Evaluation of the Therapeutic Potential of Mesenchymal Stem Cells (MSCs) in Preclinical Models of Autoimmune Diseases

Study on Preclinical Safety and Toxic Mechanism of Human Umbilical Cord Mesenchymal Stem Cells in F344RG Rats

Mesenchymal stem cells have made remarkable progress in recent years. Many studies have reported that human umbilical cord mesenchymal stem cells (hUC-MSCs) have no toxicity, but thromboembolism appeared in patients treated with hUC-MSCs. Therefore, people are still worried about the safety of clinical application. The study aims to determine the safety, potential toxic mechanism and biodistribution of hUC-MSCs. F344RG rats were given 5 or 50 million cells/kg of hUC-MSCs by single administration in compliance with Good Laboratory Practice standards. Standard toxicity was performed. RNA sequencing was then performed to explore the potential toxic mechanisms. In parallel, the biodistribution of hUC-MSCs was examined. The dose of 5 million cells/kg hUC-MSCs had no obvious toxicity on symptom, weight, food intake, hematology, serum biochemistry, urine biochemistry, cytokines, and histopathology. However, blood-tinged secretions in the urethral orifice and 20% mortality occurred at 50 million cells/kg. Disseminated intravascular coagulopathy (DIC) is the leading cause of death. hUC-MSCs significantly upregulated complement and coagulation cascade pathways gene expression, resulting in DIC. Besides, hUC-MSCs upregulated fibrinolytic system suppressor genes A2m, Serping1 and Serpinf2. hUC-MSCs survived in rats for less than 28 days, no hUC-MSC was detected in tissues outside the lungs. There was no toxicity in F344RG rats at 5 million cells/kg, but some toxicities were detected at 50 million cells/kg. hUC-MSCs significantly upregulated complement and coagulation cascade pathways, upregulated the expression of fibrinolytic system suppressor genes A2m, Serping1 and Serpinf2, to inhibit fibrinolytic system, caused DIC, which provided a new insight into the toxic mechanism of hUC-MSCs.

Mesenchymal stem cells in autoimmune disease: A systematic review and meta-analysis of pre-clinical studies

Mesenchymal Stem Cells (MSCs) are of interest in the clinic because of their immunomodulation capabilities, capacity to act upstream of inflammation, and ability to sense metabolic environments. In standard physiologic conditions, they play a role in maintaining the homeostasis of tissues and organs; however, there is evidence that they can contribute to some autoimmune diseases. Gaining a deeper understanding of the factors that transition MSCs from their physiological function to a pathological role in their native environment, and elucidating mechanisms that reduce their therapeutic relevance in regenerative medicine, is essential. We conducted a Systematic Review and Meta-Analysis of human MSCs in preclinical studies of autoimmune disease, evaluating 60 studies that included 845 patient samples and 571 control samples. MSCs from any tissue source were included, and the study was limited to four autoimmune diseases: multiple sclerosis, rheumatoid arthritis, systemic sclerosis, and lupus. We developed a novel Risk of Bias tool to determine study quality for in vitro studies. Using the International Society for Cell & Gene Therapy's criteria to define an MSC, most studies reported no difference in morphology, adhesion, cell surface markers, or differentiation into bone, fat, or cartilage when comparing control and autoimmune MSCs. However, there were reported differences in proliferation. Additionally, 308 biomolecules were differentially expressed, and the abilities to migrate, invade, and form capillaries were decreased. The findings from this study could help to explain the pathogenic mechanisms of autoimmune disease and potentially lead to improved MSC-based therapeutic applications.

Wound healing potential of Cystoseira/mesenchymal stem cells in immunosuppressed rats supported by overwhelming immuno-inflammatory crosstalk

Wound healing, one of the most intricate and dynamic processes of the body, maintains skin integrity following trauma. One of the main issues that still exists is impaired wound healing, particularly for immunosuppressed patients. Recently, natural products from marine environments have been employed in wound-repairing activities. This work investigates the mesenchymal stem cells in the combined capacity of the bone marrow (BMMSC) for wound healing and Cystoseira sp. Algae extract in immunosuppressed rats. High-resolution liquid chromatography / MS investigation of Cystoseira extract revealed the prevalence of fatty acids that have wound-soothing potential. From constructed PPI network for wound healing and further analysis through molecular docking and molecular dynamics (MD) simulation experiments suggested that cystalgerone metabolite may be responsible for the wound healing-promoting effect of Cystoseira extract. According to the CD marker characterization of the BMMSC, 98.21% of them expressed CD90, and 97.1% expressed CD105. Sixteen d after immunity suppression (by 40 mg/kg hydrocortisone daily), an incision was made in the dorsal skin of the rat. The treatments were applied for 16 d and samples were taken from the tested groups on the 8th, 14th, and 16th days. The BMMSCs / Cystoseira group showed significantly improved wound closure, thickness, density of new layers, and skin elasticity than the control group (p < 0.001). The BMMSCs / Cystoseira combination significantly reduced the oxidative indicators, pro-inflammatory cytokines, and immune markers, according to the RT-PCR gene expression study. In order to delve deeper into the complex interconnections among wound healing-related biological targets and pinpoint key factors in this complex process, we engaged in network pharmacology and computational research. Subsequently, we conducted a comprehensive computational analysis, including reverse docking, free energy (ΔG) computation, and molecular dynamics simulations, on the molecular structures of the annotated compounds. The purpose of this investigation was to identify potential new targets for these chemicals as well as any potential interactions they may have with different signaling pathways related to the wound healing process. Our research indicates that the primary compounds of Cystoseira holds potential wound healing therapeutic activity. Although more safety testing and clinical studies are required, the combination has great potential for regenerative medicine and could be a revolutionary advance in the healing of the wounds of immunosuppressed patients.

Umbilical Cord-Derived Mesenchymal Stem Cells Attenuate S100-Induced Autoimmune Hepatitis via Modulating Th1 and Th17 Cell Responses in Mice

Currently, the first-line treatment for autoimmune hepatitis (AIH) is still the combination of glucocorticoids or immunosuppressants. However, hormone and immunosuppressive therapy can cause serious side effects, such as Cushing syndrome and bone marrow suppression. Previous studies reported on the applicability and safety of mesenchymal stem cells (MSCs) to ameliorate liver inflammation and fibrosis. However, the characteristics of MSCs sources directly contribute to the different conclusions on the mechanisms underlying MSC-mediated immunoregulation. Bone marrow-derived MSCs can exert an immunosuppression effect to ameliorate the S100-induced AIH model by inhibiting several proinflammatory cytokines and upregulating of PD-L1 in liver tissue. It is not clear whether human umbilical cord-derived MSCs (hUC-MSCs) could directly inhibit liver inflammation and ultimately alleviate the dysfunction of hepatocytes in the AIH model. First, hUC-MSCs were extracted from umbilical cord tissue, and the basic biological properties and multilineage differentiation potential were examined. Second, 1 × 106 hUC-MSCs were administered intravenously to AIH mice. At the peak of the disease, serum levels of alanine aminotransferase and aspartate aminotransferase and pathologic damage to liver tissue were measured to evaluate liver function and degree of inflammation. We also observed that the infiltration of CD4+ T cells in the liver was significantly reduced. Furthermore, the frequency of the splenic IFNγ- and IL-17A- producing CD4+ T cells were also significantly decreased, while we only observed an increasing trend in Treg cells in liver tissue. Third, an RNA sequencing analysis of liver tissue was performed, which showed that in the UC-MSC-treated group, the transcriptional profiles of inflammation-related signaling pathways were significantly negatively regulated compared to those of phosphate-buffered saline-treated mice. Collectively, these findings indicated the potential of hUC-MSC to suppress immune responses in immune anomaly mediated liver disease, thus offering a potential clinical option to improve AIH.

Human Bone Marrow-Derived Mesenchymal Stromal Cells Reduce the Severity of Experimental Necrotizing Enterocolitis in a Concentration-Dependent Manner

Necrotizing enterocolitis (NEC) is a devastating gut disease in preterm neonates. In NEC animal models, mesenchymal stromal cells (MSCs) administration has reduced the incidence and severity of NEC. We developed and characterized a novel mouse model of NEC to evaluate the effect of human bone marrow-derived MSCs (hBM-MSCs) in tissue regeneration and epithelial gut repair. NEC was induced in C57BL/6 mouse pups at postnatal days (PND) 3-6 by (A) gavage feeding term infant formula, (B) hypoxia/hypothermia, and (C) lipopolysaccharide. Intraperitoneal injections of PBS or two hBM-MSCs doses (0.5 × 10⁶ or 1 × 10⁶) were given on PND2. At PND 6, we harvested intestine samples from all groups. The NEC group showed an incidence of NEC of 50% compared with controls (p < 0.001). Severity of bowel damage was reduced by hBM-MSCs compared to the PBS-treated NEC group in a concentration-dependent manner, with hBM-MSCs (1 × 10⁶) inducing a NEC incidence reduction of up to 0% (p < 0.001). We showed that hBM-MSCs enhanced intestinal cell survival, preserving intestinal barrier integrity and decreasing mucosal inflammation and apoptosis. In conclusion, we established a novel NEC animal model and demonstrated that hBM-MSCs administration reduced the NEC incidence and severity in a concentration-dependent manner, enhancing intestinal barrier integrity.

High throughput screening of mesenchymal stem cell lines using deep learning

Mesenchymal stem cells (MSCs) are increasingly used as regenerative therapies for patients in the preclinical and clinical phases of various diseases. However, the main limitations of such therapies include functional heterogeneity and the lack of appropriate quality control (QC) methods for functional screening of MSC lines; thus, clinical outcomes are inconsistent. Recently, machine learning (ML)-based methods, in conjunction with single-cell morphological profiling, have been proposed as alternatives to conventional in vitro/vivo assays that evaluate MSC functions. Such methods perform in silico analyses of MSC functions by training ML algorithms to find highly nonlinear connections between MSC functions and morphology. Although such approaches are promising, they are limited in that extensive, high-content single-cell imaging is required; moreover, manually identified morphological features cannot be generalized to other experimental settings. To address these limitations, we propose an end-to-end deep learning (DL) framework for functional screening of MSC lines using live-cell microscopic images of MSC populations. We quantitatively evaluate various convolutional neural network (CNN) models and demonstrate that our method accurately classifies in vitro MSC lines to high/low multilineage differentiating stress-enduring (MUSE) cells markers from multiple donors. A total of 6,120 cell images were obtained from 8 MSC lines, and they were classified into two groups according to MUSE cell markers analyzed by immunofluorescence staining and FACS. The optimized DenseNet121 model showed area under the curve (AUC) 0.975, accuracy 0.922, F1 0.922, sensitivity 0.905, specificity 0.942, positive predictive value 0.940, and negative predictive value 0.908. Therefore, our DL-based framework is a convenient high-throughput method that could serve as an effective QC strategy in future clinical biomanufacturing processes.