Survival Of Mesenchymal Stromal Cells Research Articles

Adiponectin restores the obesity-induced impaired immunomodulatory function of mesenchymal stromal cells via glycolytic reprogramming

Obesity has been known to negatively modulate the life-span and immunosuppressive potential of mesenchymal stromal cells (MSC). However, it remains unclear what drives the compromised potency of obese MSC. In this study, we examined the involvement of adiponectin, an adipose tissue-derived hormone, in obesity-induced impaired therapeutic function of MSC. Diet-induced obesity leads to a decrease in serum adiponectin, accompanied by impairment of survival and immunomodulatory effects of adipose-derived MSC (ADSC). Interestingly, priming with globular adiponectin (gAcrp) improved the immunomodulatory potential of obese ADSC. Similar effects were also observed in lean ADSC. In addition, gAcrp potentiated the therapeutic effectiveness of ADSC in a mouse model of DSS-induced colitis. Mechanistically, while obesity inhibited the glycolytic capacity of MSC, gAcrp treatment induced a metabolic shift toward glycolysis through activation of adiponectin receptor type 1/p38 MAPK/hypoxia inducible factor-1α axis. These findings suggest that activation of adiponectin signaling is a promising strategy for enhancing the therapeutic efficacy of MSC against immune-mediated disorders.

The Nephroprotective Effects of the Allogeneic Transplantation with Mesenchymal Stromal Cells Were Potentiated by ω3 Stimulating Up-Regulation of the PPAR-γ.

Mesenchymal stromal cells (MSCs) obtained from bone marrow are a promising tool for regenerative medicine, including kidney diseases. A step forward in MSCs studies is cellular conditioning through specific minerals and vitamins. The Omega-3 fatty acids (ω3) are essential in regulating MSCs self-renewal, cell cycle, and survival. The ω3 could act as a ligand for peroxisome proliferator-activated receptor gamma (PPAR-γ). This study aimed to demonstrate that ω3 supplementation in rats could lead to the up-regulation of PPAR-γ in the MSCs. The next step was to compare the effects of these MSCs through allogeneic transplantation in rats subjected to unilateral ureteral obstruction (UUO). Independent of ω3 supplementation in the diet of the rats, the MSCs in vitro conserved differentiation capability and phenotypic characteristics. Nevertheless, MSCs obtained from the rats supplemented with ω3 stimulated an increase in the expression of PPAR-γ. After allogeneic transplantation in rats subjected to UUO, the ω3 supplementation in the rats enhanced some nephroprotective effects of the MSCs through a higher expression of antioxidant enzyme (SOD-1), anti-inflammatory marker (IL-10), and lower expression of the inflammatory marker (IL-6), and proteinuria.

Heparin-collagen I bilayers stimulate FAK/ERK½ signaling via α2β1 integrin to support the growth and anti-inflammatory potency of mesenchymal stromal cells.

Understanding mesenchymal stromal cells (MSCs) growth mechanisms in response to surface chemistries is essential to optimize culture methods for high-quality and robust cell yields in cell manufacturing applications. Heparin (HEP) and collagen 1 (COL) substrates have been reported to enhance cell adhesion, growth, viability, and secretory potential in MSCs. However, the biomolecular mechanisms underlying the benefits of combined HEP/COL substrates are unknown. This work used HEP/COL bilayered surfaces to investigate the role of integrin-HEP interactions in the advantages of MSC culture. The layer-by-layer approach (LbL) was used to create HEP/COL bilayers, which were made up of stacks of 8 and 9 layers that combined HEP and COL in an alternate arrangement. Surface spectroscopic investigations and laser scanning microscopy evaluations verified the biochemical fingerprint of each component and a total stacked bilayer thickness of roughly 150 nm. Cell growth and apoptosis in response to IC50 and IC75 levels of BTT-3033 and Cilengitide, α2β1 and αvβ3 integrin inhibitors respectively, were evaluated on HEP/COL coated surfaces using two bone marrow-derived MSC donors. While integrin activity did not affect cell growth rates, it significantly affected cell adhesion and apoptosis on HEP/COL surfaces. HEP-ending HEP/COL surfaces significantly increased FAK-ERK½ phosphorylation and endogenous cell COL deposition compared to COL, COL-ending HEP/COL and uncoated surfaces. BTT-3033 but not Cilengitide treatment markedly affected FAK-ERK½ activity levels on HEP-ending HEP/COL surfaces supporting a major role for α2β1 activity. BTT-3033 treatment on HEP-ending bilayers reduced MSC-mediated macrophage inhibitory activity and altered the cytokine profile of co-cultures. Overall, this study supports a novel role for HEP in regulating the survival and potency of MSCs via enhancing the α2β1-FAK-ERK½ signaling mechanism.

844 Improvement of in vivo survival of mesenchymal stromal cells in immunodeficient mice

844 Improvement of in vivo survival of mesenchymal stromal cells in immunodeficient mice

Functional enhancement strategies to potentiate the therapeutic properties of mesenchymal stromal cells for respiratory diseases.

Respiratory diseases remain a major health concern worldwide because they subject patients to considerable financial and psychosocial burdens and result in a high rate of morbidity and mortality. Although significant progress has been made in understanding the underlying pathologic mechanisms of severe respiratory diseases, most therapies are supportive, aiming to mitigate symptoms and slow down their progressive course but cannot improve lung function or reverse tissue remodeling. Mesenchymal stromal cells (MSCs) are at the forefront of the regenerative medicine field due to their unique biomedical potential in promoting immunomodulation, anti-inflammatory, anti-apoptotic and antimicrobial activities, and tissue repair in various experimental models. However, despite several years of preclinical research on MSCs, therapeutic outcomes have fallen far short in early-stage clinical trials for respiratory diseases. This limited efficacy has been associated with several factors, such as reduced MSC homing, survival, and infusion in the late course of lung disease. Accordingly, genetic engineering and preconditioning methods have emerged as functional enhancement strategies to potentiate the therapeutic actions of MSCs and thus achieve better clinical outcomes. This narrative review describes various strategies that have been investigated in the experimental setting to functionally potentiate the therapeutic properties of MSCs for respiratory diseases. These include changes in culture conditions, exposure of MSCs to inflammatory environments, pharmacological agents or other substances, and genetic manipulation for enhanced and sustained expression of genes of interest. Future directions and challenges in efficiently translating MSC research into clinical practice are discussed.

Glucose Metabolism: Optimizing Regenerative Functionalities of Mesenchymal Stromal Cells Postimplantation.

Mesenchymal stromal cells (MSCs) are considered promising candidates for regenerative medicine applications. Their clinical performance postimplantation, however, has been disappointing. This lack of therapeutic efficacy is most likely due to suboptimal formulations of MSC-containing material constructs. Tissue engineers, therefore, have developed strategies addressing/incorporating optimized cell, microenvironmental, biochemical, and biophysical cues/stimuli to enhance MSC-containing construct performance. Such approaches have had limited success because they overlooked that maintenance of MSC viability after implantation for a sufficient time is necessary for MSCs to develop their regenerative functionalities fully. Following a brief overview of glucose metabolism and regulation in MSCs, the present literature review includes recent pertinent findings that challenge old paradigms and notions. We hereby report that glucose is the primary energy substrate for MSCs, provides precursors for biomass generation, and regulates MSC functions, including proliferation and immunosuppressive properties. More importantly, glucose metabolism is central in controlling in vitro MSC expansion, in vivo MSC viability, and MSC-mediated angiogenesis postimplantation when addressing MSC-based therapies. Meanwhile, in silico models are highlighted for predicting the glucose needs of MSCs in specific regenerative medicine settings, which will eventually enable tissue engineers to design viable and potent tissue constructs. This new knowledge should be incorporated into developing novel effective MSC-based therapies. Impact statement The clinical use of mesenchymal stromal cells (MSCs) has been unsatisfactory due to the inability of MSCs to survive and be functional after implantation for sufficient periods to mediate directly or indirectly a successful regenerative tissue response. The present review summarizes the endeavors in the past, but, most importantly, reports the latest findings that elucidate underlying mechanisms and identify glucose metabolism as the crucial parameter in MSC survival and the subsequent functions pertinent to new tissue formation of importance in tissue regeneration applications. These latest findings justify further basic research and the impetus for developing new strategies to improve the modalities and efficacy of MSC-based therapies.

Engineered Cell‐Secreted Extracellular Matrix Modulates Cell Spheroid Mechanosensing and Amplifies Their Response to Inductive Cues for the Formation of Mineralized Tissues (Adv. Healthcare Mater. 10/2022)

Mesenchymal Stromal Cells In article number 2102337 by J. Kent Leach and co-workers, an engineered cell-secreted extracellular matrix (ECM) is incorporated into mesenchymal stromal cell (MSC) spheroids to promote cell–cell and cell–matrix interactions and enhance MSC survival and differentiation. Activation of YAP through integrin binding to the incorporated ECM promotes MSC proliferation and osteogenic differentiation, highlighting the therapeutic potential of ECM-loaded spheroids as building blocks for bone repair.

Protease Activated Receptors: A Pathway to Boosting Mesenchymal Stromal Cell Therapeutic Efficacy in Acute Respiratory Distress Syndrome?

Acute Respiratory Distress Syndrome is the most common cause of respiratory failure among critically ill patients, and its importance has been heightened during the COVID-19 pandemic. Even with the best supportive care, the mortality rate in the most severe cases is 40–50%, and the only pharmacological agent shown to be of possible benefit has been steroids. Mesenchymal stromal cells (MSCs) have been tested in several pre-clinical models of lung injury and been found to have significant therapeutic benefit related to: (a) potent immunomodulation; (b) secretion of epithelial and endothelial growth factors; and (c) augmentation of host defense to infection. Initial translational efforts have shown signs of promise, but the results have not yielded the anticipated outcomes. One potential reason is the relatively low survival of MSCs in inflammatory conditions as shown in several studies. Therefore, strategies to boost the survival of MSCs are needed to enhance their therapeutic effect. Protease-activated receptors (PARs) may represent one such possibility as they are G-protein coupled receptors expressed by MSCs and control several facets of cell behavior. This review summarizes some of the existing literature about PARs and MSCs and presents possible future areas of investigation in order to develop potential, PAR-modified MSCs with enhanced therapeutic efficiency.

Eltrombopag in paediatric immune thrombocytopenia: Iron metabolism modulation in mesenchymal stromal cells.

SummaryImmune thrombocytopenia (ITP) is an autoimmune disease caused by platelet destruction mediated by auto‐antibody production. It is characterized by a compromised immune system and alteration of the inflammatory response. Mesenchymal stromal cells (MSCs) play an important role in modulating immune and inflammatory processes, exerting immune‐suppressing and anti‐inflammatory properties. In ITP‐MSCs the activity and survival are strongly impaired. Eltrombopag (ELT) is a thrombopoietin receptor agonist approved in chronic ITP for stimulating platelet production. It has immunomodulating properties by stimulating T and B regulatory cell activity and by promoting a macrophage switch from the pro‐inflammatory to the anti‐inflammatory phenotype. ELT also exhibits iron‐chelating properties. Iron is a crucial element involved in several physiologic processes, but its intracellular accumulation determines cell damages. Therefore, for the first time we analysed the effect of ELT on ITP‐MSCs demonstrating its ability to restore survival and activity of MSCs directly and to promote their survival and proliferation indirectly, by iron metabolism modulation.

Long noncoding RNA LUCAT1 enhances the survival and therapeutic effects of mesenchymal stromal cells post-myocardial infarction

Mesenchymal stromal cell (MSC) transplantation has been a promising therapeutic strategy for repairing heart tissues post-myocardial infarction (MI). Nevertheless, its therapeutic efficacy remains low, which is mainly ascribed to the low viability of transplanted MSCs. Recently, long noncoding RNAs (lncRNAs) have been reported to participate in diverse physiological and pathological processes, but little is known about their role in MSC survival. Using unbiased transcriptome profiling of hypoxia-preconditioned MSCs (HP-MSCs) and normoxic MSCs (N-MSCs), we identified a lncRNA named lung cancer-associated transcript 1 (LUCAT1) under hypoxia. LUCAT1 knockdown reduced the survival of engrafted MSCs and decreased the MSC-based therapeutic potency, as shown by impaired cardiac function, reduced cardiomyocyte survival, and increased fibrosis post-MI. Conversely, LUCAT1 overexpression had the opposite results. Mechanistically, LUCAT1 bound with and recruited jumonji domain-containing 6 (JMJD6) to the promoter of forkhead box Q1 (FOXQ1), which demethylated FOXQ1 at H4R3me2(s) and H3R2me2(a), thus downregulating Bax expression and upregulating Bcl-2 expression to attenuate MSC apoptosis. Therefore, our findings revealed the protective effects of LUCAT1 on MSC apoptosis and demonstrated that the LUCAT1-mediated JMJD6-FOXQ1 pathway might represent a novel target to potentiate the therapeutic effect of MSC-based therapy for ischemic cardiovascular diseases.

Craniofacial Bone Tissue Engineering: Current Approaches and Potential Therapy.

Craniofacial bone defects can result from various disorders, including congenital malformations, tumor resection, infection, severe trauma, and accidents. Successfully regenerating cranial defects is an integral step to restore craniofacial function. However, challenges managing and controlling new bone tissue formation remain. Current advances in tissue engineering and regenerative medicine use innovative techniques to address these challenges. The use of biomaterials, stromal cells, and growth factors have demonstrated promising outcomes in vitro and in vivo. Natural and synthetic bone grafts combined with Mesenchymal Stromal Cells (MSCs) and growth factors have shown encouraging results in regenerating critical-size cranial defects. One of prevalent growth factors is Bone Morphogenetic Protein-2 (BMP-2). BMP-2 is defined as a gold standard growth factor that enhances new bone formation in vitro and in vivo. Recently, emerging evidence suggested that Megakaryocytes (MKs), induced by Thrombopoietin (TPO), show an increase in osteoblast proliferation in vitro and bone mass in vivo. Furthermore, a co-culture study shows mature MKs enhance MSC survival rate while maintaining their phenotype. Therefore, MKs can provide an insight as a potential therapy offering a safe and effective approach to regenerating critical-size cranial defects.

Mesenchymal Stromal Cells Regulate Sialylations of N-Glycans, Affecting Cell Migration and Survival.

N-Glycosylations are an important post-translational modification of proteins that can significantly impact cell function. Terminal sialic acid in hybrid or complex N-glycans has been shown to be relevant in various types of cancer, but its role in non-malignant cells remains poorly understood. We have previously shown that the motility of human bone marrow derived mesenchymal stromal cells (MSCs) can be modified by altering N-glycoforms. The goal of this study was to determine the role of sialylated N-glycans in MSCs. Here, we show that IFN-gamma or exposure to culture media low in fetal bovine serum (FBS) increases sialylated N-glycans, while PDGF-BB reduces them. These stimuli alter mRNA levels of sialyltransferases such as ST3Gal1, ST6Gal1, or ST3Gal4, suggesting that sialylation of N-glycans is regulated by transcriptional control of sialyltransferases. We next show that 2,4,7,8,9-pentaacetyl-3Fax-Neu5Ac-CO2Me (3F-Neu5Ac) effectively inhibits sialylations in MSCs. Supplementation with 3F-Neu5Ac increases adhesion and migration of MSCs, as assessed by both videomicroscopy and wound/scratch assays. Interestingly, pre-treatment with 3F-Neu5Ac also increases the survival of MSCs in an in vitro ischemia model. We also show that pre-treatment or continuous treatment with 3F-Neu5Ac inhibits both osteogenic and adipogenic differentiation of MSCs. Finally, secretion of key trophic factors by MSCs is variably affected upon exposure to 3F-Neu5Ac. Altogether, our experiments suggest that sialylation of N-glycans is tightly regulated in response to environmental cues and that glycoengineering MSCs to reduce sialylated N-glycans could be beneficial to increase both cell migration and survival, which may positively impact the therapeutic potential of the cells.

Short lifespan of syngeneic transplanted MSC is a consequence of in vivo apoptosis and immune cell recruitment in mice

Mesenchymal stromal cells (MSC) are attractive tools for cell-based therapy, yet the mechanisms underlying their migration and survival post-transplantation are unclear. Accumulating evidence indicates that MSC apoptosis modulates both innate and adaptive immune responses which impact on MSC therapeutic effects. Using a dual tracking system, namely the Luciferase expression and VivoTrack680 labelling, and in vivo optical imaging, we investigated the survival and migration of MSC transplanted by various routes (intravenous, subcutaneous, intrapancreatic and intrasplenic) in order to identify the best delivery approach that provides an accumulation of therapeutic cells to the injured pancreas in the non-obese diabetic (NOD) mouse. The results showed that transplanted MSC had limited migration capacity, irrespective of the administration route, and were short-lived with almost total disappearance at 7 days after transplantation. Within one day after transplantation, cells activated hypoxia signalling pathways, followed by Caspase 3-mediated apoptosis. These were subsequently followed by local recruitment of immune cells at the transplantation site, and the engulfment of apoptotic MSC by macrophages. Our results argue for a “hit and die” mechanism of transplanted MSC. Further investigations will elucidate the molecular crosstalk between the inoculated and the host-immune cells.

Splenic macrophage phagocytosis of intravenously infused mesenchymal stromal cells attenuates tumor localization

Mesenchymal stromal cells (MSCs) possess remarkable tumor tropism, making them ideal vehicles to deliver tumor-targeted therapeutic agents; however, their value in clinical medicine has yet to be realized. A barrier to clinical utilization is that only a small fraction of infused MSCs ultimately localize to the tumor. In an effort to overcome this obstacle, we sought to enhance MSC trafficking by focusing on the factors that govern MSC arrival within the tumor microenvironment. Our findings show that MSC chemoattraction is only present in select tumors, including osteosarcoma, and that the chemotactic potency among similar tumors varies substantially. Using an osteosarcoma xenograft model, we show that human MSCs traffic to the tumor within several hours of infusion. After arrival, MSCs are observed to localize in clusters near blood vessels and MSC-associated bioluminescence signal intensity is increased, suggesting that the seeded cells expand after engraftment. However, our studies reveal that a significant portion of MSCs are eliminated en route by splenic macrophage phagocytosis, effectively limiting the number of cells available for tumor engraftment. To increase MSC survival, we transiently depleted macrophages with liposomal clodronate, which resulted in increased tumor localization without substantial reduction in tumor-associated macrophages. Our data suggest that transient macrophage depletion will significantly increase the number of MSCs in the spleen and thus improve MSC localization within a tumor, theoretically increasing the effective dose of an anti-cancer agent. This strategy may subsequently improve the clinical efficacy of MSCs as vehicles for the tumor-directed delivery of therapeutic agents.

Dimethyloxalylglycine, a small molecule, synergistically increases the homing and angiogenic properties of human mesenchymal stromal cells when cultured as 3D spheroids.

Strategies aiming at increasing the survival and paracrine activity of human mesenchymal stromal cells (MSCs) are of utmost importance to achieve the full therapeutic potential of these cells. Herein, we propose both physical and biochemical strategies to enhance the survival, homing, angiogenic, and immunomodulatory properties of MSCs in vitro. To that purpose, we compared the effect of exposing either 2D monolayer or 3D spheroids of MSCs to (i) hypoxia (2% O2 ) or to (ii) a hypoxic-mimetic small molecule, dimethyloxalylglycine (DMOG), with cells cultured at 21% O2 . 3D-cultured MSC spheroids evidenced higher survival upon exposure to oxidative stress and expressed higher levels of factors involved in tissue repair processes, namely tumor necrosis factor-stimulated gene-6, matrix metalloproteinase-2, and vascular endothelial growth factor. MSCs cultured as 3D spheroids and further exposed to hypoxia or hypoxic-mimetic conditions provided by DMOG synergistically favored the expression of the cell surface marker C-X-C chemokine receptor type-4, involved in homing processes to injured tissues, and adhesion to extracellular matrix components as fibronectin. These results highlight the role of ex vivo preconditioning approaches, presenting a novel strategy that combine biochemical stimuli with 3D spheroid organization of MSCs to maximize their tissue regeneration potential.

Enhanced cell survival and therapeutic benefits of IL-10-expressing multipotent mesenchymal stromal cells for muscular dystrophy

BackgroundMultipotent mesenchymal stromal cells (MSCs) are potentially therapeutic for muscle disease because they can accumulate at the sites of injury and act as immunosuppressants. MSCs are attractive candidates for cell-based strategies that target diseases with chronic inflammation, such as Duchenne muscular disease (DMD). We focused on the anti-inflammatory properties of IL-10 and hypothesized that IL-10 could increase the typically low survival of MSCs by exerting a paracrine effect after transplantation.MethodsWe developed a continuous IL-10 expression system of MSCs using an adeno-associated virus (AAV) vector. To investigate the potential benefits of IL-10 expressing AAV vector-transduced MSCs (IL-10-MSCs), we examined the cell survival rates in the skeletal muscles after intramuscular injection into mice and dogs. Systemic treatment with IL-10-MSCs derived from dental pulp (DPSCs) was comprehensively analyzed using the canine X-linked muscular dystrophy model in Japan (CXMDJ), which has a severe phenotype similar to that of DMD patients.ResultsIn vivo bioluminescence imaging analysis revealed higher retention of IL-10-MSCs injected into the hindlimb muscle of mice. In the muscles of dogs, myofiber-like tissue was formed after the stable engraftment of IL-10-MSCs. Repeated systemic administration of IL-10-DPSCs into the CXMDJ model resulted in long-term engraftment of cells and slightly increased the serum levels of IL-10. IL-10-hDPSCs showed significantly reduced expression of pro-inflammatory MCP-1 and upregulation of stromal-derived factor-1 (SDF-1). MRI and histopathology of the hDPSC-treated CXMDJ indicated the regulation of inflammation in the muscles, but not myogenic differentiation from treated cells. hDPSC-treated CXMDJ showed improved running capability and recovery in tetanic force with concomitant increase in physical activity. Serum creatine kinase levels, which increased immediately after exercise, were suppressed in IL-10-hDPSC-treated CXMDJ.ConclusionsIn case of local injection, IL-10-MSCs could maintain the long-term engraftment status and facilitate associated tissue repair. In case of repeated systemic administration, IL-10-MSCs facilitated the long-term retention of the cells in the skeletal muscle and also protected muscles from physical damage-induced injury, which improved muscle dysfunction in DMD. We can conclude that the local and systemic administration of IL-10-producing MSCs offers potential benefits for DMD therapy through the beneficial paracrine effects of IL-10 involving SDF-1.

Premature Senescence of T-cells Favors Bone Loss During Osteolytic Diseases. A New Concern in the Osteoimmunology Arena.

Cellular senescence is a biological process triggered in response to time-accumulated DNA damage, which prioritizes cell survival over cell function. Particularly, senescent T lymphocytes can be generated prematurely during chronic inflammatory diseases regardless of chronological aging. These senescent T lymphocytes are characterized by the loss of CD28 expression, a co-stimulatory receptor that mediates antigen presentation and effective T-cell activation. An increased number of premature senescent CD4+CD28- T lymphocytes has been frequently observed in osteolytic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, osteopenia, osteoporosis, and osteomyelitis. Indeed, CD4+CD28- T lymphocytes produce higher levels of osteoclastogenic molecular mediators directly related to pathologic bone loss, such as tumor necrosis factor (TNF)-α, interleukin (IL)-17A, and receptor-activator of nuclear factor κB ligand (RANKL), as compared with regular CD4+CD28+ T lymphocytes. In addition, premature senescent CD8+CD28- T lymphocytes have been negatively associated with bone healing and regeneration by inhibiting osteoblast differentiation and mesenchymal stromal cell survival. Therefore, accumulated evidence supports the role of senescent T lymphocytes in osteoimmunology. Moreover, premature senescence of T-cells seems to be associated with the functional imbalance between the osteolytic T-helper type-17 (Th17) and bone protective T regulatory (Treg) lymphocytes, as well as the phenotypic instability of Treg lymphocytes responsible for its trans-differentiation into RANKL-producing exFoxp3Th17 cells, a key cellular phenomenon directly related to bone loss. Herein, we present a framework for the understanding of the pathogenic characteristics of T lymphocytes with a premature senescent phenotype; and particularly, we revise and discuss their role in the osteoimmunology of osteolytic diseases.

Novel insights for improving the therapeutic safety and efficiency of mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) have attracted great interest in the field of regenerative medicine. They can home to damaged tissue, where they can exert pro-regenerative and anti-inflammatory properties. These therapeutic effects involve the secretion of growth factors, cytokines, and chemokines. Moreover, the functions of MSCs could be mediated by extracellular vesicles (EVs) that shuttle various signaling messengers. Although preclinical studies and clinical trials have demonstrated promising therapeutic results, the efficiency and the safety of MSCs need to be improved. After transplantation, MSCs face harsh environmental conditions, which likely dampen their therapeutic efficacy. A possible strategy aiming to improve the survival and therapeutic functions of MSCs needs to be developed. The preconditioning of MSCs ex vivo would strength their capacities by preparing them to survive and to better function in this hostile environment. In this review, we will discuss several preconditioning approaches that may improve the therapeutic capacity of MSCs. As stated above, EVs can recapitulate the beneficial effects of MSCs and may help avoid many risks associated with cell transplantation. As a result, this novel type of cell-free therapy may be safer and more efficient than the whole cell product. We will, therefore, also discuss current knowledge regarding the therapeutic properties of MSC-derived EVs.

Mesenchymal Stromal Cells' Therapy for Polyglutamine Disorders: Where Do We Stand and Where Should We Go?

Polyglutamine (polyQ) diseases are a group of inherited neurodegenerative disorders caused by the expansion of the cytosine-adenine-guanine (CAG) repeat. This mutation encodes extended glutamine (Q) tract in the disease protein, resulting in the alteration of its conformation/physiological role and in the formation of toxic fragments/aggregates of the protein. This group of heterogeneous disorders shares common molecular mechanisms, which opens the possibility to develop a pan therapeutic approach. Vast efforts have been made to develop strategies to alleviate disease symptoms. Nonetheless, there is still no therapy that can cure or effectively delay disease progression of any of these disorders. Mesenchymal stromal cells (MSC) are promising tools for the treatment of polyQ disorders, promoting protection, tissue regeneration, and/or modulation of the immune system in animal models. Accordingly, data collected from clinical trials have so far demonstrated that transplantation of MSC is safe and delays the progression of some polyQ disorders for some time. However, to achieve sustained phenotypic amelioration in clinics, several treatments may be necessary. Therefore, efforts to develop new strategies to improve MSC’s therapeutic outcomes have been emerging. In this review article, we discuss the current treatments and strategies used to reduce polyQ symptoms and major pre-clinical and clinical achievements obtained with MSC transplantation as well as remaining flaws that need to be overcome. The requirement to cross the blood-brain-barrier (BBB), together with a short rate of cell engraftment in the lesioned area and low survival of MSC in a pathophysiological context upon transplantation may contribute to the transient therapeutic effects. We also review methods like pre-conditioning or genetic engineering of MSC that can be used to increase MSC survival in vivo, cellular-free approaches—i.e., MSC-conditioned medium (CM) or MSC-derived extracellular vesicles (EVs) as a way of possibly replacing the use of MSC and methods required to standardize the potential of MSC/MSC-derived products. These are fundamental questions that need to be addressed to obtain maximum MSC performance in polyQ diseases and therefore increase clinical benefits.

Overexpression of alpha-1 antitrypsin in mesenchymal stromal cells improves their intrinsic biological properties and therapeutic effects in nonobese diabetic mice.

Islet/β cell dysfunction and death caused by autoimmune‐mediated injuries are major features of type 1 diabetes (T1D). Mesenchymal stromal cells (MSCs) have been used for the treatment of T1D in animal models and clinical trials. Based on the anti‐inflammatory effects of alpha‐1 antitrypsin (AAT), we generated human AAT engineered MSCs (hAAT‐MSCs) by infecting human bone marrow‐derived MSCs with the pHAGE CMV‐a1aT‐UBC‐GFP‐W lentiviral vector. We compared the colony forming, differentiation, and migration capacity of empty virus‐treated MSCs (hMSC) and hAAT‐MSCs and tested their protective effects in the prevention of onset of T1D in nonobese diabetic (NOD) mice. hAAT‐MSCs showed increased self‐renewal, better migration and multilineage differentiation abilities compared to hMSCs. In addition, polymerase chain reaction array for 84 MSC‐related genes showed that 23 genes were upregulated, and 3 genes were downregulated in hAAT‐MSCs compared to hMSCs. Upregulated genes include those critical for the stemness (ie, Wnt family member 3A [WNT3A], kinase insert domain receptor [KDR]), migration (intercellular adhesion molecule 1 [ICAM‐1], vascular cell adhesion protein 1 [VICAM‐1], matrix metalloproteinase‐2 [MMP2]), and survival (insulin‐like growth factor 1 [IGF‐1]) of MSCs. Pathway analysis showed that changed genes were related to growth factor activity, positive regulation of cell migration, and positive regulation of transcription. In vivo, a single intravenous infusion of hAAT‐MSCs significantly limited inflammatory infiltration into islets and delayed diabetes onset in the NOD mice compared with those receiving vehicle or hMSCs. Taken together, overexpression of hAAT in MSCs improved intrinsic biological properties of MSCs needed for cellular therapy for the treatment of T1D.