameter uncertainty; threshold effects regarding MSC effectiveness and cost; and INMB according to patient age (71 vs 40 years), sex, and jurisdiction (UK, Italy and Ireland).
While MSC was more cost-effective than UC, both the UC and MSC arms were dominated by SLGT2i. Relative to SGLT2i, the INMB's for MSC and UC were -$4,158 and -$10,085 respectively indicating that SGLT2i, MSC and UC had a 64%, 34% and 1% probability of being cost-effective at the given threshold, respectively. This pattern was consistent across most scenarios; driven by the relatively low cost of SGLT2i and demonstrated class-effect in delaying kidney failure and all-cause mortality. When examining younger patients at baseline, SGLT2i was still the most cost-effective but MSC performed better against UC given the increased lifetime benefit from delaying progression to ESRD.
The evidence base regarding the effectiveness of MSC therapy continues to evolve. The potential for these therapies to reverse kidney damage would see large improvements in their cost-effectiveness as would targeting such therapies at younger patients and/or those for whom SGLT2i is contra-indicated.
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