HLA-G and CD152 Expression Levels Encourage the Use of Umbilical Cord Tissue-Derived Mesenchymal Stromal Cells as an Alternative for Immunosuppressive Therapy

The issue of heterogeneity of MSC-based advanced therapy medicinal products-a review

Mesenchymal stromal stem cells (MSCs) possess a remarkable potential for numerous clinical applications due to their unique properties including self-renewal, immunomodulation, paracrine actions and multilineage differentiation. However, the translation of MSC-based Advanced Therapy Medicinal Products (ATMPs) into the clinic has frequently met with inconsistent outcomes. One of the suspected reasons for this issue is the inherent and extensive variability that exists among such ATMPs, which makes the interpretation of their clinical efficacy difficult to assess, as well as to compare the results of various studies. This variability stems from numerous reasons including differences in tissue sources, donor attributes, variances in manufacturing protocols, as well as modes of administration. MSCs can be isolated from various tissues including bone marrow, umbilical cord, adipose tissue and others, each with its unique phenotypic and functional characteristics. While MSCs from different sources do share common features, they also exhibit distinct gene expression profiles and functional properites. Donor-specific factors such as age, sex, body mass index, and underlying health conditions can influence MSC phenotype, morphology, differentiation potential and function. Moreover, variations in preparation of MSC products introduces additional heterogeneity as a result of cell culture media composition, presence or absence of added growth factors, use of different serum supplements and culturing techniques. Once MSC products are formulated, storage protocols play a pivotal role in its efficacy. Factors that affect cell viability include cell concentration, delivery solution and importantly, post-thawing protocols where applicable. Ensuing, differences in administration protocols can critically affect the distribution and functionallity of administered cells. As MSC-based therapies continue to advance through numerous clinical trials, implication of strategies to reduce product heterogeneity is imperative. Central to addressing these challenges is the need for precise prediction of clinical responses, which require well-defined MSC populations and harmonized assessment of their specific functions. By addressing these issues by meaningful approaches, such as, e.g., MSC pooling, the field can overcome barriers to advance towards more consistent and effective MSC-based therapies.

Adoptive cell therapy for solid tumors beyond CAR-T: Current challenges and emerging therapeutic advances

Adoptive cellular immunotherapy using immune cells expressing chimeric antigen receptors (CARs) is a highly specific anti-tumor immunotherapy that has shown promise in the treatment of hematological malignancies. However, there has been a slow progress toward the treatment of solid tumors owing to the complex tumor microenvironment that affects the localization and killing ability of the CAR cells. Solid tumors with a strong immunosuppressive microenvironment and complex vascular system are unaffected by CAR cell infiltration and attack. To improve their efficacy toward solid tumors, CAR cells have been modified and upgraded by "decorating" and "pruning". This review focuses on the structure and function of CARs, the immune cells that can be engineered by CARs and the transformation strategies to overcome solid tumors, with a view to broadening ideas for the better application of CAR cell therapy for the treatment of solid tumors.

Mesenchymal stromal cell derived extracellular vesicles as a therapeutic tool: immune regulation, MSC priming, and applications to SLE

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a dysfunction of the immune system. Mesenchymal stromal cell (MSCs) derived extracellular vesicles (EVs) are nanometer-sized particles carrying a diverse range of bioactive molecules, such as proteins, miRNAs, and lipids. Despite the methodological disparities, recent works on MSC-EVs have highlighted their broad immunosuppressive effect, thus driving forwards the potential of MSC-EVs in the treatment of chronic diseases. Nonetheless, their mechanism of action is still unclear, and better understanding is needed for clinical application. Therefore, we describe in this review the diverse range of bioactive molecules mediating their immunomodulatory effect, the techniques and possibilities for enhancing their immune activity, and finally the potential application to SLE.

Influence of type 2 diabetes and obesity on adipose mesenchymal stem/stromal cell immunoregulation

Type 2 diabetes (T2D), associated with obesity, represents a state of metabolic inflammation and oxidative stress leading to insulin resistance and progressive insulin deficiency. Adipose-derived stem cells (ASCs) are adult mesenchymal stem/stromal cells identified within the stromal vascular fraction of adipose tissue. These cells can regulate the immune system and possess anti-inflammatory properties. ASCs are a potential therapeutic modality for inflammatory diseases including T2D. Patient-derived (autologous) rather than allogeneic ASCs may be a relatively safer approach in clinical perspectives, to avoid occasional anti-donor immune responses. However, patient characteristics such as body mass index (BMI), inflammatory status, and disease duration and severity may limit the therapeutic utility of ASCs. The current review presents human ASC (hASC) immunoregulatory mechanisms with special emphasis on those related to T lymphocytes, hASC implications in T2D treatment, and the impact of T2D and obesity on hASC immunoregulatory potential. hASCs can modulate the proliferation, activation, and functions of diverse innate and adaptive immune cells via direct cell-to-cell contact and secretion of paracrine mediators and extracellular vesicles. Preclinical studies recommend the therapeutic potential of hASCs to improve inflammation and metabolic indices in a high-fat diet (HFD)-induced T2D disease model. Discordant data have been reported to unravel intact or detrimentally affected immunomodulatory functions of ASCs, isolated from patients with obesity and/or T2D patients, in vitro and in vivo. Numerous preconditioning strategies have been introduced to potentiate hASC immunomodulation; they are also discussed here as possible options to potentiate the immunoregulatory functions of hASCs isolated from patients with obesity and T2D.