Biology Of Mesenchymal Stromal Cells Research Articles

Irisin influences the in vitro differentiation of human mesenchymal stromal cells, promoting a tendency towardbeiging adipogenesis.

Mammals exhibit two distinct types of adipose depots: white adipose tissue (WAT)and brown adipose tissue (BAT).While WAT primarily functions as a site for energy storage, BAT serves as a thermogenic tissue that utilizes energy and glucose consumption to regulate core body temperature. Under specific stimuli such as exercise, cold exposure, and drug treatment, white adipocytes possess a remarkable ability to undergo transdifferentiation into brown-like cells known as beige adipocytes. This transformation process, known as the "browning of WAT," leads to the acquisition of new morphological and physiological characteristics by white adipocytes. We investigated the potential role of Irisin, a 12 kDa myokine that is secreted in mice and humans by skeletal muscle after physical activity, in inducing the browning process in mesenchymal stromal cells (MSCs). A subset of the MSCs possesses the remarkable capability to differentiate into different cell types such as adipocytes, osteocytes, and chondrocytes. Consequently, comprehending the effects of Irisin on MSC biology becomes a crucial factor in investigating antiobesity medications. In our study, the primary objective is to evaluate the impact of Irisin on various cell types engaged in distinct stages of the differentiation process, including stem cells, committed precursors, and preadipocytes. By analyzing the effects of Irisin on these specific cell populations, our aim is to gain a comprehensive understanding of its influence throughout the entire differentiation process, rather than solely concentrating on the final differentiated cells. This approach enables us to obtain insights into the broader effects of Irisin on the cellular dynamics and mechanisms involved in adipogenesis.

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.

The Role of Mesenchymal Stromal Cells in Tissue Repair and Fibrosis.

Significance: The present review covers an overview of the current understanding of biology of mesenchymal stromal cells (MSCs) and suggests an important role of their differential potential for clinical approaches associated with tissue repair and fibrosis. Recent Advances: Genetic lineage tracing technology has enabled the delineation of cellular hierarchies and examination of MSC cellular origins and myofibroblast sources. This technique has led to the characterization of perivascular MSC populations and suggests that pericytes might provide a local source of tissue-specific MSCs, which can differentiate into tissue-specific cells for tissue repair and fibrosis. Autologous adipose tissue MSCs led to the advance in tissue engineering for regeneration of damaged tissues. Critical Issues: Recent investigation has revealed that perivascular MSCs might be the origin of myofibroblasts during fibrosis development, and perivascular MSCs might be the major source of myofibroblasts in fibrogenic disease. Adipose tissue MSCs combined with cytokines and biomaterials are available in the treatment of soft tissue defect and skin wound healing. Future Directions: Further investigation of the roles of perivascular MSCs may enable new approaches in the treatment of fibrogenic disease; moreover, perivascular MSCs might have potential as an antifibrotic target for fibrogenic disease. Autologous adipose tissue MSCs combined with cytokines and biomaterials will be an alternative method for the treatment of soft tissue defect and skin wound healing.

Therapeutic Implications of Mesenchymal Stromal Cells and Their Extracellular Vesicles in Autoimmune Diseases: From Biology to Clinical Applications.

Mesenchymal stromal cells (MSCs) are perivascular multipotent stem cells originally identified in the bone marrow (BM) stroma and subsequently in virtually all vascularized tissues. Because of their ability to differentiate into various mesodermal lineages, their trophic properties, homing capacity, and immunomodulatory functions, MSCs have emerged as attractive candidates in tissue repair and treatment of autoimmune disorders. Accumulating evidence suggests that the beneficial effects of MSCs may be primarily mediated via a number of paracrine-acting soluble factors and extracellular vesicles (EVs). EVs are membrane-coated vesicles that are increasingly being acknowledged as playing a key role in intercellular communication via their capacity to carry and deliver their cargo, consisting of proteins, nucleic acids, and lipids to recipient cells. MSC-EVs recapitulate the functions of the cells they originate, including immunoregulatory effects but do not seem to be associated with the limitations and concerns of cell-based therapies, thereby emerging as an appealing alternative therapeutic option in immune-mediated disorders. In the present review, the biology of MSCs will be outlined and an overview of their immunomodulatory functions will be provided. In addition, current knowledge on the features of MSC-EVs and their immunoregulatory potential will be summarized. Finally, therapeutic applications of MSCs and MSC-EVs in autoimmune disorders will be discussed.

The Current Status of Mesenchymal Stromal Cells: Controversies, Unresolved Issues and Some Promising Solutions to Improve Their Therapeutic Efficacy.

Mesenchymal stromal cells (MSCs) currently constitute the most frequently used cell type in advanced therapies with different purposes, most of which are related with inflammatory processes. Although the therapeutic efficacy of these cells has been clearly demonstrated in different disease animal models and in numerous human phase I/II clinical trials, only very few phase III trials using MSCs have demonstrated the expected potential therapeutic benefit. On the other hand, diverse controversial issues on the biology and clinical applications of MSCs, including their specific phenotype, the requirement of an inflammatory environment to induce immunosuppression, the relevance of the cell dose and their administration schedule, the cell delivery route (intravascular/systemic vs. local cell delivery), and the selected cell product (i.e., use of autologous vs. allogeneic MSCs, freshly cultured vs. frozen and thawed MSCs, MSCs vs. MSC-derived extracellular vesicles, etc.) persist. In the current review article, we have addressed these issues with special emphasis in the new approaches to improve the properties and functional capabilities of MSCs after distinct cell bioengineering strategies.

Immune Reprogramming in Human Subjects after Extracorporeal Mesenchymal Stromal Cell Therapy

Background & Aim Mesenchymal stromal cells (MSCs) are a unique source of secreted factors that modulate an inflammatory response and enhance the repair of injured tissue. Sentien has created a novel delivery approach to enable sustained exposure to MSCs and their secreted factors, overcoming limits of cell transplantation/infusion while preserving the broad acting and dynamically responsive properties. Our lead product, SBI-101, contains allogeneic human MSCs inoculated into a hollow-fiber hemofilter, which promotes contact with patient blood via the semi-permeable membrane, while promoting MSC viability. SBI-101 is designed to restore balance to the immune system by reprograming the molecular and cellular components of blood in patients with severe organ injury. We are conducting a Phase I/II clinical study of SBI-101 in critically ill patients with Dialysis-Requiring Acute Kidney Injury (AKI-D). Methods, Results & Conclusion In the initial cohort analyzed, patients were randomized to receive SBI-101 (250 × 106 cells) or sham control up to 24 hours of treatment (n=4 per group). Over 200 exploratory biomarkers were measured to characterize the MSC response as well as the pharmacodynamic (PD) effects of SBI-101. Samples were collected for the measurement of immune cell populations, kidney injury biomarkers, and biomarkers of inflammation at pre dose, conclusion of treatment, days 1, 3, 7, 14, 21, and 28 post-treatment with SBI-101 or sham control. Data showed an MSC response that seems to be dynamic and specific to each patient. Trends in PD response were also observed. Inflammatory (anti- and pro-) markers, such as IL-10 and TNFa, consistent with MSC biology were shown to be modulated, suggestive of a shift from a pro- to anti- inflammatory state. In addition, innate and adaptive cellular immune changes were also observed, such as reduction in total monocytes. Finally, early markers of kidney injury (eg, KIM-1) were also seen to have effect sizes greater than one. Despite therapy being administered for a maximum of 24 hours, a durable effect was observed out to a week in some cases. While the study was not powered for significance, the results demonstrate a dynamic biological response from the MSCs with potentially beneficial effects in the immune system as well as in the kidney of these critically ill patients. Moreover, it supports the therapeutic hypothesis of SBI-101 as a potent immunotherapy.

The Phenotype and Functional Activity of Mesenchymal Stromal Cells in Pediatric Patients with Non-Malignant Hematological Diseases

As the biology of mesenchymal stromal cells (MSCs) in patients with non-malignant hematological diseases (NMHD) is poorly understood, in the current study we performed a basic characterization of the phenotype and functional activity of NMHD-MSCs. Bone marrow (BM) of patients with thalassemia major (TM) possessed a significantly higher number of nucleated cells (BM-MNCs)/mL BM than healthy donors (P < 0.0001), which however did not result in a higher number of colony forming units-fibroblast (CFU-F) per milliliter BM. In contrast, from 1 × 106 BM-MNCs of patients with sickle cell disease (SCD) were generated significantly more CFU-Fs than from TM-BM-MNCs (P < 0.013) and control group (P < 0.02). In addition, NMHD-MSCs expressed significantly lower levels of CD146 molecule, demonstrated an equal proliferation potential and differentiated along three lineages (osteoblasts, chondrocytes and adipocytes) as healthy donors’ MSCs, with exception of TM-MSCs which differentiated weakly in adipocytes. In contrast to other NMHD-MSCs and healthy donors’ MSCs, TM-MSCs demonstrated an impaired in vitro immunosuppressive potential, either. Noteworthy, the majority of the immunosuppressive effect of NMHD-MSCs was mediated through prostaglandin-E2 (PGE2), because indomethacin (an inhibitor of PGE2 synthesis) was able to significantly reverse this effect. Our results indicate therefore that NMHD-MSCs, except TM-MSCs, may be used as an autologous cell-based therapy for post-transplant complications such as graft failure, graft-versus-host disease (GvHD) and osteonecrosis.

Characterizing the effects of hypoxia on the metabolic profiles of mesenchymal stromal cells derived from three tissue sources using chemical isotope labeling liquid chromatography-mass spectrometry.

Microenvironmental factors such as oxygen concentration mediate key effects on the biology of mesenchymal stromal cells (MSCs). Herein, we performed an in-depth characterization of the metabolic behavior of MSCs derived from the placenta, umbilical cord, and adipose tissue (termed hPMSCs, UC-MSCs, and AD-MSCs, respectively) at physiological (hypoxic; 5% oxygen [O2]) and standardized (normoxic; 21% O2) O2 concentrations using chemical isotope labeling liquid chromatography-mass spectrometry. 12C- and 13C-isotope dansylation (Dns) labeling was used to analyze the amine/phenol submetabolome, and 2574 peak pairs or metabolites were detected and quantified, from which 52 metabolites were positively identified using a library of 275 Dns-metabolite standards; 2189 metabolites were putatively identified. Next, we identified six metabolites using the Dns library, as well as 14 hypoxic biomarkers from the human metabolome database out of 96 altered metabolites. Ultimately, metabolic pathway analyses were performed to evaluate the associated pathways. Based on pathways identified using the Kyoto Encyclopedia of Genes and Genomes, we identified significant changes in the metabolic profiles of MSCs in response to different O2 concentrations. These results collectively suggest that O2 concentration has the strongest influence on hPMSCs metabolic characteristics, and that 5% O2 promotes arginine and proline metabolism in hPMSCs and UC-MSCs but decreases gluconeogenesis (alanine-glucose) rates in hPMSCs and AD-MSCs. These changes indicate that MSCs derived from different sources exhibit distinct metabolic profiles.

Low-Level Radiofrequency Exposure Does Not Induce Changes in MSC Biology: An in vitro Study for the Prevention of NIR-Related Damage.

BackgroundThe ubiquitous diffusion of radiofrequency (RF) radiation across human living environments has attracted the attention of scientists. Though the adverse health effects of RF exposure remain debatable, it has been reported that the interaction of such radiation with biological macromolecular structures can be deleterious for stem cells, inducing impairment of their main functions involving self-renewal and differentiation.PurposeThe purpose of this study was to determine whether exposure to RF of 169 megahertz (MHz) that is part of very high radiofrequency (VHF) range 30–300 MHz, could cause damage to stem cells by inducing senescence and loss of regenerative and DNA repair capacity.MethodsThe study was conducted on mesenchymal stromal cells (MSCs) containing a subpopulation of stem cells. The MSCs were exposed to RFs of 169 MHz administered via an open meter 2G “Smart Meter” for different durations of time.ResultWe did not observe modifications in MSC biology as a result of the RF exposure conducted in our experiments.ConclusionWe concluded that MSCs are insensitive to RF radiation exposure at 169 MHz for various time intervals, including longer durations.

The biological response of mesenchymal stromal cells to thymol and carvacrol in comparison to their essential oil: An innovative new study

Mesenchymal stromal cells (MSCs) represent a progenitor cell population with several biological properties. MSCs are thus of therapeutic interest for cell-based therapy but great efforts are needed to enhance their efficiency and safety. Herbal remedies and in particular their bioactive molecules, are potential candidates for improving human health. The novelty and originality of this study is to develop an efficient cell-therapeutic product by combining MSCs with medicinal plant derived bioactive molecules. Thus, the impact of Essential Oil, Thymol and Carvacrol from Ptychotis verticillata on several BM-MSC biological features were studied. These compounds have shown positive effects on MSCs by preserving their morphology, sustaining their viability, promoting their proliferation, protecting them from cytotoxicity and oxidative stress. Accordingly, the combined administration of P. verticillata extract and MSCs may represent a new approach to enhance the therapeutic issue. Further investigations should greatly improve the manufacturing of these compounds as well as our understanding of the therapeutic effects of these bioactive molecules on the biology and functions of MSCs.

Use of adult mesenchymal stromal cells in tissue repair: impact of physical exercise.

Physical exercise (PE) has unquestionable beneficial effects on health, which likely extend into several organ-to-cell physiological processes. At the cell scale, endogenous mesenchymal stromal cells (MSCs) contribute to tissue repair, although their repair capacities may be insufficient in paucicellular or severely damaged tissues. For this reason, MSC transplantation holds great promise for tissue repair. With the goals of understanding if PE has beneficial effects on MSC biology and if PE potentiates their role in tissue repair, we reviewed literature reports regarding the effects of PE on MSC properties (specifically, proliferation, differentiation, and homing) and of a combination of PE and MSC transplantation on tissue repair (specifically neural, cartilage, and muscular tissues). Contradictory results have been reported; interpretation is complicated because various and different species, cell sources, and experimental protocols, specifically exercise programs, have been used. On the basis of these data, the effects of exercise on MSC proliferation and differentiation depend on exercise characteristics (type, intensity, duration, etc.) and on the characteristics of the tissue from which the MSCs were collected. For the in vitro studies, the level of strain (and other details of the mechanical stimulus), the time elapsed between the end of exposure to strain and MSC collection, the age of the donors, as well as the passage number at which the MSCs are evaluated also play a role. The combination of PE and MSC engraftment improves neural, cartilage, and muscular tissue recovery, but it is not clear whether the effects of MSCs and exercise are additive or synergistic.

Impairment of the Stromal SDF-1-Mediated Hematopoietic Support By GDF-11 in MDS Is Rescued By Luspatercept

Introduction:Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis due to genetic and functional abnormalities of hematopoietic stem and progenitor cells (HSPCs). Accumulating evidence now also points to the bone marrow microenvironment (BMME) as a key mediator of MDS pathophysiology.Increased levels of transforming growth factor beta (TGF-β) superfamily ligands, including growth differentiation factor 11 (GDF-11), in the bone marrow have been linked to ineffective erythropoiesis and activation of SMAD2/3 signalling in MDS. Luspatercept (ACE-536) is a novel recombinant fusion protein containing modified activin receptor type IIB linked to the fragment crystallisable (Fc) domain of human immunoglobulin G1 and is a first-in-class erythroid maturation agent. Luspatercept binds to selected TGF-β superfamily ligands, including GDF-11 and activin B, restoring late-stage erythropoiesis in MDS mice and patients. Whether luspatercept modulates the BMME is unknown.Aim:We investigated the potential impact of luspatercept on the biology of mesenchymal stromal cells (MSCs).Methods:MSCs from patients with either high-or low-risk MDS and age-matched healthy donors (HD) were treated with GDF-11 in the presence or absence of RAP-536, a homologue of luspatercept harboring the same activin receptor IIB domain. Subsequently, Smad signaling pathway activation was analyzed by Western blot. Moreover, MSC phenotype, stromal derived factor-1 (SDF-1/CXCL12) expression and secretion as well as the osteogenic differentiation potential were recorded. To study the impact on the hematopoietic support, MSCs were pre-treated for one week with GDF-11 ± RAP-536 before freshly isolated CD34+ HSPCs were seeded on the stromal layer. The colony formation (CAF-C) was analyzed weekly. After four weeks, the HSPCs were seeded in methylcellulose medium to perform a CFU-GEMM assay. Further, engraftment and migration potential of co-cultured HSPCs was analyzed in zebrafish embryos in vivo.Results:GDF-11/RAP-536 treatment did not impact viability, proliferation, and growth pattern of MSCs. The osteogenic differentiation was significantly improved by RAP-536 treatment which was shown by a 2.3-fold increase of ALP activity. GDF-11 induced Smad2/3 phosphorylation in MSCs which was inhibited by RAP-536 to about 50% of activity. The MSC phenotype characterized by the expression of CD73, CD90, CD105, CD146, CD29 and CD44 was not significantly influenced by RAP-536 treatment.Interestingly, the chemokine SDF-1 which plays an important role for the interaction and support of HSPCs was significantly up-regulated in MDS and HD MSCs by RAP-536 at both the mRNA (1.9-fold) and the protein level (2.1-fold; 313.0±35.0 vs. 649.7±76.8 pg/ml, *p< 0.05, n=3). This restored SDF-1 secretion of MSCs resulted in functional effects of HSPCs when co-cultured with MSCs. The number of CAF-C was significantly higher after two, three, and four weeks of HSPCs cultured on pre-treated MSC layers (12.0-fold / 3.4-fold / 1.75-fold). The phenotypical analysis of HSPCs demonstrated increased expression levels of CXCR4 in the adherent fraction. Addition of the CXCR4 antagonist AMD3100 blocked enhanced colony formation by RAP-536 confirming the previous observation on SDF-1 modulation. Clonal growth of CAF-C-derived HSPCs after four weeks of co-culture on un- or pre-treated MSC monolayers was analyzed in a secondary colony-forming cell assay (CFU) for an additional 14 days. The frequency of CFUs was increased in all lineages with significant differences in total colony numbers (15±5.8 vs. 35.8±14.7, *p< 0.05, n=6).These results were validated in vivo in a zebrafish model. HSPCs were co-cultured with GDF-11 and RAP-536 pre-treated MDS-MSCs for one week before injection into the zebrafish circulation. One and two days post-injection, a significantly higher cell proportion could be detected in the caudal hematopoietic (CHT) region as a result of RAP-536 pre-treatment (Fig.1).Conclusion:These data provide first evidence that RAP-536 has also the capacity to modulate MSCs which might contribute to the restoration of hematopoiesis in MDS. DisclosuresPlatzbecker:Celgene: Research Funding.

153 - Peculiar in vitro behaviour of autologous mesenchymal stromal cells from patients affected by progressive supranuclear palsy

Progressive Supranuclear palsy (PSP), a rare form of parkinsonism, is a sporadic and progressive neurodegenerative disease linked to the accumulation of Tau protein within neural cells (taupathies). No effective therapy is to date available for this no-option neurological disorder. Bone marrow (BM) mesenchymal stromal cells (MSC) have recently gained attention for therapeutic interventions due to their anti-inflammatory, anti-apoptotic and trophic properties, also for neurological disorders. In this context, our hospital-based GMP-approved facility provides autologous BMMSC manufactured as advanced therapy medicinal products (ATMPs) in a phase I clinical study (NCT01824121) with the aim to evaluate the safety of intra-arterial infusion of autologous BMMSC in patients with PSP. In connection with this project, we set up a parallel in vitro study with the aim to investigate MSC biology, and to disclose if any disease-linked defect occurs also in the non-neuronal mesenchymal compartment.

Advanced Glycation End-Products-, C-Type Lectin- and Cysteinyl/ Leukotriene-Receptors in Distinct Mesenchymal Stromal Cell Populations: Differential Transcriptional Profiles in Response to Inflammation.

Objective We aimed at characterizing the transcription profiles of immunological receptors associated with the biology of mesenchymal stromal cells (MSCs). Materials and Methods In this experimental study, quantitative real time-polymerase chain reaction (qRT- PCR) was performed to establish the transcription profiles of advanced glycation end-products (RAGE) receptor, C-type lectin receptors (CLRs, including DECTIN-1, DECTIN-2 and MINCLE), leukotriene B4 (LTB4) receptors (BLT1 and BLT2) and cysteinyl leukotrienes (CysLTs) receptors (CYSLTR1 and CYSLTR2) in distinct populations of MSCs grown under basic or inflammatory conditions. Results MSCs derived from adipose tissue (AT), foreskin (FSK), Wharton’s jelly (WJ) and bone marrow (BM) exhibited significantly different transcription levels for these genes. Interestingly, these transcription profiles substantially changed following exposure of MSCs to inflammatory signals. ConclusionCollectively, for the first time, our data highlights that MSCs depending on their tissue-source, present several relevant receptors potentially involved in the regulation of inflammatory and immunological responses. Understanding the roles of these receptors within MSCs immunobiology will incontestably improve the efficiency of utilization of MSCs during cell-based therapies.

Characterization and Immunomodulatory Effects of Canine Adipose Tissue- and Bone Marrow-Derived Mesenchymal Stromal Cells.

BackgroundMesenchymal stromal cells (MSC) hold promise for both cell replacement and immune modulation strategies owing to their progenitor and non-progenitor functions, respectively. Characterization of MSC from different sources is an important and necessary step before clinical use of these cells is widely adopted. Little is known about the biology and function of canine MSC compared to their mouse or human counterparts. This knowledge-gap impedes development of canine evidence-based MSC technologies.Hypothesis and ObjectivesWe hypothesized that canine adipose tissue (AT) and bone marrow (BM) MSC (derived from the same dogs) will have similar differentiation and immune modulatory profiles. Our objectives were to evaluate progenitor and non-progenitor functions as well as other characteristics of AT- and BM-MSC including 1) proliferation rate, 2) cell surface marker expression, 3) DNA methylation levels, 4) potential for trilineage differentiation towards osteogenic, adipogenic, and chondrogenic cell fates, and 5) immunomodulatory potency in vitro.Results1) AT-MSC proliferated at more than double the rate of BM-MSC (population doubling times in days) for passage (P) 2, AT: 1.69, BM: 3.81; P3, AT: 1.80, BM: 4.06; P4, AT: 2.37, BM: 5.34; P5, AT: 3.20, BM: 7.21). 2) Canine MSC, regardless of source, strongly expressed cell surface markers MHC I, CD29, CD44, and CD90, and were negative for MHC II and CD45. They also showed moderate expression of CD8 and CD73 and mild expression of CD14. Minor differences were found in expression of CD4 and CD34. 3) Global DNA methylation levels were significantly lower in BM-MSC compared to AT-MSC. 4) Little difference was found between AT- and BM-MSC in their potential for adipogenesis and osteogenesis. Chondrogenesis was poor to absent for both sources in spite of adding varying levels of bone-morphogenic protein to our standard transforming growth factor (TGF-β3)-based induction medium. 5) Immunomodulatory capacity was equal regardless of cell source when tested in mitogen-stimulated lymphocyte reactions. Priming of MSC with pro-inflammatory factors interferon-gamma and/or tumour necrosis factor did not increase the lymphocyte suppressive properties of the MSC compared to untreated MSC.Conclusions/SignificanceNo significant differences were found between AT- and BM-MSC with regard to their immunophenotype, progenitor, and non-progenitor functions. Both MSC populations showed strong adipogenic and osteogenic potential and poor chondrogenic potential. Both significantly suppressed stimulated peripheral blood mononuclear cells. The most significant differences found were the higher isolation success and proliferation rate of AT-MSC, which could be realized as notable benefits of their use over BM-MSC.

Genetic engineering of mesenchymal stromal cells for cancer therapy: turning partners in crime into Trojan horses.

Mesenchymal stromal cells (MSCs) are adult progenitor cells with a high migratory and differentiation potential, which influence a broad range of biological functions in almost every tissue of the body. Among other mechanisms, MSCs do so by the secretion of molecular cues, differentiation toward more specialized cell types, or influence on the immune system. Expanding tumors also depend on the contribution of MSCs to building a supporting stroma, but the effects of MSCs appear to go beyond the mere supply of connective tissues. MSCs show targeted “homing” toward growing tumors, which is then followed by exerting direct and indirect effects on cancer cells. Several research groups have developed novel strategies that make use of the tumor tropism of MSCs by engineering them to express a transgene that enables an attack on cancer growth. This review aims to familiarize the reader with the current knowledge about MSC biology, the existing evidence for MSC contribution to tumor growth with its underlying mechanisms, and the strategies that have been developed using MSCs to deploy an anticancer therapy.

Sera of Overweight Patients Alter Adipogenesis and Osteogenesis of Bone Marrow Mesenchymal Stromal Cells, a Phenomenon that also Persists in Weight Loss Individuals

Background: Overweight and obesity represents a complex interaction of genetics, diet, metabolism, and physical activity. Abnormal or excessive body fat accumulation increases the risk of pathologies, such as heart disease, diabetes, and high blood pressure. Methods and results: In a previous paper, we investigated the influence of overweight individuals’ sera on in vitro biology of mesenchymal stromal cells, which contain a subpopulation of multipotent stem cells. This report extended the study by evaluating effects of sera collected from weight loss patients on stromal cultures. Results showed that an increase in fat mass induces physiological changes that negatively impact on stromal stem cell adipogenesis and osteogenesis with a bias toward adipocyte differentiation. This phenomenon occurred with sera from overweight patients and persisted also with sera of individuals that underwent loss of weight. Significant changes in obesity related cytokines were detected in sera of overweight and weight loss compared to healthy weight individuals. These changes may explain some of the biological effects detected on stromal stem cell functions.

Localization and functions of mesenchymal stromal cells in vivo

Studying mesenchymal stromal cells (MSC) is a very topical problem. Numerous experiments in vitro promoted understanding of MSC biology to a great extent. However, many aspects of their behavior in vivo still remain unclear. This review deals with MSC localization and functioning in an organism. MSC are present in various tissues, changing their numbers and traits during ontogenesis. Pericytes, or adventitial cells, can be considered as possible equivalents of MSC in vivo. Self-maintenance, proliferation, and differentiation of MSC are controlled by their tissue microenvironment that includes surrounding cells, soluble molecules, and extracellular matrix. At early stages of ontogenesis, MSC, probably, migrate throughout an organism. The migration occur also through a mature organism when tissues happen to be damaged. MSC move pointedly to the damaged parts and render a reparative effect which is due, first of all, to paracrine production of bioactive molecules. Immunomodulatory properties of MSC also play their role in tissues regeneration. An important function of MSC consists in creation of hematopoietic microenvironment. They secrete humoral regulators of hemopoiesis such as cytokines and chemoattractants. In addition, they interact with hemopoietic cells via surface molecules. Possibly, MSC sustain the stable functioning of other tissues as well. Their unique features make them quite attractive for clinical use, although successful introduction of MSC into medical practice requires their further studying.

Homing and migration of mesenchymal stromal cells: How to improve the efficacy of cell therapy?

Mesenchymal stromal cells (MSCs) are currently being investigated for use in a wide variety of clinical applications. For most of these applications, systemic delivery of the cells is preferred. However, this requires the homing and migration of MSCs to a target tissue. Although MSC homing has been described, this process does not appear to be highly efficacious because only a few cells reach the target tissue and remain there after systemic administration. This has been ascribed to low expression levels of homing molecules, the loss of expression of such molecules during expansion, and the heterogeneity of MSCs in cultures and MSC culture protocols. To overcome these limitations, different methods to improve the homing capacity of MSCs have been examined. Here, we review the current understanding of MSC homing, with a particular focus on homing to bone marrow. In addition, we summarize the strategies that have been developed to improve this process. A better understanding of MSC biology, MSC migration and homing mechanisms will allow us to prepare MSCs with optimal homing capacities. The efficacy of therapeutic applications is dependent on efficient delivery of the cells and can, therefore, only benefit from better insights into the homing mechanisms.

Novel Evidence That Murine and Human Mesenchymal Stromal Cells Express Functional Gonadotropic Hormone Receptors, Demonstrating the Involvement of the Pituitary gonadotropin–bone Marrow Axis in Hematopoiesis

Background: Mesenchymal stromal cells (MSCs) play an important role in bone marrow (BM) by providing a supportive microenvironment for hematopoietic stem/progenitor cells (HSPCs). MSCs are also employed in organ regeneration as a rich source of several paracrine signals that inhibit apoptosis and promote angiogenesis in damaged tissues. As reported in the literature, several mediators, including a growth factor (HGF), a chemokine (SDF-1), bioactive lipids (S1P, C1P), and extracellular nucleotides (ATP, UTP), affect MSC biology and migration. In parallel, evidence has accumulated that the most primitive mesodermal precursors of MSCs (small BM-residing and peripheral blood (PB)-circulating Sca-1+Lin–CD45– cells in mice and CD133+Lin–CD45– cells in humans) express certain embryonic stem cell markers, such as the transcription factor Oct-4 and the SSEA-1/4 antigens (Stem Cells Dev. 2014;23:689-701), and also express several genes characteristic of migrating primordial germ cells (Leukemia 2010; 24:1450–1461).Hypothesis: Pursuing observations that most primitive human and murine precursors of MSCs express several germline markers, we became interested in whether murine and human MSCs also express gonadotropic hormone receptors, such as receptors for follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL), and whether these receptors are functional.Materials and Methods: Murine and human MSCs were expanded from a population of adherent murine BM or human umbilical cord blood cells, and cells with low passage numbers were employed for analysis. The expression of gonadotropic receptors (FSH-R, LH-R, and PRL-R) was evaluated by RT-PCR, and the functionality of these receptors was tested in assays for proliferation, chemotaxis, adhesion, and phosphorylation of MAPKp42/44 and AKT. In addition, we also evaluated the expression of gonadotropin receptors by purified murine SKL cells and human CD34+ cells.Results. We report here for the first time that both human and murine MSCs and HSPCs express functional gonadotropin receptors. We found that FSH strongly enhanced proliferation of MSCs in vitro as well as expanded the number of these cells in murine BM after prolonged administration in vivo. We found that all these hormones stimulated chemotaxis and adhesion of murine and human MSCs. These functional responses were correlated with phosphorylation of MAPKp42/44 and AKT. At the same time, we observed that pituitary gonadotropin receptors are expressed by murine and human HSPCs and that these hormones stimulate proliferation and expansion of these cells in vivo in BM as well as in clonogeneic assays in vitro if added along with suboptimal doses of colony-stimulating growth factors. Of note, we did not observe significant differences in the effects of FSH, LH, and PRL between male and female cells.Conclusions. We provide for the first time evidence for the existence of a functional pituitary gonadotropin–hematopoiesis signaling axis, which has important implications for hematopoiesis in young individuals, and we will present gene-array data on changes in gene expression in MSCs after stimulation with gonadotropins. Moreover, since the levels of FSH and LH increase in response to a decrease in gonadal function with advanced age, elevated levels of FSH and LH may affect hematopoiesis and may be factors contributing to the development of leukemia. The stimulatory effect of pituitary gonadotropins on MSCs and HSPCs could also be exploited in the clinic in selected cases as a means to enhance hematopoiesis. DisclosuresNo relevant conflicts of interest to declare.