Effect of mesenchymal stromal (stem) cell (MSC) transplantation in asthmatic animal models: A systematic review and meta-analysis.

BACKGROUND: Over the years, mesenchymal stromal (stem) cells (MSCs) have been pre-clinically applied in the treatment of variety kinds of diseases including asthma and chronic lung diseases. Aim of the current study was to systematically review and to conduct meta-analysis on the published studies of MSC treatment in asthma animal models. METHODS: Publications on the MSC and asthma treatment was thoroughly searched in the electronic databases. Statistical analysis was then performed using the Comprehensive Meta-Analysis software (Version 3). Effect of MSC therapy on asthma model was assessed by Hedges's g with 95% confidence intervals (95% CIs). Random effect model was used due to the heterogeneity between the studies. RESULTS: Meta-analysis of the 32 included studies showed that MSC transplantation was significantly in favor of attenuating lung injury and remodeling (Hedges's g = -9.104 ±â€¯0.951 with 95% CI: -10.969 ∼ -7.240, P < 0.001) and airway inflammation (Hedges's g = -4.146 ±â€¯0.688 with 95% CI: -5.495 ∼ -2.797, P < 0.001). The mechanism of MSC therapy in asthma seems to be regulating the balance of Th1 cytokine and Th2 cytokines (IFN-γ: Hedges's g = 4.779 ±â€¯1.408 with 95% CI: 1.099-2.725, P < 0.001; IL-4: Hedges's g = -10.781 ±â€¯1.062 with 95% CI: -12.863 ∼ -8.699, P < 0.001; IL-5: Hedges's g = -10.537 ±â€¯1.269 with 95% CI: -13.025 ∼ -8.050, P < 0.001; IL-13: Hedges's g = -6.773 ±â€¯0.788 with 95% CI: -8.318 ∼ -5.229, P < 0.001). CONCLUSION: Findings of the current systemic review suggested a potential role for MSCs in asthma treatment although it is still challenging in clinical practice. The mechanisms of MSCs in pre-clinical asthma treatment may be associated with attenuating airway inflammation through regulating Th1 and Th2 cytokines.

Preliminary evaluation of safety and migration of immune activated mesenchymal stromal cells administered by subconjunctival injection for equine recurrent uveitis.

Introduction: Equine recurrent uveitis (ERU), an immune mediated disease characterized by repeated episodes of intra-ocular inflammation, affects 25% of horses in the USA and is the most common cause of glaucoma, cataracts, and blindness. Mesenchymal stromal cells (MSCs) have immunomodulatory properties, which are upregulated by preconditioning with toll-like receptor agonists. The objective was to evaluate safety and migration of TLR-3 agonist polyinosinic, polycytidylic acid (pIC)-activated MSCs injected subconjunctivally in healthy horses prior to clinical application in horses with ERU. We hypothesized that activated allogeneic MSCs injected subconjunctivally would not induce ocular or systemic inflammation and would remain in the conjunctiva for >14 days. Methods: Bulbar subconjunctiva of two horses was injected with 10 × 106 pIC-activated (10 µg/mL, 2 h) GFP-labeled MSCs from one donor three times at two-week intervals. Vehicle (saline) control was injected in the contralateral conjunctiva. Horses received physical and ophthalmic exams [slit lamp biomicroscopy, rebound tonometry, fundic examination, and semiquantitative preclinical ocular toxicology scoring (SPOTS)] every 1-3 days. Systemic inflammation was assessed via CBC, fibrinogen, and serum amyloid A (SAA). Horses were euthanized 14 days following final injection. Full necropsy and histopathology were performed to examine ocular tissues and 36 systemic organs for MSC presence via IVIS Spectrum. Anti-GFP immunohistochemistry was performed on ocular tissues. Results: No change in physical examinations was noted. Bloodwork revealed fibrinogen 100-300 mg/dL (ref 100-400) and SAA 0-25 µg/mL (ref 0-20). Ocular effects of the subjconjucntival injection were similar between MSC and control eyes on SPOTS grading system, with conjunctival hypermia, chemosis and ocular discharge noted bilaterally, which improved without intervention within 14 days. All other ocular parameters were unaffected throughout the study. Necropsy and histopathology revealed no evidence of systemic inflammation. Ocular histopathology was similar between MSC and control eyes. Fluorescent imaging analysis did not locate MSCs. Immunohistochemistry did not identify intact MSCs in the conjunctiva, but GFP-labeled cellular components were present in conjunctival phagocytic cells. Discussion: Allogeneic pIC-activated conjunctival MSC injections were well tolerated. GFP-labeled tracking identified MSC components phagocytosed by immune cells subconjunctivally. This preliminary safety and tracking information is critical towards advancing immune conditioned cellular therapies to clinical trials in horses.

Effect of CD44 signal axis in the gain of mesenchymal stem cell surface antigens from synovial fibroblasts in vitro.

Tissue-residing mesenchymal stromal/stem cells (MSCs) have multipotent characteristics that are important for adult tissue homeostasis and tissue regeneration after injury. We previously reported that fibroblastic cells isolated from the synovial membrane in the knee joint give rise to cells with MSC characteristics in a two-dimensional culture. To explore the molecular mechanisms underlying these hyperplastic properties, we performed time-course surface antigen expression analyses during in vitro culture. Cells freshly isolated from the synovial membrane rarely contained cells that met the criteria (CD45-CD73+CD90+CD105+). However, the number of cells expressing MSC antigens increased on day 7. Flow cytometric analysis indicated that cells positive for either CD73 or CD90 were specifically derived from cells positive for CD44. CD44 expression was upregulated during culture, and CD105+ cells were specifically derived from the CD44 highly expressing cells. In addition, depletion of hyaluronic acid (HA), a major ligand of CD44, decreased the number of CD105+ cells, whereas supplementation with HA increased their number. These data suggest that intracellular signals activated by CD44 play an important role in the formation and/or maintenance of MSCs.

From Vial to Vein: Crucial Gaps in Mesenchymal Stromal Cell Clinical Trial Reporting.

Retrospective analysis of clinical trial outcomes is a vital exercise to facilitate efficient translation of cellular therapies. These analyses are particularly important for mesenchymal stem/stromal cell (MSC) products. The exquisite responsiveness of MSCs, which makes them attractive candidates for immunotherapies, is a double-edged sword; MSC clinical trials result in inconsistent outcomes that may correlate with underlying patient biology or procedural differences at trial sites. Here we review 45 North American MSC clinical trial results published between 2015 and 2021 to assess whether these reports provide sufficient information for retrospective analysis. Trial reports routinely specify the MSC tissue source, autologous or allogeneic origin and administration route. However, most methodological aspects related to cell preparation and handling immediately prior to administration are under-reported. Clinical trial reports inconsistently provide information about cryopreservation media composition, delivery vehicle, post-thaw time and storage until administration, duration of infusion, and pre-administration viability or potency assessments. In addition, there appears to be significant variability in how cell products are formulated, handled or assessed between trials. The apparent gaps in reporting, combined with high process variability, are not sufficient for retrospective analyses that could potentially identify optimal cell preparation and handling protocols that correlate with successful intra- and inter-trial outcomes. The substantial preclinical data demonstrating that cell handling affects MSC potency highlights the need for more comprehensive clinical trial reporting of MSC conditions from expansion through delivery to support development of globally standardized protocols to efficiently advance MSCs as commercial products.

miR-4732-3p in Extracellular Vesicles From Mesenchymal Stromal Cells Is Cardioprotective During Myocardial Ischemia.

Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) are an emerging alternative to cell-based therapies to treat many diseases. However, the complexity of producing homogeneous populations of EVs in sufficient amount hampers their clinical use. To address these limitations, we immortalized dental pulp-derived MSC using a human telomerase lentiviral vector and investigated the cardioprotective potential of a hypoxia-regulated EV-derived cargo microRNA, miR-4732-3p. We tested the compared the capacity of a synthetic miR-4732-3p mimic with EVs to confer protection to cardiomyocytes, fibroblasts and endothelial cells against oxygen-glucose deprivation (OGD). Results showed that OGD-induced cardiomyocytes treated with either EVs or miR-4732-3p showed prolonged spontaneous beating, lowered ROS levels, and less apoptosis. Transfection of the miR-4732-3p mimic was more effective than EVs in stimulating angiogenesis in vitro and in vivo and in reducing fibroblast differentiation upon transforming growth factor beta treatment. Finally, the miR-4732-3p mimic reduced scar tissue and preserved cardiac function when transplanted intramyocardially in infarcted nude rats. Overall, these results indicate that miR-4732-3p is regulated by hypoxia and exerts cardioprotective actions against ischemic insult, with potential application in cell-free-based therapeutic strategies.

Mesenchymal Stromal Cells for the Treatment of Graft Versus Host Disease.

Graft versus host disease (GvHD) is a life-threating complication of allogeneic hematopoietic stem cell transplantation, which is initially treated with high dose corticosteroids. Approximately 50% of acute GvHD cases are resistant to steroid treatment, and two-year mortality rates in those steroid-resistant patients exceed 80%. Chronic GvHD necessitates prolonged corticosteroid use, which is typically associated with limited efficacy and troublesome adverse effects. No agent has yet been established as an optimal second line therapy for either acute or chronic GvHD, but mesenchymal stromal cells (MSCs) have shown substantial promise. MSCs promote an immunosuppressive and immunoregulatory environment via multifactorial mechanisms, including: secretion of proteins/peptides/hormones; transfer of mitochondria; and transfer of exosomes or microvesicles containing RNA and other molecules. A large number of clinical studies have investigated MSCs from various sources as a treatment for acute and/or chronic GvHD. MSCs are generally safe and well tolerated, and most clinical studies have generated encouraging efficacy results, but response rates have varied. Confounding factors include variability in MSC donor types, production methodology and dose regimens, as well as variations in study design. It is well-established that extensive culture expansion of primary donor-derived MSCs leads to marked changes in functionality, and that there is a high level of inter-donor variability in MSC properties. However, recent manufacturing innovations may be capable of overcoming these problems. Further adequately powered prospective studies are required to confirm efficacy and establish the place of MSC therapy in the treatment of this condition.

Sonic Hedgehog Induces Mesenchymal Stromal Cell Senescence-Associated Secretory Phenotype and Chondrocyte Apoptosis in Human Osteoarthritic Cartilage.

Hedgehog (HH) signaling plays a critical role in osteoarthritis (OA) pathogenesis, but the molecular mechanism remains to be elucidated. We show here that Sonic Hedgehog (SHH) gene expression is initiated in human normal cartilage stromal cells (NCSC) and increased in OA cartilage mesenchymal stromal cells (OA-MSCs) during aging. Manifesting a reciprocal cellular distribution pattern, the SHH receptors PTCH1 and SMO and transcription factors GLI2 and GLI3 are expressed by chondrocytes (OAC) in OA cartilage. SHH autocrine treatment of osteoarthritis MSC stimulates proliferation, chondrogenesis, hypertrophy, and replicative senescence with elevated SASP gene expression including IL1B, IL6, CXCL1, and CXCL8. SHH paracrine treatment of OAC suppresses COL2A1, stimulates MMP13, and induces chondrocyte apoptosis. The OA-MSC conditioned medium recapitulates the stimulatory effects of SHH on OAC catabolism and apoptosis. SHH knock-down in OA-MSC not only inhibits catabolic and senescence marker expression in OA-MSC, but also abolishes the effect of the OA-MSC conditioned medium on OAC catabolism and apoptosis. We propose that SHH is a key mediator between OA-MSC and OA chondrocytes interaction in human OA cartilage via two mechanisms: (1) SHH mediates MSC growth and aging by activating not only its proliferation and chondrogenesis, but also low-grade inflammation and replicative senescence, and (2) SHH mediates OA-MSC-induced OAC catabolism and apoptosis by creating a pro-inflammatory microenvironment favoring tissue degeneration during OA pathogenesis.

Menatetrenone facilitates hematopoietic cell generation in a manner that is dependent on human bone marrow mesenchymal stromal/stem cells.

Vitamin K2 in the form of menatetrenone has clinical benefits for osteoporosis and cytopenia. Given the dominant role of mesenchymal-osteolineage cells in the regulation of hematopoiesis, we investigated whether menatetrenone alters the hematopoiesis-supportive capability of human bone marrow mesenchymal stromal/stem cells (BM-MSCs). Menatetrenone up-regulated fibronectin protein expression in BM-MSCs without affecting their proliferation and differentiation capabilities. In addition, menatetrenone treatment of BM-MSCs enhanced generation of the CD34+ cell population in co-cultures through acceleration of the cell cycle. This effect was associated with cell-cell interactions mediated by VLA-4 and fibronectin. This proposal was supported by cytokine array and quantitative real-time PCR analyses, in which there were no significant differences between the expression levels of hematopoiesis-associated soluble factors in naïve and menatetrenone-treated BM-MSCs. Profiling of hematopoietic cells in co-cultures with menatetrenone-treated BM-MSCs demonstrated that they included significantly more CD34+CD38+ hematopoietic progenitor cells and cells skewed toward myeloid and megakaryocytic lineages than those in co-cultures with untreated BM-MSCs. Notably, myelodysplastic syndrome-derived cells were induced to undergo apoptosis when co-cultured with BM-MSCs, and this effect was enhanced by menatetrenone. Overall, our findings indicate that pharmacological treatment with menatetrenone bestows a unique hematopoiesis-supportive capability on BM-MSCs, which may contribute to the clinical improvement of cytopenia.

Plasticity of vascular resident mesenchymal stromal cells during vascular remodeling.

Vascular remodeling is a complex and dynamic pathological process engaging many different cell types that reside within the vasculature. Mesenchymal stromal/stem cells (MSCs) refer to a heterogeneous cell population with the plasticity to differentiate toward multiple mesodermal lineages. Various types of MSC have been identified within the vascular wall that actively contribute to the vascular remodeling process such as atherosclerosis. With the advances of genetic mouse models, recent findings demonstrated the crucial roles of MSCs in the progression of vascular diseases. This review aims to provide an overview on the current knowledge of the characteristics and behavior of vascular resident MSCs under quiescence and remodeling conditions, which may lead to the development of novel therapeutic approaches for cardiovascular diseases.