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Abstract Mesenchymal stromal cells (MSCs) from both humans and horses, which represent a clinically relevant translation animal model for human cutaneous wound healing, were recently found to possess antimicrobial properties against planktonic bacteria, and in the case of equine MSCs, also against biofilms. This, together with previous findings that human and equine MSCs promote angiogenesis and wound healing, makes these cells an attractive approach to treat infected cutaneous wounds in both species. The anti‐biofilm activities of equine MSC, via secretion of cysteine proteases, have only been demonstrated in vitro, thus lacking information about in vivo relevance. Moreover, the effects of the equine MSC secretome on resident skin cells have not yet been explored. The goals of this study were to (a) test the efficacy of the MSC secretome in a physiologically relevant ex vivo equine skin biofilm explant model and (b) explore the impact of the MSC secretome on the antimicrobial defense mechanisms of resident skin cells. Our salient findings were that secreted factors from equine MSCs significantly decreased viability of methicillin‐resistant Staphylococcus aureus bacteria in mature biofilms in this novel skin biofilm explant model. Moreover, we demonstrated that equine MSCs secrete CCL2 that increases the antimicrobial activity of equine keratinocytes by stimulating expression of antimicrobial peptides. Collectively, these data contribute to our understanding of the MSC secretome's antimicrobial properties, both directly by killing bacteria and indirectly by stimulating immune responses of surrounding resident skin cells, thus further supporting the value of MSC secretome‐based treatments for infected wounds.

Abstract The secretome of mesenchymal stromal cells (MSCs) derived from different tissue sources is considered an innovative therapeutic tool for regenerative medicine. Although adipose tissue‐and bone marrow‐derived MSCs (ADSCs and BMSCs, respectively) share many biological features, the different tissue origins can be mirrored by variations in their secretory profile, and in particular in the secreted extracellular vesicles (EVs). In this study, we carried out a detailed and comparative characterization of middle‐ and small‐sized EVs (mEVs and sEVs, respectively) released by either ADSCs or BMSCs. Their involvement in an endochondral ossification setting was investigated using ex vivo metatarsal culture models that allowed to explore both blood vessel sprouting and bone growth plate dynamics. Although EVs separated from both cell sources presented similar characteristics in terms of size, concentration, and marker expression, they exhibited different characteristics in terms of protein content and functional effects. ADSC‐EVs overexpressed pro‐angiogenic factors in comparison to the BMSC‐counterpart, and, consequently, they were able to induce a significant increase in endothelial cord outgrowth. On the other hand, BMSC‐EVs contained a higher amount of pro‐differentiation and chemotactic proteins, and they were able to prompt growth plate organization. The present study highlights the importance of selecting the appropriate cell source of EVs for targeted therapeutic applications.

Abstract Buerger's disease or thromboangiitis obliterans is a type of obstructive vascular diseases categorized as vasculitis and usually present in 95% of young smoker men. The main pathogenetic mechanism is interplay between immune system and inflammation. Earlier our phase II study has shown that Stempeucel is safe when injected at 2 million cells/kg body weight by virtue of its anti‐inflammatory, immunomodulatory, and angiogenetic properties. The present study was conducted to further assess the safety and efficacy of Stempeucel in critical limb ischemia due to Buerger's disease after obtaining approval from Indian FDA based on the data generated in the phase II study. This is an open label, multicenteric phase IV PMS study conducted across India with experienced vascular surgeons. Fifty patients of critical limb ischemia due to Buerger's disease with Rutherford III‐5 or III‐6 were included in the study and each individual received a dose of 2 million cells/kg body weight of Stempeucel in the calf muscles and around the ulcer. These patients were evaluated over 12 months from drug administration. The present study showed the continued long term efficacy over a period of 12 months follow up in these patients corroborating the result obtained in the previous phase II studies. There was significant improvement in rest pain, ankle systolic pressure, and ankle brachial pressure index with accelerated ulcer healing. In conclusion, the present study shows that the intramuscular administration of Stempeucel continues to be safe, tolerable, and effective alternative treatment in patients with Buerger's disease.

Abstract The paracrine signaling, immunogenic properties and possible applications of mesenchymal stromal cells (MSCs) for cartilage tissue engineering and regenerative medicine therapies have been investigated through numerous in vitro, animal model and clinical studies. The emerging knowledge largely supports the concept of MSCs as signaling and modulatory cells, exerting their influence through trophic and immune mediation rather than as a cell replacement therapy. The virtues of allogeneic cells as a ready‐to‐use product with well‐defined characteristics of cell surface marker expression, proliferative ability, and differentiation capacity are well established. With clinical applications in mind, a greater focus on allogeneic cell sources is evident, and this review summarizes the latest published and upcoming clinical trials focused on cartilage regeneration adopting allogeneic and autologous cell sources. Moreover, we review the current understanding of immune modulatory mechanisms and the role of trophic factors in articular chondrocyte‐MSC interactions that offer feasible targets for evaluating MSC activity in vivo within the intra‐articular environment. Furthermore, bringing labeling and tracking techniques to the clinical setting, while inherently challenging, will be extremely informative as clinicians and researchers seek to bolster the case for the safety and efficacy of allogeneic MSCs. We therefore review multiple promising approaches for cell tracking and labeling, including both chimerism studies and imaging‐based techniques, that have been widely explored in vitro and in animal models. Understanding the distribution and persistence of transplanted MSCs is necessary to fully realize their potential in cartilage regeneration techniques and tissue engineering applications.

Abstract Cell‐based therapy for the treatment of inflammatory disorders has focused on the application of mesenchymal stromal cells (MSCs) and multipotent adult progenitor cells (MAPCs). Despite the recent positive findings in industry‐sponsored clinical trials of MSCs and MAPCs for graft vs host disease (GvHD), cell therapy is efficacious in some but not all patients, highlighting the need to identify strategies to enhance cell‐based therapeutic efficacy. Here, we demonstrate the capacity for interferon (IFN)‐γ licensing to enhance human MAPC efficacy and retention following early administration in a humanized mouse model of acute GvHD (aGvHD). Activation of the nuclear receptor peroxisome proliferator‐activated receptor delta (PPARδ) negatively influenced the retention and efficacy of human MAPCs as well as IFN‐γ‐licensed MAPCs in the aGvHD model. PPARδ antagonism significantly enhanced the efficacy of human MAPCs when administered early in the humanized aGvHD model. COX‐2 expression in human MAPC was significantly decreased in IFN‐γ licensed MAPCs exposed to a PPARδ agonist. Importantly, MAPC exposure to the PPARδ antagonist in the presence of a COX‐2 inhibitor indomethacin before administration significantly reduced the efficacy of PPARδ antagonized MAPCs in the aGvHD humanized mouse model. This is the first study to demonstrate the importance of PPARδ in human MAPC efficacy in vivo and highlights the importance of understanding the disease microenvironment in which cell‐based therapies are to be administered. In particular, the presence of PPARδ ligands may negatively influence MAPC or MSC therapeutic efficacy.

Despite recent advances in neonatal intensive care medicine, neonatal disorders such as (bronchopulmonary dysplasia [BPD], intraventricular hemorrhage [IVH], and hypoxic ischemic encephalopathy [HIE]) remain major causes of death and morbidity in survivors, with few effective treatments being available. Recent preclinical studies have demonstrated the pleiotropic host injury-responsive paracrine protective effects of cell therapy especially with mesenchymal stromal cells (MSCs) against BPD, IVH, and HIE. These findings suggest that MSCs therapy might emerge as a novel therapeutic modality for these currently devastating neonatal disorders with complex multifactorial etiologies. Although early-phase clinical trials suggest their safety and feasibility, their clinical therapeutic benefits have not yet been proven. Therefore, based on currently available preclinical research and clinical trial data, we focus on critical issues that need to be addressed for future successful clinical trials and eventual clinical translation such as selecting the right patient and optimal cell type, route, dose, and timing of MSCs therapy for neonatal disorders such as BPD, HIE, and IVH., (© The Author(s) 2024. Published by Oxford University Press.)

Abstract One of the main causes of acute respiratory distress syndrome in coronavirus disease 2019 (COVID‐19) is cytokine storm, although the exact cause is still unknown. Umbilical cord mesenchymal stromal cells (UC‐MSCs) influence proinflammatory T‐helper 2 (Th2) cells to shift to an anti‐inflammatory agent. To investigate efficacy of UC‐MSC administration as adjuvant therapy in critically ill patients with COVID‐19, we conducted a double‐blind, multicentered, randomized controlled trial at four COVID‐19 referral hospitals in Jakarta, Indonesia. This study included 40 randomly allocated critically ill patients with COVID‐19; 20 patients received an intravenous infusion of 1 × 106/kg body weight UC‐MSCs in 100 ml saline (0.9%) solution (SS) and 20 patients received 100 ml 0.9% SS as the control group. All patients received standard therapy. The primary outcome was measured by survival rate and/or length of ventilator usage. The secondary outcome was measured by clinical and laboratory improvement, with serious adverse events. Our study showed the survival rate in the UC‐MSCs group was 2.5 times higher than that in the control group (P = .047), which is 10 patients and 4 patients in the UC‐MSCs and control groups, respectively. In patients with comorbidities, UC‐MSC administration increased the survival rate by 4.5 times compared with controls. The length of stay in the intensive care unit and ventilator usage were not statistically significant, and no adverse events were reported. The application of infusion UC‐MSCs significantly decreased interleukin 6 in the recovered patients (P = .023). Therefore, application of intravenous UC‐MSCs as adjuvant treatment for critically ill patients with COVID‐19 increases the survival rate by modulating the immune system toward an anti‐inflammatory state.

Abstract Human mesenchymal stromal cells (MSCs) are promising candidates for cell therapy due to their ease of isolation and expansion and their ability to secrete antiapoptotic, pro‐angiogenic, and immunomodulatory factors. Three‐dimensional (3D) aggregation “self‐activates” MSCs to augment their pro‐angiogenic and immunomodulatory potential, but the microenvironmental features and culture parameters that promote optimal MSC immunomodulatory function in 3D aggregates are poorly understood. Here, we generated MSC aggregates via three distinct methods and compared them with regard to their (a) aggregate structure and (b) immunomodulatory phenotype under resting conditions and in response to inflammatory stimulus. Methods associated with fast aggregation kinetics formed aggregates with higher cell packing density and reduced extracellular matrix (ECM) synthesis compared to those with slow aggregation kinetics. While all three methods of 3D aggregation enhanced MSC expression of immunomodulatory factors compared to two‐dimensional culture, different aggregation methods modulated cells' temporal expression of these factors. A Design of Experiments approach, in which aggregate size and aggregation kinetics were systematically covaried, identified a significant effect of both parameters on MSCs' ability to regulate immune cells. Compared to small aggregates formed with fast kinetics, large aggregates with slow assembly kinetics were more effective at T‐cell suppression and macrophage polarization toward anti‐inflammatory phenotypes. Thus, culture parameters including aggregation method, kinetics, and aggregate size influence both the structural properties of aggregates and their paracrine immunomodulatory function. These findings underscore the utility of engineering strategies to control properties of 3D MSC aggregates, which may identify new avenues for optimizing the immunomodulatory function of MSC‐based cell therapies.

Abstract Cell‐based therapies hold promise to substantially curb complications from extreme preterm birth, the main cause of death in children below the age of 5 years. Exciting preclinical studies in experimental neonatal lung injury have provided the impetus for the initiation of early phase clinical trials in extreme preterm infants at risk of developing bronchopulmonary dysplasia. Clinical translation of promising therapies, however, is slow and often fails. In the adult population, results of clinical trials so far have not matched the enticing preclinical data. The neonatal field has experienced many hard‐earned lessons with the implementation of oxygen therapy or postnatal steroids. Here we briefly summarize the preclinical data that have permitted the initiation of early phase clinical trials of cell‐based therapies in extreme preterm infants and describe the INCuBAToR concept (Innovative Neonatal Cellular Therapy for Bronchopulmonary Dysplasia: Accelerating Translation of Research), an evidence‐based approach to mitigate the risk of translating advanced therapies into this vulnerable patient population. The INCuBAToR addresses several of the shortcomings at the preclinical and the clinical stage that usually contribute to the failure of clinical translation through (a) systematic reviews of preclinical and clinical studies, (b) integrated knowledge transfer through engaging important stakeholders early on, (c) early economic evaluation to determine if a novel therapy is viable, and (d) retrospective and prospective studies to define and test ideal eligibility criteria to optimize clinical trial design. The INCuBAToR concept can be applied to any novel therapy in order to enhance the likelihood of success of clinical translation in a timely, transparent, rigorous, and evidence‐based fashion.

The mission of the California Institute of Regenerative Medicine (CIRM) is to accelerate treatments to patients with unmet medical needs. In September 2016, CIRM sponsored a workshop held at the University of California, Los Angeles, to discuss regenerative medicine approaches for treatment of lung diseases and to identify the challenges remaining for advancing such treatments to the clinic and market approval. Workshop participants discussed current preclinical and clinical approaches to regenerative medicine in the lung, as well as the biology of lung stem cells and the role of stem cells in the etiology of various lung diseases. The outcome of this effort was the recognition that whereas transient cell delivery approaches are leading the way in the clinic, recent advances in the understanding of lung stem cell biology, in vitro and in vivo disease modeling, gene editing and replacement methods, and cell engraftment approaches raise the prospect of developing cures for some lung diseases in the foreseeable future. In addition, advances in in vitro modeling using lung organoids and "lung on a chip" technology are setting the stage for high quality small molecule drug screening to develop treatments for lung diseases with complex biology. Stem Cells Translational Medicine 2017;6:1823-1828.

In this study, we engineered mesenchymal stem cells (MSCs) to over-express basic fibroblast growth factor (bFGF) and evaluated its effects on fracture healing. Adipose-derived mouse MSCs were transduced to express bFGF and green fluorescence protein (ADSCbFGF -GFP). Closed-femoral fractures were performed with osterix-mCherry reporter mice of both sexes. The mice received 3 × 105 ADSCs transfected with control vector or bFGF via intramuscular injection within or around the fracture sites. Mice were euthanized at days 7, 14, and 35 to monitor MSC engraftment, osteogenic differentiation, callus formation, and bone strength. Compared to ADSC culture alone, ADSCbFGF increased bFGF expression and higher levels of bFGF and vascular endothelial growth factor (VEGF) in the culture supernatant for up to 14 days. ADSCbFGF treatment increased GFP-labeled MSCs at the fracture gaps and these cells were incorporated into the newly formed callus. quantitative reverse transcription polymerase chain reaction (qRT-PCR) from the callus revealed a 2- to 12-fold increase in the expression of genes associated with nervous system regeneration, angiogenesis, and matrix formation. Compared to the control, ADSCbFGF treatment increased VEGF expression at the periosteal region of the callus, remodeling of collagen into mineralized callus and bone strength. In summary, MSCbFGF accelerated fracture healing by increasing the production of growth factors that stimulated angiogenesis and differentiation of MSCs to osteoblasts that formed new bone and accelerated fracture repair. This novel treatment may reduce the time required for fracture healing. Stem Cells Translational Medicine 2017;6:1880-1893.

The immunomodulatory activity of mesenchymal stem/stromal cells (MSCs) to suppress innate and adaptive immune responses offers a potent cell therapy for modulating inflammation and promoting tissue regeneration. However, the inflammatory cytokine milieu plays a critical role in stimulating MSC immunomodulatory activity. In particular, interferon-γ (IFN-γ)-induced expression of indoleamine 2,3-dioxygenase (IDO) is primarily responsible for MSC suppression of T-cell proliferation and activation. Although pretreatment with IFN-γ is commonly used to prime MSCs for immunomodulatory activity prior to transplantation, the transient effects of pretreatment may limit the potential of MSCs to potently modulate immune responses. Therefore, the objective of this study was to investigate whether microparticle-mediated presentation of bioactive IFN-γ within three-dimensional spheroidal MSC aggregates could precisely regulate and induce sustained immunomodulatory activity. Delivery of IFN-γ via heparin-microparticles within MSC aggregates induced sustained IDO expression during 1 week of culture, whereas IDO expression by IFN-γ-pretreated MSC spheroids rapidly decreased during 2 days. Furthermore, sustained IDO expression induced by IFN-γ-loaded microparticles resulted in an increased and sustained suppression of T-cell activation and proliferation in MSC cocultures with CD3/CD28-activated peripheral blood mononuclear cells. The increased suppression of T cells by MSC spheroids containing IFN-γ-loaded microparticles was dependent on induction of IDO and supported by affecting monocyte secretion from pro- to anti-inflammatory cytokines. Altogether, microparticle delivery of IFN-γ within MSC spheroids provides a potent means of enhancing and sustaining immunomodulatory activity to control MSC immunomodulation after transplantation and thereby improve the efficacy of MSC-based therapies aimed at treating inflammatory and immune diseases. Stem Cells Translational Medicine 2017;6:223-237.

Abstract Between 15% and 30% of HIV‐infected subjects fail to increase their CD4+ T‐cell counts despite continuous viral suppression (immunological nonresponders [INRs]). These subjects have a higher morbidity and mortality rate, but there are no effective treatments to reverse this situation so far. This study used data from an interrupted phase I/II clinical trial to evaluate safety and immune recovery after INRs were given four infusions, at baseline and at weeks 4, 8, and 20, with human allogeneic mesenchymal stromal cells from adipose tissue (Ad‐MSCs). Based on the study design, the first 5 out of 15 INRs recruited received unblinded Ad‐MSC infusions. They had a median CD4+ nadir count of 16/μL (range, 2‐180) and CD4+ count of 253 cells per microliter (171‐412) at baseline after 109 (54‐237) months on antiretroviral treatment and 69 (52‐91) months of continuous undetectable plasma HIV‐RNA. After a year of follow‐up, an independent committee recommended the suspension of the study because no increase of CD4+ T‐cell counts or CD4+/CD8+ ratios was observed. There were also no significant changes in the phenotype of different immunological lymphocyte subsets, percentages of natural killer cells, regulatory T cells, and dendritic cells, the inflammatory parameters analyzed, and cellular associated HIV‐DNA in peripheral blood mononuclear cells. Furthermore, three subjects suffered venous thrombosis events directly related to the Ad‐MSC infusions in the arms where the infusions were performed. Although the current study is based on a small sample of participants, the findings suggest that allogeneic Ad‐MSC infusions are not effective to improve immune recovery in INR patients or to reduce immune activation or inflammation. ClinicalTrials.gov identifier: NCT0229004. EudraCT number: 2014‐000307‐26.

Abstract 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.

Unlabelled: The induction of mesenchymal stem cells (MSCs) toward the osteoblastic lineage using osteogenic supplements prior to implantation is one approach under examination to enhance their bone-forming potential. MSCs rapidly lose their induced phenotype upon removal of the soluble stimuli; however, their bone-forming potential can be sustained when provided with continued instruction via extracellular matrix (ECM) cues. In comparison with dissociated cells, MSC spheroids exhibit improved survival and secretion of trophic factors while maintaining their osteogenic potential. We hypothesized that entrapment of MSC spheroids formed from osteogenically induced cells would exhibit better preservation of their bone-forming potential than would dissociated cells from monolayer culture. Spheroids exhibited comparable osteogenic potential and increased proangiogenic potential with or without osteogenic preconditioning versus monolayer-cultured MSCs. Spheroids were then entrapped in collagen hydrogels, and the osteogenic stimulus was removed. In comparison with entrapped dissociated MSCs, spheroids exhibited significantly increased markers of osteogenic differentiation. The capacity of MSC spheroids to retain their osteogenic phenotype upon withdrawal of inductive cues was mediated by α2β1 integrin binding to cell-secreted ECM. These results demonstrate the capacity of spheroidal culture to sustain the mineral-producing phenotype of MSCs, thus enhancing their contribution toward bone formation and repair.SignificanceDespite the promise of mesenchymal stem cells (MSCs) for cell-based therapies for tissue repair and regeneration, there is little evidence that transplanted MSCs directly contribute to new bone formation, suggesting that induced cells rapidly lose their osteogenic phenotype or undergo apoptosis. In comparison with dissociated cells, MSC spheroids exhibit increased trophic factor secretion and improved cell survival. The loss of phenotype represents a significant clinical challenge for cell therapies, yet there is no evidence for whether MSC spheroids retain their osteogenic phenotype upon entrapment in a clinically relevant biomaterial. These findings demonstrate that MSC spheroids retain their osteogenic phenotype better than do dissociated MSCs, and this is due to integrin engagement with the cell-secreted extracellular matrix. These data provide evidence for a novel approach for potentiating the use of MSCs in bone repair.

UnlabelledMesenchymal stem cell (MSC)-based therapies are under broad investigation for applications in tissue repair but suffer from poor cell persistence and engraftment upon transplantation. MSC spheroids exhibit improved survival, anti-inflammatory, and angiogenic potential in vitro, while also promoting vascularization when implanted in vivo. However, these benefits are lost once cells engage the tissue extracellular matrix and migrate from the aggregate. The efficacy of cell therapy is consistently improved when using engineered materials, motivating the need to investigate the role of biomaterials to instruct spheroid function. In order to assess the contribution of adhesivity on spheroid activity in engineered materials and promote the bone-forming potential of MSCs, we compared the function of MSC spheroids when entrapped in Arg-Gly-Asp (RGD)-modified alginate hydrogels to nonfouling unmodified alginate. Regardless of material, MSC spheroids exhibited reduced caspase activity and greater vascular endothelial growth factor (VEGF) secretion compared with equal numbers of dissociated cells. MSC spheroids in RGD-modified hydrogels demonstrated significantly greater cell survival than spheroids in unmodified alginate. After 5 days in culture, spheroids in RGD-modified gels had similar levels of apoptosis, but more than a twofold increase in VEGF secretion compared with spheroids in unmodified gels. All gels contained mineralized tissue 8 weeks after subcutaneous implantation, and cells entrapped in RGD-modified alginate exhibited greater mineralization versus cells in unmodified gels. Immunohistochemistry confirmed more diffuse osteocalcin staining in gels containing spheroids compared with dissociated controls. This study demonstrates the promise of cell-instructive biomaterials to direct survival and function of MSC spheroids for bone tissue engineering applications.SignificanceMesenchymal stem cell (MSC) spheroids exhibit improved therapeutic potential in vitro compared with dissociated MSCs, yet spheroids are directly injected into tissues, ceding control of cell function to the extracellular matrix and potentially limiting the duration of improvement. Cell delivery using adhesive biomaterials promotes cell retention and function. These studies explored the role of adhesion to the surrounding matrix on spheroid function. When entrapped in an adhesive biomaterial, MSC spheroids exhibited improved survival and proangiogenic growth factor secretion in vitro and bone formation in vivo compared with cells in nonadhesive hydrogels. These findings demonstrate the value of deploying MSC spheroids in instructive biomaterials to improve cell function.

Abstract Skin is the largest organ of the human body. Skin wound is one of the most common forms of wound. Mesenchymal stromal cells (MSCs) have been used to aid skin wound healing via their paracrine factors. Because the secretome of MSCs can be greatly enriched and amplified by treatment with IFN‐γ and TNF‐α (IT), we here tested whether supernatant derived from MSCs pretreated with IT, designated as S‐MSCs‐IT, possesses improved wound healing effect by using a murine model of cutaneous excision, S‐MSCs‐IT was found to be more potent in promoting angiogenesis, constricting collagen deposition and accelerating wound closure than control supernatant (S‐MSCs) during the healing of skin wound. VEGFC, but not VEGFA, was greatly upregulated by IT and was found to be a key factor in mediating the improved wound healing effect of S‐MSCs‐IT. Our results indicate that the beneficial paracrine effect of MSCs on wound healing can be enhanced by pretreatment with inflammatory cytokines. IT treatment may represent a new strategy for optimizing the therapeutic effect of MSCs on skin injuries.

Abstract Ongoing neuroinflammation may contribute to symptoms of autism spectrum disorder (ASD) in at least a portion of affected individuals. Mesenchymal stromal cells (MSCs) have demonstrated the capacity to modulate neuroinflammation, but safety and feasibility of MSC administration in children with ASD have not been well established. In this open‐label, phase I study, 12 children with ASD between 4 and 9 years of age were treated with intravenous (IV) infusions of human cord tissue mesenchymal stromal cells (hCT‐MSCs), a third‐party MSC product manufactured from unrelated donor umbilical cord tissue. Children received one, two, or three doses of 2 × 106 cells per kilogram at 2‐month intervals. Clinical and laboratory evaluations were performed in person at baseline and 6 months and remotely at 12 months after the final infusion. Aside from agitation during the IV placement and infusion in some participants, hCT‐MSCs were well tolerated. Five participants developed new class I anti‐human leukocyte antigen (HLA) antibodies, associated with a specific lot of hCT‐MSCs or with a partial HLA match between donor and recipient. These antibodies were clinically silent and not associated with any clinical manifestations to date. Six of 12 participants demonstrated improvement in at least two ASD‐specific measures. Manufacturing and administration of hCT‐MSCs appear to be safe and feasible in young children with ASD. Efficacy will be evaluated in a subsequent phase II randomized, placebo‐controlled clinical trial.

Abstract Severe cases of COVID‐19 infection, often leading to death, have been associated with variants of acute respiratory distress syndrome (ARDS). Cell therapy with mesenchymal stromal cells (MSCs) is a potential treatment for COVID‐19 ARDS based on preclinical and clinical studies supporting the concept that MSCs modulate the inflammatory and remodeling processes and restore alveolo‐capillary barriers. The authors performed a systematic literature review and random‐effects meta‐analysis to determine the potential value of MSC therapy for treating COVID‐19‐infected patients with ARDS. Publications in all languages from 1990 to March 31, 2020 were reviewed, yielding 2691 studies, of which nine were included. MSCs were intravenously or intratracheally administered in 117 participants, who were followed for 14 days to 5 years. All MSCs were allogeneic from bone marrow, umbilical cord, menstrual blood, adipose tissue, or unreported sources. Combined mortality showed a favorable trend but did not reach statistical significance. No related serious adverse events were reported and mild adverse events resolved spontaneously. A trend was found of improved radiographic findings, pulmonary function (lung compliance, tidal volumes, PaO2/FiO2 ratio, alveolo‐capillary injury), and inflammatory biomarker levels. No comparisons were made between MSCs of different sources.

Abstract Mesenchymal stromal cells (MSCs) have been a popular platform for cell‐based therapy in regenerative medicine due to their propensity to home to damaged tissue and act as a repository of regenerative molecules that can promote tissue repair and exert immunomodulatory effects. Accordingly, a great deal of research has gone into optimizing MSC homing and increasing their secretion of therapeutic molecules. A variety of methods have been used to these ends, but one emerging technique gaining significant interest is the use of ultrasound. Sound waves exert mechanical pressure on cells, activating mechano‐transduction pathways and altering gene expression. Ultrasound has been applied both to cultured MSCs to modulate self‐renewal and differentiation, and to tissues‐of‐interest to make them a more attractive target for MSC homing. Here, we review the various applications of ultrasound to MSC‐based therapies, including low‐intensity pulsed ultrasound, pulsed focused ultrasound, and extracorporeal shockwave therapy, as well as the use of adjunctive therapies such as microbubbles. At a molecular level, it seems that ultrasound transiently generates a local gradient of cytokines, growth factors, and adhesion molecules that facilitate MSC homing. However, the molecular mechanisms underlying these methods are far from fully elucidated and may differ depending on the ultrasound parameters. We thus put forth minimal criteria for ultrasound parameter reporting, in order to ensure reproducibility of studies in the field. A deeper understanding of these mechanisms will enhance our ability to optimize this promising therapy to assist MSC‐based approaches in regenerative medicine.

Abstract Here we report the case of successful immune tolerance induction in a living‐donor kidney transplant recipient remotely treated with autologous bone marrow‐derived mesenchymal stromal cells (MSC). This case report, which to the best of our knowledge is the first in the world in this setting, provides evidence that the modulation of the host immune system with MSC can enable the safe withdrawal of maintenance immunosuppressive drugs while preserving optimal long‐term kidney allograft function.

Abstract In experimental house dust mite (HDM)‐induced allergic asthma, therapeutic administration of a single dose of adipose tissue‐derived mesenchymal stromal cells (MSCs) ameliorates lung inflammation but is unable to reverse remodeling. We hypothesized that multiple doses of MSCs might exert better therapeutic effects by reducing lung inflammation and remodeling but might also result in immunosuppressive effects in experimental asthma. HDM was administered intranasally in C57BL/6 mice. After the last HDM challenge, mice received two or three doses of MSCs (105 cells per day) or saline intravenously. An additional cohort of mice received dexamethasone as a positive control for immunosuppression. Two and three doses of MSCs reduced lung inflammation, levels of interleukin (IL)‐4, IL‐13, and eotaxin; total leukocyte, CD4+ T‐cell, and eosinophil counts in bronchoalveolar lavage fluid; and total leukocyte counts in bone marrow, spleen, and mediastinal lymph nodes. Two and three doses of MSCs also reduced collagen fiber content and transforming growth factor‐β levels in lung tissue; however, the three‐dose regimen was more effective, and reduced these parameters to control levels, while also decreasing α‐actin content in lung tissue. Two and three doses of MSCs improved lung mechanics. Dexamethasone, two and three doses of MSCs similarly increased galectin levels, but only the three‐dose regimen increased CD39 levels in the thymus. Dexamethasone and the three‐dose, but not the two‐dose regimen, also increased levels of programmed death receptor‐1 and IL‐10, while reducing CD4+CD8low cell percentage in the thymus. In conclusion, multiple doses of MSCs reduced lung inflammation and remodeling while causing immunosuppression in HDM‐induced allergic asthma.

Abstract Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) have emerged as a promising form of regenerative therapy and immune modulation. Fundamental advances in our understanding of MSCs and EVs have allowed these fields to merge and create potential cell‐free therapy options that are cell‐based. EVs contain active cargo including proteins, microRNA, and mRNA species that can impact signaling responses in target cells to modify inflammatory and repair responses. Increasing numbers of preclinical studies in animals with various types of injury models have been published that demonstrate the potential impact of MSC‐EV therapy. Although the emergence of registered clinical protocols suggests translation to clinical application has already begun, several barriers to more widespread clinical adoption remain. In this review, we highlight the progress made in MSC‐derived small EV‐based therapy by summarizing aspects pertaining to the starting material for MSC expansion, EV production, and isolation methods, studies from preclinical models that have established a foundation of knowledge to support translation into the patient setting, and potential barriers to overcome on the path to clinical application.

Abstract Mesenchymal stromal cells (MSCs) are multipotent stem cells that participate in tissue repair and possess considerable immunomodulatory potential. MSCs have been shown to promote allograft survival, yet the mechanisms behind this phenomenon have not been fully defined. Here, we investigate the capacity of MSCs to suppress the allogeneic immune response by secreting the pleiotropic molecule hepatocyte growth factor (HGF). Using an in vivo mouse model of corneal transplantation, we report that MSCs promote graft survival in an HGF‐dependent manner. Moreover, our data indicate that topically administered recombinant HGF (a) suppresses antigen‐presenting cell maturation in draining lymphoid tissue, (b) limits T‐helper type‐1 cell generation, (c) decreases inflammatory cell infiltration into grafted tissue, and (d) is itself sufficient to promote transplant survival. These findings have potential translational implications for the development of HGF‐based therapeutics. Stem Cells Translational Medicine 2019;8:1030–1040

Abstract In preclinical studies, mesenchymal stromal cells (MSCs) exhibit robust potential for numerous applications. To capitalize on these benefits, cell manufacturing and delivery protocols have been scaled up to facilitate clinical trials without adequately addressing the impact of these processes on cell utility nor inevitable regulatory requirements for consistency. Growing evidence indicates that culture‐aged MSCs, expanded to the limits of replicative exhaustion to generate human doses, are not equivalent to early passage cells, and their use may underpin reportedly underwhelming or inconsistent clinical outcomes. Here, we sought to define the maximum expansion boundaries for human umbilical cord‐derived MSCs, cultured in chemically defined xeno‐ and serum‐free media, that yield consistent cell batches comparable to early passage cells. Two male and two female donor populations, recovered from cryostorage at mean population doubling level (mPDL) 10, were serially cultivated until replicative exhaustion (senescence). At each passage, growth kinetics, cell morphology, and transcriptome profiles were analyzed. All MSC populations displayed comparable growth trajectories through passage 9 (P9; mPDL 45) and variably approached senescence after P10 (mPDL 49). Transcription profiles of 14,500 human genes, generated by microarray, revealed a nonlinear evolution of culture‐adapted MSCs. Significant expression changes occurred only after P5 (mPDL 27) and accumulated rapidly after P9 (mPDL 45), preceding other cell aging metrics. We report that cryobanked umbilical cord‐derived MSCs can be reliably expanded to clinical human doses by P4 (mPDL 23), before significant transcriptome drift, and thus represent a mesenchymal cell source suited for clinical translation of cellular therapies. Stem Cells Translational Medicine 2019;8:945&958

Abstract Localized vascular disruption after traumatic spinal cord injury (SCI) triggers a cascade of secondary events, including inflammation, gliosis, and scarring, that can further impact recovery. In addition to immunomodulatory and neurotrophic properties, mesenchymal stromal cells (MSCs) possess pericytic characteristics. These features make MSCs an ideal candidate for acute cell therapy targeting vascular disruption, which could reduce the severity of secondary injury, enhance tissue preservation and repair, and ultimately promote functional recovery. A moderately severe cervical clip compression/contusion injury was induced at C7‐T1 in adult female rats, followed by an intravenous tail vein infusion 1 hour post‐SCI of (a) term‐birth human umbilical cord perivascular cells (HUCPVCs); (b) first‐trimester human umbilical cord perivascular cells (FTM HUCPVCs); (c) adult bone marrow mesenchymal stem cells; or (d) vehicle control. Weekly behavioral testing was performed. Rats were sacrificed at 24 hours or 10 weeks post‐SCI and immunohistochemistry and ultrasound imaging were performed. Both term and FTM HUCPVC‐infused rats displayed improved (p

Abstract Bone morphogenetic protein 2 (BMP‐2)‐loaded collagen sponges remain the clinical standard for treatment of large bone defects when there is insufficient autograft, despite associated complications. Recent efforts to negate comorbidities have included biomaterials and gene therapy approaches to extend the duration of BMP‐2 release and activity. In this study, we compared the collagen sponge clinical standard to chondroitin sulfate glycosaminoglycan (CS‐GAG) scaffolds as a delivery vehicle for recombinant human BMP‐2 (rhBMP‐2) and rhBMP‐2 expression via human BMP‐2 gene inserted into mesenchymal stem cells (BMP‐2 MSC). We demonstrated extended release of rhBMP‐2 from CS‐GAG scaffolds compared to their collagen sponge counterparts, and further extended release from CS‐GAG gels seeded with BMP‐2 MSC. When used to treat a challenging critically sized femoral defect model in rats, both rhBMP‐2 and BMP‐2 MSC in CS‐GAG induced comparable bone formation to the rhBMP‐2 in collagen sponge, as measured by bone volume, strength, and stiffness. We conclude that CS‐GAG scaffolds are a promising delivery vehicle for controlling the release of rhBMP‐2 and to mediate the repair of critically sized segmental bone defects. Stem Cells Translational Medicine 2019;8:575–585

Abstract Esophageal anastomotic leakage (EAL) is a devastating complication for esophagectomy but the available therapies are unsatisfactory. Due to the healing effects of mesenchymal stromal cells (MSCs) and supporting capability of fibrin scaffold (FS), we evaluated the efficacy of a stem‐cell therapy for EAL by engrafting adult and autologous MSCs (AAMSCs) in FS and investigated the potential mechanism. Twenty‐one rabbits were assigned to AAMSC/FS group (n = 12) and control group (n = 9). After harvested, AAMSCs were identified and then labeled with lenti.GFP. To construct EAL model, a polyethylene tube was indwelled through the anastomosis for 1 week. A total of 2 × 106 AAMSCs in 0.2 ml FS were engrafted onto the EAL for the AAMSC/FS group, whereas FS was injected for control. Magnetic Resonance Imaging (MRI) examination was performed after 5 weeks. Esophageal tissues were harvested for macroscopic, histological analyses, Western blot, and immunohistochemistry at 8 weeks. The animal model of EAL was established successfully. MRI scanning revealed a decreased inflammation reaction in AAMSC/FS group. Accordingly, AAMSC/FS group presented a higher closure rate (83.3% vs. 11.1%, p = .02) and lower infection rate (33.3% vs. 88.9%, p = .02). Histological analyses showed the autografted MSCs resided in the injection site. Furthermore, milder inflammation responses and less collagen deposition were observed in AAMSC/FS group. Western blot and immunohistochemistry studies suggested that the therapeutic effect might be related to the secretions of IL‐10 and MMP‐9. Engrafting AAMSCs in FS could be a promising therapeutic strategy for the treatment of EAL by suppressing inflammation response and alleviating fibrosis progression. Stem Cells Translational Medicine 2019;8:548–556

Abstract Considerable effort has been directed toward deriving endothelial cells (ECs) from adipose‐derived mesenchymal stem cells (ASCs) since 2004, when it was first suggested that ECs and adipocytes share a common progenitor. While the capacity of ASCs to express endothelial markers has been repeatedly demonstrated, none constitute conclusive evidence of an endothelial phenotype as all reported markers have been detected in other, non‐endothelial cell types. In this study, quantitative phenotypic comparisons to representative EC controls were used to determine the extent of endothelial differentiation being achieved with ASCs. ASCs were harvested from human subcutaneous abdominal white adipose tissue, and their endothelial differentiation was induced using well‐established biochemical stimuli. Reverse transcription quantitative real‐time polymerase chain reaction and parallel reaction monitoring mass spectrometry were used to quantify their expression of endothelial genes and corresponding proteins, respectively. Flow cytometry was used to quantitatively assess their uptake of acetylated low‐density lipoprotein (AcLDL). Human umbilical vein, coronary artery, and dermal microvascular ECs were used as positive controls to reflect the phenotypic heterogeneity between ECs derived from different vascular beds. Biochemically conditioned ASCs were found to upregulate their expression of endothelial genes and proteins, as well as AcLDL uptake, but their abundance remained orders of magnitude lower than that observed in the EC controls despite their global proteomic heterogeneity. The findings of this investigation demonstrate the strikingly limited extent of endothelial differentiation being achieved with ASCs using well‐established biochemical stimuli, and underscore the importance of quantitative phenotypic comparisons to representative primary cell controls in studies of differentiation. Stem Cells Translational Medicine 2019;8:35–45

Bone marrow (BM)-derived mesenchymal stromal cells (MSCs) are promising candidates for cell-based therapy for several immune-mediated inflammatory diseases (IMIDs) due to their multiplicity of immunomodulatory and reparative properties and favorable safety profile. However, although preclinical data were encouraging, the clinical benefit demonstrated in clinical trials of autologous MSC transplantation in a number of conditions has been less robust. This may be explained by the growing body of evidence pointing to abnormalities of the bone marrow microenvironment in IMIDs, including impaired MSC function. However, it is not currently known whether these abnormalities arise as a cause or consequence of disease, the role they play in disease initiation and/or progression, or whether they themselves are targets for disease modification. Here, we review current knowledge about the function of the BM microenvironment in IMIDs including multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and type I diabetes, focusing on MSCs in particular. We predict that an improved understanding of disease-related changes in the bone marrow microenvironment including the role of MSCs in vivo, will yield new insights into pathophysiology and aid identification of new drug targets and optimization of cell-based therapy in IMIDs., (© The Author(s) 2023. Published by Oxford University Press.)

Abstract The promise of stem cell (SC) therapies to restore functions of damaged tissues and organs brings enormous hope to patients, their families, loved ones, and caregivers. However, limits may exist for which indications SC therapies might be useful, efficacious, and safe. Applications of innovative therapies within regulatory boundaries and within the framework of controlled clinical trials are the norm in the scientific and medical community; such a system minimizes patient risk by setting a clear and acceptable safety and efficacy profile for new therapeutics before marketing authorization. This careful clinical validation approach often takes time, which patients suffering from terminal or debilitating diseases do not have. Not validated, unproven stem cell interventions (SCI) that promise a working treatment or cure for severe diseases have therefore found their way into the patient community, and providers of such treatments often take advantage of the public's willingness to pay large amounts of money for the misguided hope of a reliable recovery from their illnesses. We conducted a review of scientific publications, clinical case reports, and mass media publications to assess the reported cases and safety incidents associated with unproven SCI. The review also analyzes the main factors that were identified as contributing to the emergence and global rise of the “stem cell tourism” phenomenon. Stem Cells Translational Medicine 2018;1–10

Familial osteochondritis dissecans (FOCD) is an inherited skeletal defect characterized by the development of large cartilage lesions in multiple joints, short stature, and early onset of severe osteoarthritis. It is associated with a heterozygous mutation in the ACAN gene, resulting in a Val‐Met replacement in the C‐type lectin domain of aggrecan. To understand the cellular pathogenesis of this condition, we studied the chondrogenic differentiation of patient bone marrow mesenchymal stromal cells (BM‐MSCs). We also looked at cartilage derived from induced pluripotent stem cells (iPSCs) generated from patient fibroblasts. Our results revealed several characteristics of the differentiated chondrocytes that help to explain the disease phenotype and susceptibility to cartilage injury. First, patient chondrogenic pellets had poor structural integrity but were rich in glycosaminoglycan. Second, it was evident that large amounts of aggrecan accumulated within the endoplasmic reticulum of chondrocytes differentiated from both BM‐MSCs and iPSCs. In turn, there was a marked absence of aggrecan in the extracellular matrix. Third, it was evident that matrix synthesis and assembly were globally dysregulated. These results highlight some of the abnormal aspects of chondrogenesis in these patient cells and help to explain the underlying cellular pathology. The results suggest that FOCD is a chondrocyte aggrecanosis with associated matrix dysregulation. The work provides a new in vitro model of osteoarthritis and cartilage degeneration based on the use of iPSCs and highlights how insights into disease phenotype and pathogenesis can be uncovered by studying differentiation of patient stem cells. Significance The isolation and study of patient stem cells and the development of methods for the generation of iPSCs have opened up exciting opportunities in understanding causes and exploring new treatments for major diseases. This technology was used to unravel the cellular phenotype in a severe form of inherited osteoarthritis, termed familial osteochondritis dissecans. The phenotypic abnormalities that give rise to cartilage lesions in these patients were able to be described via the generation of chondrocytes from bone marrow‐derived mesenchymal stromal cells and iPSCs, illustrating the extraordinary value of these approaches in disease modeling.

Spinal cord injury (SCI) is a life‐threatening condition with multifaceted complications and limited treatment options. In SCI, the initial physical trauma is closely followed by a series of secondary events, including inflammation and blood spinal cord barrier (BSCB) disruption, which further exacerbate injury. This secondary pathology is partially mediated by the systemic immune response to trauma, in which cytokine production leads to the recruitment/activation of inflammatory cells. Because early intravenous delivery of mesenchymal stromal cells (MSCs) has been shown to mitigate inflammation in various models of neurologic disease, this study aimed to assess these effects in a rat model of SCI (C7‐T1, 35‐gram clip compression) using human brain‐derived stromal cells. Quantitative polymerase chain reaction for a human‐specific DNA sequence was used to assess cell biodistribution/clearance and confirmed that only a small proportion (approximately 0.001%–0.002%) of cells are delivered to the spinal cord, with the majority residing in the lung, liver, and spleen. Intriguingly, although cell populations drastically declined in all aforementioned organs, there remained a persistent population in the spleen at 7 days. Furthermore, the cell infusion significantly increased splenic and circulating levels of interleukin‐10—a potent anti‐inflammatory cytokine. Through this suppression of the systemic inflammatory response, the cells also reduced acute spinal cord BSCB permeability, hemorrhage, and lesion volume. These early effects further translated into enhanced functional recovery and tissue sparing 10 weeks after SCI. This work demonstrates an exciting therapeutic approach whereby a minimally invasive cell‐transplantation procedure can effectively reduce secondary damage after SCI through systemic immunomodulation. Significance Central nervous system pericytes (perivascular stromal cells) have recently gained significant attention within the scientific community. In addition to being recognized as major players in neurotrauma, pericytes have been discovered to share a common origin and potentially function with traditionally defined mesenchymal stromal cells (MSCs). Although there have been several in vitro comparisons, the in vivo therapeutic application of human brain‐derived stromal cells has not been previously evaluated. This study demonstrates that these cells not only display a MSC phenotype in vitro but also have similar in vivo immunomodulatory effects after spinal cord injury that are more potent than those of non‐central nervous system tissue‐derived cells. Therefore, these cells are of great interest for therapeutic use in spinal cord injury.

Mesenchymal stromal cells (MSCs) are being exploited as gene delivery vectors for various disease and injury therapies. We provide proof‐of‐concept that engineered MSCs can provide a useful, effective platform for protection against infectious disease. Venezuelan equine encephalitis virus (VEEV) is a mosquito‐borne pathogen affecting humans and equines and can be used in bio‐warfare. No licensed vaccine or antiviral agent currently exists to combat VEEV infection in humans. Direct antibody administration (passive immunity) is an effective, but short‐lived, method of providing immediate protection against a pathogen. We compared the protective efficacy of human umbilical cord perivascular cells (HUCPVCs; a rich source of MSCs), engineered with a transgene encoding a humanized VEEV‐neutralizing antibody (anti‐VEEV), to the purified antibody. In athymic mice, the anti‐VEEV antibody had a half‐life of 3.7 days, limiting protection to 2 or 3 days after administration. In contrast, engineered HUCPVCs generated protective anti‐VEEV serum titers for 21–38 days after a single intramuscular injection. At 109 days after transplantation, 10% of the mice still had circulating anti‐VEEV antibody. The mice were protected against exposure to a lethal dose of VEEV by an intramuscular pretreatment injection with engineered HUCPVCs 24 hours or 10 days before exposure, demonstrating both rapid and prolonged immune protection. The present study is the first to describe engineered MSCs as gene delivery vehicles for passive immunity and supports their utility as antibody delivery vehicles for improved, single‐dose prophylaxis against endemic and intentionally disseminated pathogens. Significance Direct injection of monoclonal antibodies (mAbs) is an important strategy to immediately protect the recipient from a pathogen. This strategy is critical during natural outbreaks or after the intentional release of bio‐weapons. Vaccines require weeks to become effective, which is not practical for first responders immediately deployed to an infected region. However, mAb recipients often require booster shots to maintain protection, which is expensive and impractical once the first responders have been deployed. The present study has shown, for the first time, that mesenchymal stromal cells are effective gene delivery vehicles that can significantly improve mAb‐mediated immune protection in a single, intramuscular dose of engineered cells. Such a cell‐based delivery system can provide extended life‐saving protection in the event of exposure to biological threats using a more practical, single‐dose regimen.

Stem cell therapy has emerged as a new strategy for treatment of ischemic heart disease. Although umbilical cord‐derived mesenchymal stromal cells (UC‐MSCs) have been used preferentially in the acute ischemia model, data for the chronic ischemia model are lacking. In this study, we investigated the effect of UC‐MSCs originated from Wharton's jelly in the treatment of chronic myocardial ischemia in a porcine model induced by ameroid constrictor. Four weeks after ameroid constrictor placement, the surviving animals were divided randomly into two groups to undergo saline injection (n = 6) or UC‐MSC transplantation (n = 6) through the left main coronary artery. Two additional intravenous administrations of UC‐MSCs were performed in the following 2 weeks to enhance therapeutic effect. Cardiac function and perfusion were examined just before and at 4 weeks after intracoronary transplantation. The results showed that pigs with UC‐MSC transplantation exhibited significantly greater left ventricular ejection fraction compared with control animals (61.3% ± 1.3% vs. 50.3% ± 2.0%, p < .05). The systolic thickening fraction in the infarcted left ventricular wall was also improved (41.2% ± 3.3% vs. 46.2% ± 2.3%, p < .01). Additionally, the administration of UC‐MSCs promoted collateral development and myocardial perfusion. The indices of fibrosis and apoptosis were also significantly reduced. Immunofluorescence staining showed clusters of CM‐DiI‐labeled cells in the border zone, some of which expressed von Willebrand factor. These results suggest that UC‐MSC treatment improves left ventricular function, perfusion, and remodeling in a porcine model with chronic myocardial ischemia. Significance Ischemic heart disease is the leading cause of death worldwide. Many patients with chronic myocardial ischemia are not suitable for surgery and have no effective drug treatment; they are called “no‐option” patients. This study finds that umbilical cord‐derived mesenchymal stromal cells transplanted by intracoronary delivery combined with two intravenous administrations was safe and could significantly improve left ventricular function, perfusion, and remodeling in a large‐animal model of chronic myocardial ischemia, which provides a new choice for the no‐option patients. In addition, this study used clinical‐grade mesenchymal stem cells with delivery and assessment methods commonly used clinically to facilitate further clinical transformation.

Preterm neonates are susceptible to perinatal hypoxic‐ischemic brain injury, for which no treatment is available. In a preclinical animal model of hypoxic‐ischemic brain injury in ovine fetuses, we have demonstrated the neuroprotective potential of systemically administered mesenchymal stromal cells (MSCs). The mechanism of MSC treatment is unclear but suggested to be paracrine, through secretion of extracellular vesicles (EVs). Therefore, we investigated in this study the protective effects of mesenchymal stromal cell‐derived extracellular vesicles (MSC‐EVs) in a preclinical model of preterm hypoxic‐ischemic brain injury. Ovine fetuses were subjected to global hypoxia‐ischemia by transient umbilical cord occlusion, followed by in utero intravenous administration of MSC‐EVs. The therapeutic effects of MSC‐EV administration were assessed by analysis of electrophysiological parameters and histology of the brain. Systemic administration of MSC‐EVs improved brain function by reducing the total number and duration of seizures, and by preserving baroreceptor reflex sensitivity. These functional protections were accompanied by a tendency to prevent hypomyelination. Cerebral inflammation remained unaffected by the MSC‐EV treatment. Our data demonstrate that MSC‐EV treatment might provide a novel strategy to reduce the neurological sequelae following hypoxic‐ischemic injury of the preterm brain. Our study results suggest that a cell‐free preparation comprising neuroprotective MSC‐EVs could substitute MSCs in the treatment of preterm neonates with hypoxic‐ischemic brain injury, thereby circumventing the potential risks of systemic administration of living cells. Significance Bone marrow‐derived mesenchymal stromal cells (MSCs) show promise in treating hypoxic‐ischemic injury of the preterm brain. Study results suggest administration of extracellular vesicles, rather than intact MSCs, is sufficient to exert therapeutic effects and avoids potential concerns associated with administration of living cells. The therapeutic efficacy of systemically administered mesenchymal stromal cell‐derived extracellular vesicles (MSC‐EVs) on hypoxia‐ischemia‐induced injury was assessed in the preterm ovine brain. Impaired function and structural injury of the fetal brain was improved following global hypoxia‐ischemia. A cell‐free preparation of MSC‐EVs could substitute for the cellular counterpart in the treatment of preterm neonates with hypoxic‐ischemic brain injury. This may open new clinical applications for “off‐the‐shelf” interventions with MSC‐EVs.

We aim to provide an innovative, comprehensive way of mapping the profusion of stem cell‐based clinical trials registered at ClinicalTrials.gov to explore the diversity of the fields of application and the temporal complexity of the domain. We used a chord diagram and phylogenetic‐like tree visualizations to assist in data mining and knowledge discovery. The search strategy used the following terms: “stromal OR stem OR mesenchymal OR progenitor.” The Medical Subject Headings (MeSH) thesaurus was used to more finely classify diseases treated by stem cells, from large fields of application to specific diseases. Of the 5,788 trials screened, 939 were included, 51.1% of which were related to mesenchymal stem cells (MSCs). No real specificity emerged as to the therapeutic uses of the different types of stem cells. More than half the MSC studies concerned allogeneic MSCs and received more support from industry than autologous MSC studies (p < .001). Over time, the uses of cultured cells have increased greatly, particularly since 2009. Cells derived from adipose tissue are also increasingly used in trials compared with bone marrow cells. The use of adipose‐derived stromal cells was predominantly autologous (p < .001), restricted to European countries (p < .01), and supported by industry (p = .02) compared with other MSCs. Details about MeSH keywords are available at http://multireview.perso.sfr.fr/. In conclusion, mapping may reveal a lack of global strategy despite the regulations and the related costs associated with good manufacturing practices. A systematic approach to preclinical data, intended to objectively and robustly reveal the most appropriate fields with the most efficient cells, is needed. Repeated exchanges between the bench and the bedside are necessary.

Objectives: Mesenchymal stromal cells (MSCs) and low-dose interleukin-2 (IL-2) both have demonstrated efficacy in treating systemic lupus erythematosus (SLE). The aim of this study is to conduct a head-to-head comparison between the 2 treatments and provide insights for clinical applications., Methods: Lupus-prone mice were treated with umbilical cord-derived MSCs (UC-MSCs), IL-2, or a combination of UC-MSCs and IL-2, respectively. The lupus-like symptoms, renal pathology, and T-cell response were assessed 1 or 4 weeks later. Modulation of IL-2 production by MSCs on immune cells was investigated by the coculture assay. Disease activity and serum IL-2 of SLE patients were determined before and after receiving UC-MSCs., Results: Both UC-MSCs and IL-2 improved lupus symptoms in lupus-prone mice 1 week after treatment, while the effects of UC-MSCs lasted up to 4 weeks. Moreover, the UC-MSC-treated group showed better renal pathology improvement. Importantly, UC-MSCs combined with IL-2 did not provide better efficacy than UC-MSCs alone. Consistent with this, UC-MSCs alone and UC-MSCs + IL-2 resulted in similar levels of serum IL-2 and frequencies of Tregs. Neutralization of IL-2 partly reduced the promotion of Tregs by UC-MSCs, suggesting that IL-2 was involved in the upregulation of Tregs by UC-MSCs. Lastly, an increase in serum IL-2 positively correlated with the reduction of disease activity of SLE patients by UC-MSCs., Conclusion: Both the single injection of UC-MSCs and repeated IL-2 administration exerted comparable efficacy in alleviating SLE manifestations, but UC-MSCs provided sustained alleviation and showed better improvement in renal pathology., (© The Author(s) 2023. Published by Oxford University Press.)

Hypoxic ischemic encephalopathy (HIE) in neonates causes increased mortality and long-term morbidity in surviving babies. Hypothermia (HT) has improved outcomes, however, mortality remains high with ~half of surviving babies developing neurological impairment in their first years. We previously explored the use of autologous cord blood (CB) to determine if CB cells could lessen long-term damage to the brain. However, the feasibility of CB collection from sick neonates limited the utility of this approach. Allogeneic cord tissue mesenchymal stromal cells (hCT-MSC), cryopreserved and readily available, have been shown to ameliorate brain injury in animal models of HIE. We, therefore, conducted a pilot, phase I, clinical trial to test the safety and describe the preliminary efficacy of hCT-MSC in neonates with HIE. The study treated infants with moderate to severe HIE, treated with HT, with 1 or 2 doses of 2 million cells/kg/dose of hCT-MSC given intravenously. The babies were randomized to receive 1 or 2 doses with the first dose during HT and the second dose 2 months later. Babies were followed for survival and development with scoring of Bayley's at 12 postnatal months. Six neonates with moderate (4) or severe (2) HIE were enrolled. All received 1 dose of hCT-MSC during HT and 2 received a 2nd dose, 2 months later. hCT-MSC infusions were well tolerated although 5/6 babies developed low titer anti-HLA antibodies by 1 year of age. All babies survived, with average to low-average developmental assessment standard scores for ages between 12 and 17 postnatal months. Further study is warranted., (© The Author(s) 2023. Published by Oxford University Press.)

Detection of cellular senescence is important quality analytics of cell therapy products, including mesenchymal stromal cells (MSCs). However, its detection is critically limited by the lack of specific markers and the destructive assays used to read out these markers. Here, we establish a rapid, live-cell assay for detecting senescent cells in heterogeneous mesenchymal stromal cell (MSC) cultures. We report that the T2 relaxation time measured by microscale Magnetic Resonance Relaxometry, which is related to intracellular iron accumulation, correlates strongly with senescence markers in MSC cultures under diverse conditions, including different passages and donors, size-sorted MSCs by inertial spiral microfluidic device, and drug-induced senescence. In addition, the live-cell and non-destructive method presented here has general applicability to other cells and tissues and can critically advance our understanding of cellular senescence., (© The Author(s) 2023. Published by Oxford University Press.)