The Global Evolution and Impact of Systems Biology and Artificial Intelligence in Stem Cell Research and Therapeutics Development: A Scoping Review.

Advanced bioinformatics analysis, such as systems biology (SysBio) and artificial intelligence (AI) approaches, including machine learning (ML) and deep learning (DL), is increasingly present in stem cell (SC) research. An approximate timeline on these developments and their global impact is still lacking. We conducted a scoping review on the contribution of SysBio and AI analysis to SC research and therapy development based on literature published in PubMed between 2000 and 2024. We identified an 8-10-fold increase in research output related to all three search terms between 2000 and 2021, with a 10-fold increase in AI-related production since 2010. Use of SysBio and AI still predominates in preclinical basic research with increasing use in clinically oriented translational medicine since 2010. SysBio- and AI-related research was found all over the globe, with SysBio output led by the United States (US, n=1487), United Kingdom (UK, n=1094), Germany (n=355), The Netherlands (n=339), Russia (n=215), and France (n=149), while for AI-related research the US (n=853) and UK (n=258) take a strong lead, followed by Switzerland (n=69), The Netherlands (n=37), and Germany (n=19). The US and UK are most active in SCs publications related to AI/ML and AI/DL. The prominent use of SysBio in ESC research was recently overtaken by prominent use of AI in iPSC and MSC research. This study reveals the global evolution and growing intersection between AI, SysBio, and SC research over the past two decades, with substantial growth in all three fields and exponential increases in AI-related research in the past decade.

Excess glucose alone depress young mesenchymal stromal/stem cell osteogenesis and mitochondria activity within hours/days via NAD+/SIRT1 axis.

BACKGROUND: The impact of global overconsumption of simple sugars on bone health, which peaks in adolescence/early adulthood and correlates with osteoporosis (OP) and fracture risk decades, is unclear. Mesenchymal stromal/stem cells (MSCs) are the progenitors of osteoblasts/bone-forming cells, and known to decrease their osteogenic differentiation capacity with age. Alarmingly, while there is correlative evidence that adolescents consuming greatest amounts of simple sugars have the lowest bone mass, there is no mechanistic understanding on the causality of this correlation. METHODS: Bioinformatics analyses for energetics pathways involved during MSC differentiation using human cell information was performed. In vitro dissection of normal versus high glucose (HG) conditions on osteo-/adipo-lineage commitment and mitochondrial function was assessed using multi-sources of non-senescent human and murine MSCs; for in vivo validation, young mice was fed normal or HG-added water with subsequent analyses of bone marrow CD45- MSCs. RESULTS: Bioinformatics analyses revealed mitochondrial and glucose-related metabolic pathways as integral to MSC osteo-/adipo-lineage commitment. Functionally, in vitro HG alone without differentiation induction decreased both MSC mitochondrial activity and osteogenesis while enhancing adipogenesis by 8 h' time due to depletion of nicotinamide adenine dinucleotide (NAD+), a vital mitochondrial co-enzyme and co-factor to Sirtuin (SIRT) 1, a longevity gene also involved in osteogenesis. In vivo, HG intake in young mice depleted MSC NAD+, with oral NAD+ precursor supplementation rapidly reversing both mitochondrial decline and osteo-/adipo-commitment in a SIRT1-dependent fashion within 1 ~ 5 days. CONCLUSIONS: We found a surprisingly rapid impact of excessive glucose, a single dietary factor, on MSC SIRT1 function and osteogenesis in youthful settings, and the crucial role of NAD+-a single molecule-on both MSC mitochondrial function and lineage commitment. These findings have strong implications on future global OP and disability risks in light of current worldwide overconsumption of simple sugars.

Residual protein analysis by SDS-PAGE in clinically manufactured BM-MSC products.

Residual substances that are considered hazardous to the recipient must be removed from final cellular therapeutic products manufactured for clinical purposes. In doing so, quality rules determined by competent authorities (CAs) for the clinical use of tissue- and cell-based products can be met. In our study, we carried out residual substance analyses, and purity determination studies of trypsin and trypsin inhibitor in clinically manufactured bone marrow-derived mesenchymal stromal/stem cell products, using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method. Despite being a semiquantitative method, SDS-PAGE has several benefits over other methods for protein analysis, such as simplicity, convenience of use, and affordability. Due to its convenience and adaptability, SDS-PAGE is still a commonly used method in many laboratories, despite its limits in dynamic range and quantitative precision. Our goal in this work was to show that SDS-PAGE may be used effectively for protein measurement, especially where practicality and affordability are the major factors. The results of our study suggest a validated method to guide tissue and cell manufacturing sites for making use of an agreeable, accessible, and cost-effective method for residual substance analyses in clinically manufactured cellular therapies.

Isolation of Human Adipose-Derived Stromal/Stem Cells from Lipoaspirates.

Adipose tissue is an abundant and accessible source of stem cells with multipotent properties suitable for tissue engineering and regenerative medical applications. Adipose-derived stromal/stem cells (ASCs) have been widely used in tissue engineering and cell therapy. In addition, the clinical application of ASCs in the treatment of inflammation and injury has been proven a success. Here, we describe methods from our own laboratory and the literature for the isolation and expansion of Adipose-derived stromal/stem cells (ASCs). We present a large-scale procedure suitable for processing >100 mL volumes of lipoaspirate tissue specimens by collagenase digestion, a related procedure suitable for processing adipose tissue aspirates without digestion, and a procedure suitable for intact human adipose tissue, such as buccal fat pads in the maxillofacial region.

Isolation of Murine Adipose-Derived Stromal/Stem Cells Using an Explant Culture Method.

Adipose tissue provides a valuable cell source for tissue engineering, regenerative medicine, and adipose tissue biology studies. The most widely used adipose-derived stromal/stem cells (ASCs) isolation protocol involves enzymatic digestion with collagenase. However, the yield of the method often proves to be poor if not impossible for collection of sufficient stromal vascular fraction (SVF) for expansion when the sample size is small, for instance when only newborn mice are available for cell culture. Here, we describe an efficient protocol for the isolation and expansion of ASCs using explant culture as an alternative. Briefly, adipose tissue was minced after removing excess liquid. Then, the minced tissue was placed in culture dishes or flasks. The cells will migrate out of tissue and adhere to the culture surface after one or more days.

The Decellularized Cell-Derived Extracellular Matrix Enhances the Paracrine Function of Human Mesenchymal Stromal/Stem Cells.

The mesenchymal stromal/stem cells (MSCs) are known to secrete pleiotropic paracrine factors, contributing to tissue regeneration. This unique ability makes MSCs promising therapeutic tools for many diseases, including even those that were previously untreatable. Thus, the development of preconditioning approaches aimed at enhancing the paracrine function of MSCs attracts great interest. In the present work, we studied how the extracellular matrix, the essential part of the native tissue microenvironment, affects the secretory capacity of MSCs of various origins. The MSC-derived decellularized extracellular matrix (dECM), used as the cell culture substrate, triggered strong upregulation of FGF-2, MMP-1, HGF, GRO-α, GRO-ß, CXCL-5, CXCL-6, IL-6, IL-8, G-CSF and MCP-1. Functional in vitro tests revealed that conditioned media derived from MSCs cultured on dECM significantly improved 3T3 fibroblast and HaCaT keratinocyte scratch wound healing, stimulated THP-1 monocyte migration and promoted capillary-like HUVEC-based tube formation compared to conditioned media from MSCs grown on plastic. In addition, we found that FAK inhibition promoted dECM-induced upregulation of paracrine factors, suggesting that this kinase participates in the MSCs' paracrine response to dECM. Together, these findings demonstrate that dECM provides cues that considerably enhance the secretory function of MSCs. Thus, dECM usage as a cell culture substrate alone or in combination with a FAK inhibitor may be viewed as a novel MSC preconditioning technique.

Differentiation of Human Induced Pluripotent Stem Cells (iPSCs)-derived Mesenchymal Progenitors into Chondrocytes.

Induced pluripotent stem cells (iPSCs) generated from human sources are valuable tools for studying skeletal development and diseases, as well as for potential use in regenerative medicine for skeletal tissues such as articular cartilage. To successfully differentiate human iPSCs into functional chondrocytes, it is essential to establish efficient and reproducible strategies that closely mimic the physiological chondrogenic differentiation process. Here, we describe a simple and efficient protocol for differentiation of human iPSCs into chondrocytes via generation of an intermediate population of mesenchymal progenitors. These methodologies include step-by-step procedures for mesenchymal derivation, induction of chondrogenic differentiation, and evaluation of the chondrogenic marker gene expression. In this protocol, we describe the detailed procedure for successful derivation of mesenchymal progenitor population from human iPSCs, which are then differentiated into chondrocytes using high-density culture conditions by stimulating with bone morphogenetic protein-2 (BMP-2) or transforming growth factor beta-3 (TGFß-3). The differentiated iPSCs exhibit temporal expression of cartilage genes and accumulation of a cartilaginous extracellular matrix in vitro, indicating successful chondrogenic differentiation. These detailed methodologies help effective differentiation of human iPSCs into the chondrogenic lineage to obtain functional chondrocytes, which hold great promise for modeling skeletal development and disease, as well as for potential use in regenerative medicine for cell-based therapy for cartilage regeneration. Key features • Differentiation of human iPSCs into chondrocytes using 3D culture methods. • Uses mesenchymal progenitors as an intermediate for differentiation into chondrocytes.

Regenerative potential of mesenchymal stromal cells in wound healing: unveiling the influence of normoxic and hypoxic environments.

The innate and adaptive immune systems rely on the skin for various purposes, serving as the primary defense against harmful environmental elements. However, skin lesions may lead to undesirable consequences such as scarring, accelerated skin aging, functional impairment, and psychological effects over time. The rising popularity of mesenchymal stromal cells (MSCs) for skin wound treatment is due to their potential as a promising therapeutic option. MSCs offer advantages in terms of differentiation capacity, accessibility, low immunogenicity, and their central role in natural wound-healing processes. To accelerate the healing process, MSCs promote cell migration, angiogenesis, epithelialization, and granulation tissue development. Oxygen plays a critical role in the formation and expansion of mammalian cells. The term "normoxia" refers to the usual oxygen levels, defined at 20.21 percent oxygen (160 mm of mercury), while "hypoxia" denotes oxygen levels of 2.91 percent or less. Notably, the ambient O2 content (20%) in the lab significantly differs from the 2%-9% O2 concentration in their natural habitat. Oxygen regulation of hypoxia-inducible factor-1 (HIF-1) mediated expression of multiple genes plays a crucial role in sustaining stem cell destiny concerning proliferation and differentiation. This study aims to elucidate the impact of normoxia and hypoxia on MSC biology and draw comparisons between the two. The findings suggest that expanding MSC-based regenerative treatments in a hypoxic environment can enhance their growth kinetics, genetic stability, and expression of chemokine receptors, ultimately increasing their effectiveness.

Effects of Atrazine exposure on human bone marrow-derived mesenchymal stromal cells assessed by combinatorial assay matrix.

Introduction: Mesenchymal Stromal/Stem cells (MSCs) are an essential component of the regenerative and immunoregulatory stem cell compartment of the human body and thus of major importance in human physiology. The MSCs elicit their beneficial properties through a multitude of complementary mechanisms, which makes it challenging to assess their phenotype and function in environmental toxicity screening. We here employed the novel combinatorial assays matrix approach/technology to profile the MSC response to the herbicide Atrazine, which is a common environmental xenobiotic, that is in widespread agricultural use in the US and other countries, but banned in the EU. Our here presented approach is representative for screening the impact of environmental xenobiotics and toxins on MSCs as an essential representative component of human physiology and well-being. Methods: We here employed the combinatorial assay matrix approach, including a panel of well standardized assays, such as flow cytometry, multiplex secretome analysis, and metabolic assays, to define the phenotype and functionality of human-donor-derived primary MSCs exposed to the representative xenobiotic Atrazine. This assay matrix approach is now also endorsed for characterization of cell therapies by leading regulatory agencies, such as FDA and EMA. Results: Our results show that the exposure to Atrazine modulates the metabolic activity, size, and granularity of MSCs in a dose and time dependent manner. Intriguingly, Atrazine exposure leads to a broad modulation of the MSCs secretome (both upregulation and downmodulation of certain factors) with the identification of Interleukin-8 as the topmost upregulated representative secretory molecule. Interestingly, Atrazine attenuates IFNγ-induced upregulation of MHC-class-II, but not MHC-class-I, and early phosphorylation signals on MSCs. Furthermore, Atrazine exposure attenuates IFNγ responsive secretome of MSCs. Mechanistic knockdown analysis identified that the Atrazine-induced effector molecule Interleukin-8 affects only certain but not all the related angiogenic secretome of MSCs. Discussion: The here described Combinatorial Assay Matrix Technology identified that Atrazine affects both the innate/resting and cytokine-induced/stimulated assay matrix functionality of human MSCs, as identified through the modulation of selective, but not all effector molecules, thus vouching for the great usefulness of this approach to study the impact of xenobiotics on this important human cellular subset involved in the regenerative healing responses in humans.

Systematic review and meta-analysis of cell therapy for COVID-19: global clinical trial landscape, published safety/efficacy outcomes, cell product manufacturing and clinical delivery.

During the pandemic of severe respiratory distress syndrome coronavirus 2 (SARS-CoV2), many novel therapeutic modalities to treat Coronavirus 2019 induced disease (COVID-19) were explored. This study summarizes 195 clinical trials of advanced cell therapies targeting COVID-19 that were registered over the two years between January 2020 to December 2021. In addition, this work also analyzed the cell manufacturing and clinical delivery experience of 26 trials that published their outcomes by July 2022. Our demographic analysis found the highest number of cell therapy trials for COVID-19 was in United States, China, and Iran (N=53, 43, and 19, respectively), with the highest number per capita in Israel, Spain, Iran, Australia, and Sweden (N=0.641, 0.232, 0,223, 0.194, and 0.192 trials per million inhabitants). The leading cell types were multipotent mesenchymal stromal/stem cells (MSCs), natural killer (NK) cells, and mononuclear cells (MNCs), accounting for 72%, 9%, and 6% of the studies, respectively. There were 24 published clinical trials that reported on infusions of MSCs. A pooled analysis of these MSC studies found that MSCs provide a relative risk reduction for all-cause COVID-19 mortality of RR=0.63 (95% CI 0.46 to 0.85). This result corroborates previously published smaller meta-analyses, which suggested that MSC therapy demonstrated a clinical benefit for COVID-19 patients. The sources of the MSCs used in these studies and their manufacturing and clinical delivery methods were remarkably heterogeneous, with some predominance of perinatal tissue-derived products. Our results highlight the important role that cell therapy products may play as an adjunct therapy in the management of COVID-19 and its related complications, as well as the importance of controlling key manufacturing parameters to ensure comparability between studies. Thus, we support ongoing calls for a global registry of clinical studies with MSC products that could better link cell product manufacturing and delivery methods to clinical outcomes. Although advanced cell therapies may provide an important adjunct treatment for patients affected by COVID-19 in the near future, preventing pathology through vaccination still remains the best protection to date. We conducted a systematic review and meta-analysis of advanced cell therapy clinical trials as potential novel treatment for COVID-19 (resulting from SARS-CoV-2 coronavirus infection), including analysis of the global clinical trial landscape, published safety/efficacy outcomes (RR/OR), and details on cell product manufacturing and clinical delivery. This study had a 2-year observation interval from start of January 2020 to end of December 2021, including a follow-up period until end of July to identify published outcomes, which covers the most vivid period of clinical trial activity, and is also the longest observation period studied until today. In total, we identified 195 registered advanced cell therapy studies for COVID-19, employing 204 individual cell products. Leading registered trial activity was attributed to the USA, China, and Iran. Through the end of July 2022, 26 clinical trials were published, with 24 out of 26 articles employing intravenous infusions (IV) of mesenchymal stromal/stem cell (MSC) products. Most of the published trials were attributed to China and Iran. The cumulative results from the 24 published studies employing infusions of MSCs indicated an improved survival (RR=0.63 with 95% Confidence Interval 0.46 to 0.85). Our study is the most comprehensive systematic review and meta-analysis on cell therapy trials for COVID-19 conducted to date, clearly identifying the USA, China, and Iran as leading advanced cell therapy trial countries for COVID-19, with further strong contributions from Israel, Spain, Australia and Sweden. Although advanced cell therapies may provide an important adjunct treatment for patients affected by COVID-19 in the future, preventing pathology through vaccination remains the best protection.

Immunological priming of mesenchymal stromal/stem cells and their extracellular vesicles augments their therapeutic benefits in experimental graft-versus-host disease via engagement of PD-1 ligands.

Mesenchymal stromal cells (MSCs) and their extracellular vesicles (EVs) exert profound anti-inflammatory and regenerative effects in inflammation and tissue damage, which makes them an attractive tool for cellular therapies. In this study we have assessed the inducible immunoregulatory properties of MSCs and their EVs upon stimulation with different combinations of cytokines. First, we found that MSCs primed with IFN-γ, TNF-α and IL-1ß, upregulate the expression of PD-1 ligands, as crucial mediators of their immunomodulatory activity. Further, primed MSCs and MSC-EVs, compared to unstimulated MSCs and MSC-EVs, had increased immunosuppressive effects on activated T cells and mediated an enhanced induction of regulatory T cells, in a PD-1 dependent manner. Importantly, EVs derived from primed MSCs reduced the clinical score and prolonged the survival of mice in a model of graft-versus-host disease. These effects could be reversed in vitro and in vivo by adding neutralizing antibodies directed against PD-L1 and PD-L2 to both, MSCs and their EVs. In conclusion, our data reveal a priming strategy that potentiates the immunoregulatory function of MSCs and their EVs. This concept also provides new opportunities to improve the clinical applicability and efficiency of cellular or EV-based therapeutic MSC products.

Easy-to-Assembly System for Decellularization and Recellularization of Liver Grafts in a Bioreactor.

Decellularization of organs creates an acellular scaffold, ideal for being repopulated by cells. In this work, a low-cost perfusion system was created to be used in the process of liver decellularization and as a bioreactor after recellularization. It consists of a glass chamber to house the organ coupled to a peristaltic pump to promote liquid flow through the organ vascular tree. The rats' liver decellularization was made with a solution of sodium dodecyl sulfate. The recellularization was made with 108 mesenchymal stromal/stem cells and cultivated for seven days. The decellularized matrices showed an absence of DNA while preserving the collagen and glycosaminoglycans quantities, confirming the efficiency of the process. The functional analyses showed a rise in lactate dehydrogenase levels occurring in the first days of the cultivation, suggesting that there is cell death in this period, which stabilized on the seventh day. Histological analysis showed conservation of the collagen web and some groups of cells next to the vessels. It was possible to establish a system for decellularization and a bioreactor to use for the recellularization method. It is easy to assemble, can be ready to use in little time and be easily sterilized.

Clinical implications of differential functional capacity between tissue-specific human mesenchymal stromal/stem cells.

Over the past two decades, there has been an explosion in the numbers of clinical trials using mesenchymal stem cells (MSCs). While the safety profile of MSC therapy has been excellent, therapeutic success has not been as robust as expected. In addition to variabilities inherent in all live-cell products because of donor-specific differences and manufacturing practices, MSCs may have an additional layer of complexity due to the availability of many tissues/organ sources for isolation. Since first isolation from the bone marrow (BM) over 50 years ago, human MSCs have been robustly found in multiple tissues/organs. The increased variety of MSC sources is reflected in clinical trials: while BMMSCs was used in nearly all trials prior to 2008, they are used in less than 50% of clinical trials in recent years. While the majority of single-source MSC preclinical data accumulated over the past several decades do reveal biological differences between tissue-specific sources of MSCs, studies directly comparing different MSC sources are relatively rare. In this Review, we summarise these past findings and also specifically focus on studies comparing MSCs isolated from the most commonly utilised sources of BM, adipose tissue and post-partum discarded extraembryonic tissue. The MSC functions discussed here include paraxial mesodermal trilineage differentiation capacity, and also other well-studied and translationally relevant MSC functions of haematopoietic support, immunomodulation and paracrine capacities. Finally, we will discuss the implications of tissue-specific MSC functional differences on future research avenues, manufacturing practices, as well as clinical implementation.

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.

Immunogenicity of mesenchymal stromal/stem cells.

Mesenchymal stromal/stem cells (MSCs) possess the ability to self-renew and differentiate into other cell types. Because of their anti-inflammatory and immunomodulatory abilities, as well as their more ready availability compared to other stem cell sources, MSCs hold great promise for the treatment of many diseases, such as haematological defects, acute respiratory distress syndrome, autoimmunity, cardiovascular diseases, etc. However, immune rejection remains an important problem. MSCs are considered to have low immunogenicity, but they do not have full immunological privilege. This review analyzes and discusses the safety of MSCs from the perspective of their immunogenicity, with the aim of providing a reference for future research and clinical application.

Impact of Cryopreservation and Freeze-Thawing on Therapeutic Properties of Mesenchymal Stromal/Stem Cells and Other Common Cellular Therapeutics.

Purpose of Review: Cryopreservation and its associated freezing and thawing procedures-short "freeze-thawing"-are among the final steps in economically viable manufacturing and clinical application of diverse cellular therapeutics. Translation from preclinical proof-of-concept studies to larger clinical trials has indicated that these processes may potentially present an Achilles heel to optimal cell product safety and particularly efficacy in clinical trials and routine use. Recent Findings: We review the current state of the literature on how cryopreservation of cellular therapies has evolved and how the application of this technique to different cell types is interlinked with their ability to engraft and function upon transfer in vivo, in particular for hematopoietic stem and progenitor cells (HSPCs), their progeny, and therapeutic cell products derived thereof. We also discuss pros and cons how this may differ for non-hematopoietic mesenchymal stromal/stem cell (MSC) therapeutics. We present different avenues that may be crucial for cell therapy optimization, both, for hematopoietic (e.g., effector, regulatory, and chimeric antigen receptor (CAR)-modified T and NK cell based products) and for non-hematopoietic products, such as MSCs and induced pluripotent stem cells (iPSCs), to achieve optimal viability, recovery, effective cell dose, and functionality of the cryorecovered cells. Summary: Targeted research into optimizing the cryopreservation and freeze-thawing routines and the adjunct manufacturing process design may provide crucial advantages to increase both the safety and efficacy of cellular therapeutics in clinical use and to enable effective market deployment strategies to become economically viable and sustainable medicines.

Improved MSC Minimal Criteria to Maximize Patient Safety: A Call to Embrace Tissue Factor and Hemocompatibility Assessment of MSC Products.

The number of mesenchymal stromal/stem cell (MSC) therapeutics and types of clinical applications have greatly diversified during the past decade, including rapid growth of poorly regulated "Stem Cell Clinics" offering diverse "Unproven Stem Cell Interventions." This product diversification necessitates a critical evaluation of the reliance on the 2006 MSC minimal criteria to not only define MSC identity but characterize MSC suitability for intravascular administration. While high-quality MSC therapeutics have been safely administered intravascularly in well-controlled clinical trials, repeated case reports of mild-to-more-severe adverse events have been reported. These are most commonly related to thromboembolic complications upon infusion of highly procoagulant tissue factor (TF/CD142)-expressing MSC products. As TF/CD142 expression varies widely depending on the source and manufacturing process of the MSC product, additional clinical cell product characterization and guidelines are needed to ensure the safe use of MSC products. To minimize risk to patients receiving MSC therapy, we here propose to supplement the minimal criteria used for characterization of MSCs, to include criteria that assess the suitability of MSC products for intravascular use. If cell products are intended for intravascular delivery, which is true for half of all clinical applications involving MSCs, the effects of MSC on coagulation and hemocompatibility should be assessed and expression of TF/CD142 should be included as a phenotypic safety marker. This adjunct criterion will ensure both the identity of the MSCs as well as the safety of the MSCs has been vetted prior to intravascular delivery of MSC products.

Fast assay to predict multipotent mesenchymal stromal cell replicative senescence dynamics.

The major obstacle to the application of mesenchymal stromal cells (MSCs) in regenerative medicine is the expansion of the donor-derived cells in vitro to obtain high cell numbers in the shortest possible time. However, MSCs gradually undergo replicative senescence after a variable number of divisions that reduce their therapeutic efficacy, which needs to be determined before administration. The authors developed a fast and simple evaluation assay testing two senescence inducers, mitoxantrone (Mxt) and trichostatin A (TSA), to predict the onset of spontaneous replicative senescence of adipose-derived mesenchymal stromal cells (ASCs) and have confirmed the correlation between induced senescence and spontaneous replicative senescence in the assay using Mxt. This protocol facilitates the standardization of therapeutic ASCs and MSCs from other origins before application.

Mesenchymal Stromal Cells: a Possible Reservoir for HIV-1?

The introduction of antiretroviral therapy (ART) and highly active antiretroviral therapy (HAART) has transformed human immunodeficiency virus (HIV)-1 into a chronic, well-managed disease. However, these therapies do not eliminate all infected cells from the body despite suppressing viral load. Viral rebound is largely due to the presence of cellular reservoirs which support long-term persistence of HIV-1. A thorough understanding of the HIV-1 reservoir will facilitate the development of new strategies leading to its detection, reduction, and elimination, ultimately leading to curative therapies for HIV-1. Although immune cells derived from lymphoid and myeloid progenitors have been thoroughly studied as HIV-1 reservoirs, few studies have examined whether mesenchymal stromal/stem cells (MSCs) can assume this function. In this review, we evaluate published studies which have assessed whether MSCs contribute to the HIV-1 reservoir. MSCs have been found to express the receptors and co-receptors required for HIV-1 entry, albeit at levels of expression and receptor localisation that vary considerably between studies. Exposure to HIV-1 and HIV-1 proteins alters MSC properties in vitro, including their proliferation capacity and differentiation potential. However, in vitro and in vivo experiments investigating whether MSCs can become infected with and harbour latent integrated proviral DNA are lacking. In conclusion, MSCs appear to have the potential to contribute to the HIV-1 reservoir. However, further studies are needed using techniques such as those used to prove that cluster of differentiation (CD)4+ T cells constitute an HIV-1 reservoir before a reservoir function can definitively be ascribed to MSCs. MSCs may contribute to HIV-1 persistence in vivo in the vasculature, adipose tissue, and bone marrow by being a reservoir for latent HIV-1. To harbour latent HIV-1, MSCs must express HIV-1 entry markers, and show evidence of productive or latent HIV-1 infection. The effect of HIV-1 or HIV-1 proteins on MSC properties may also be indicative of HIV-1 infection.

Mesenchymal stem cells are prospective novel off-the-shelf wound management tools.

Chronic/non-healing cutaneous wounds pose a debilitating burden on patients and healthcare system. Presently, treatment modalities are rapidly shifting pace from conventional methods to advanced wound care involving cell-based therapies. Mesenchymal stem cells (MSCs) have come across as a prospective option due to its pleiotropic functions viz. non-immunogenicity, multipotency, multi-lineage plasticity and secretion of growth factors, cytokines, microRNAs (miRNA), exosomes, and microvesicles as part of their secretome for assisting wound healing. We outline the therapeutic role played by MSCs and its secretome in suppressing tissue inflammation, causing immunomodulation, aiding angiogenesis and assisting in scar-free wound healing. We further assess the mechanism of action by which MSCs contribute in manifesting tissue repair. The review flows ahead in exploring factors that influence healing behavior including effect of multiple donor sites, donor age and health status, tissue microenvironment, and in vitro expansion capability. Moving ahead, we overview the advancements achieved in extending the lifespan of cells upon implantation, influence of genetic modifications aimed at altering MSC cargo, and evaluating bioengineered matrix-assisted delivery methods toward faster healing in preclinical and clinical models. We also contribute toward highlighting the challenges faced in commercializing cell-based therapies as standard of care treatment regimens. Finally, we strongly advocate and highlight its application as a futuristic technology for revolutionizing tissue regeneration.