Currently, spinal cord injury imposes a huge psychological and economic burden on patients and the National Health Service. The prevention, treatment, and rehabilitation of spinal cord injury have become an important topic in the field of medicine. Therefore, it is important to explore new effective therapeutic strategies based on an in-depth understanding of the underlying molecular mechanisms of spinal cord injury.

To review the research progress on the mechanism of action of mesenchymal stem cell-derived exosomes loaded with various miRNAs in improving the function of spinal cord injury, and based on the current status of clinical translation, to put forward a few thoughts and outlooks on their clinical use.

The first author searched CNKI and PubMed databases using “mesenchymal stem cells, exosomes, spinal cord injury, miRNA, pathophysiology, clinical translation, clinical trials, good manufacturing practice” as Chinese and English search terms. The types of literature included treatises and reviews, and the language types were English and Chinese. Finally, 72 papers were screened and analyzed.

(1) This article outlines the biological properties of exosomes and the advantages that they can serve as good vectors for loading miRNAs. A variety of miRNAs mediated by mesenchymal stem cell-derived exosomes mainly promote the recovery of neuronal function by regulating the expression of nerve regeneration-associated proteins, repressing RAS homologous gene family member A, activating cyclophosphoadenosine effector-binding proteins, and signaling and transcriptional activation proteins 3, and regulating phosphoinositide and tensin homologue/programmed cell death factor 4 pathways. Inflammatory responses were improved by regulating endoplasmic reticulum-to-nucleus signaling 1, expression of interferon regulatory factor 5, Toll-like receptor 4/nuclear factor-kappa B pathway, and down-regulating related pro-inflammatory factors. Angiogenesis was promoted by inhibition of germination-associated domain 1-containing EVH1 and phosphatidylinositol 3-kinase regulatory subunit 2. (2) Further comparative analyses revealed that miR-216-5p, miR-145-5p, and miR-146b improved inflammatory responses by regulating related pathways. Combining these miRNAs may produce more significant effects; hypoxic preconditioning may be a preconditioning method to increase the efficacy of exosomal therapy. (3) There are currently no clinical trials applying mesenchymal stem cell-derived exosomes to spinal cord injury, which is related to the need to meet good manufacturing practices before they can be put into clinical use. Challenges such as the need for large-scale, high-volume cell production, the lack of an efficient and uniform method for isolating exosomes, and the need to pass a strict regulatory approval mechanism prior to clinical use have impeded the clinical entry. (4) miRNAs have great potential as exosomal contents of mesenchymal stem cells in the treatment of spinal cord injury, and their mechanism of action should be explored in depth as well as accelerated to the clinical trial stage in order to provide a new and effective method for the treatment of spinal cord injury.

Radiotherapy for head and neck tumors can easily cause xerostomia, seriously affecting the quality of life of patients. In recent years, engineered stem cells and their paracrine factors have shown therapeutic potential in the repair of salivary gland injury. However, there is currently no experimental study on the application of amniotic mesenchymal stem cell-derived exosome in radiation-induced salivary gland injury.

To preliminarily explore the repair effect of exosome derived from human amniotic mesenchymal stem cells on radiation-induced submandibular gland injury.

Human amniotic mesenchymal stem cell exosomes were extracted and identified by ultrafiltration and ultracentrifugation. SD rats were randomly divided into a control group, a radiation injury group, and a radiation injury+exosome group. An in vitro model of radiation-induced submandibular gland injury was constructed using the submandibular gland tissue of SD rats irradiated with 18 Gy of radiation. One day after radiation modeling, exosome derived from human amniotic mesenchymal stem cells was injected into the submandibular gland in situ. Samples are taken at 1, 3, 7, and 14 days to detect the resting salivary flow rate. The structure of the submandibular gland tissue was observed by hematoxylin-eosin staining. The expression of glycogen particles in the submandibular gland tissue was observed by Periodic Acid-Schiff staining. Fibrosis in the submandibular gland tissue was observed by Masson staining. The secretion of salivary amylase was detected by enzyme-linked immunosorbent assay. The expression of aquaporin and tight junction proteins in submandibular gland tissue was observed by immunofluorescence staining. Real-time fluorescence quantitative PCR was used to detect the relative expression levels of aquaporins and salivary amylase mRNA in submandibular gland tissue. TUNEL assay was used to detect the apoptosis rate of submandibular gland tissues in each group.

After radiomodeling, compared with the radiation injury group, (1) hematoxylin-eosin staining observed that the submandibular gland tissue structure in the radiation injury+exosome group was restored, the nucleoli increased, the number of acinus increased, and the acinar atrophy improved. (2) Glycogen staining observed that the number and density of positive zymogen granules in the acinar cytoplasm of the radiation injury+exosome group gradually increased. (3) Masson staining results observed that the number and density of positive collagen fibers in the interstitium and around the ducts in the radiation injury+exosome group gradually decreased, the degree of fibrosis decreased, and the collagen deposition decreased. (4) The salivary flow rate in the radiation injury+exosome group increased (P < 0.05). The fluorescence intensity of aquaporin-5 was enhanced (P < 0.05) and the gene expression was significantly enhanced (P < 0.01). The fluorescence distribution of tight junction protein 4 was weakened and the fluorescence intensity decreased (P < 0.05, P < 0.01). The content of salivary amylase increased (P < 0.05) and gene expression were significantly increased (P < 0.01). The number of positive apoptotic cells decreased (P < 0.05, P < 0.01). It is indicated that local injection of exosome derived from human amniotic mesenchymal stem cells could improve the pathological morphology of submandibular gland tissue, promote saliva flow rate and amylase expression, and may play a functional repair role in radioactive submandibular gland injury by inhibiting acinar apoptosis.

With aging, the regenerative capacity and differentiation function of bone marrow mesenchymal stem cells progressively decline, reducing bone tissue repair efficacy. Thus, identifying bone marrow mesenchymal stem cell subpopulations with enhanced osteogenic potential is of significant importance for advancing bone tissue engineering.

To evaluate the osteogenic differentiation potential differences between STRO-1 positive and negative bone marrow mesenchymal stem cells under osteogenic induction conditions.

SD rat bone marrow mesenchymal stem cells were isolated and cultured. The expression of CD29, CD45, CD90, and STRO-1 was identified via flow cytometry and immunofluorescence. Immunomagnetic cell sorting was used to separate STRO-1 positive and negative bone marrow mesenchymal stem cells. The cells of two groups were subjected to osteogenic induction for 7 and 14 days. qRT-PCR and western blotting were performed to analyze differences in osteogenesis-related gene expression (Collagen I, Runt-related transcription factor 2, osteoprotegerin, and osteocalcin) and protein levels. Alizarin red staining and alkaline phosphatase staining were used to observe calcium nodule formation.

Flow cytometry showed high expression levels of CD29 and CD90 and low expression of CD45, with a positive STRO-1 expression rate of 12.8%. Immunofluorescence results were consistent with those of flow cytometry. After magnetic cell sorting, STRO-1 positive cells demonstrated a higher colony formation rate than STRO-1 negative cells. On day 14, STRO-1 positive cells showed significantly higher osteogenic differentiation potential than on day 7, with significantly elevated osteogenesis-related marker levels compared to STRO-1 negative cells (P < 0.01). The findings indicate that STRO-1 positive bone marrow mesenchymal stem cells exhibit significant advantages in osteogenic potential, providing a theoretical basis for their selection as ideal seed cells in bone tissue engineering. In future applications, they may represent a promising therapeutic approach for bone defect repair.

Remyelination in the central nervous system is a basic repair process triggered by demyelinating events, mainly through the proliferation, migration, and differentiation of oligodendrocyte precursor cells into oligodendrocytes. The process of remyelination is affected by many factors such as astrocytes, myelin debris, microglia, macrophages, endothelial cells, pericytes, T cells, and age.

Astrocytes play an important role in regulating synaptic activity, nutritional support, and tissue repair in the central nervous system. This review aims to provide potential therapeutic targets for demyelinating diseases of central nervous system by reviewing the role of astrocytes in remyelination.

A search was conducted on relevant literature collected from CNKI, PubMed, and Web of Science from 2014 to 2024. The search terms were “astrocytes, oligodendrocyte precursor cells, remyelination” in both Chinese and English. Finally, 66 articles were included after screening and summarized.

(1) The treatment of demyelinating diseases, such as multiple sclerosis, is limited to disease-modifying therapies, and there is no available method to overcome the failure of remyelination. Therefore, it is necessary to explore targets related to remyelination to promote myelin repair. (2) Remyelination is a process in which oligodendrocyte precursor cells proliferate, migrate, differentiate, and mature into oligodendrocytes, and the latter produce myelin to wrap axons to form myelin sheath. (3) Astrocytes regulate remyelination by phagocytosis of myelin debris, participating in inflammatory response, transforming into oligodendrocyte lineage cells, providing energy supply for oligodendrocyte lineage cells, releasing neurotrophic factors, and secreting extracellular matrix components. (4) The drugs screened in this paper use astrocytes and their derived factors as intervention targets to regulate the remyelination. Some drugs have satisfactory effects, but their effectiveness and safety still need more basic research and clinical trials to verify. (5) The mechanism of action of astrocytes in remyelination has not been fully elucidated, and the related molecular targets and signaling pathways can be further studied.

Numerous studies have indicated that pyroptosis plays a key role in the progression of cancer. In recent years, research has shown that pyroptosis is inextricably linked to the occurrence, development, and treatment of breast cancer. The development of effective pyroptosis-based therapeutic strategies has become a hot topic in the field of breast cancer treatment.

To comprehensively analyze the mechanisms of pyroptosis, explore the role of pyroptosis in the anti-tumor effects in breast cancer, and its potential application value in clinical treatment.

Using English search terms “pyroptosis, breast cancer, inflammasome, gasdermin, caspase, drug resistance, treatment”, PubMed database was searched for articles published from inception to August 2024. Through the preliminary screening of reading titles and abstracts, literature with poor relevance to the research content, outdated information, repeated views, and lack of authority was excluded. Finally, 121 articles were included for review.

Pyroptosis is a special form of programmed cell death that is carried out by the activation of the gasdermin family of proteins, showing potential application value in the treatment of breast cancer. Long-term or improper treatment can lead to drug resistance in cancer cells; research on the mechanism of pyroptosis helps to overcome resistance deficiencies. Pyroptosis can trigger immunogenic cell death, promoting the release of tumor-specific antigens, thereby activating the immune system and enhancing its ability to recognize and clear tumor cells. The expression levels of pyroptosis-related genes can serve as prognostic indicators for breast cancer, helping to assess patients’ treatment responses and survival periods. Research on the mechanisms of pyroptosis can provide new strategies for the treatment of breast cancer, such as targeted drugs and therapeutic methods that induce pyroptosis, contributing to the realization of personalized treatment plans for breast cancer.

Accurate early diagnosis and timely reperfusion therapy are important prerequisites for saving the lives and improving the prognosis of patients with acute myocardial infarction. Therefore, it is important to find ideal biomarkers for early diagnosis of acute myocardial infarction.

To analyze key genes associated with neutrophils by acute myocardial infarction through bioinformatics and machine learning to explore new biomarkers.

Differentially expressed genes were identified based on the Gene Expression Omnibus (GEO) database and Limma R package. Deconvolution algorithm was used to explore the immune cells infiltration level. Then, acute myocardial infarction and neutrophils-related biomarkers were screened by weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) networks, machine learning, and functional enrichment analysis. Receiver operating characteristic curve analysis was conducted to assess the diagnostic efficacy of biomarkers for acute myocardial infarction. Targeted drugs for biomarkers were screened through the STITCH and Herb database. Finally, the hospitalized patients who were first diagnosed with acute myocardial infarction in the Department of Cardiology of Affiliated Hospital of Guizhou Medical University from March to June 2023 were used as the experimental group, and the hospitalized patients who had no ischemic changes on electrocardiograms and no stenosis on coronary angiograms during the same period were used as the control group. Peripheral blood of the patients in the two groups was collected. The relative expressions of the genes were verified in the human peripheral blood samples by RT-qPCR.

(1) A total of 2 349 differentially expressed genes were obtained, and immune infiltration analysis revealed differences in immune cell scores such as B cells memory, NK cells resting, and Neutrophils between the disease and normal groups. (2) Using WGCNA, two gene modules, ME green and ME turquoise, were found to exhibit the highest correlation with neutrophil fine with acute myocardial infarction. (3) Twenty-four differential module genes were obtained after intersecting with differentially expressed genes. Functional enrichment analysis revealed that they were associated with a variety of processes such as innate immune response and defense response to bacteria. KEGG results showed that they were mainly associated with the tumor necrosis factor signaling pathway. (4) The genes mined by the machine learning algorithm took the intersection to obtain three genes, namely, S100A12, PTCH1, and LOC400499, all of which were greater than 0.7 by the area under the receiver operating characteristic curve in both the GSE48060 and GSE66360 datasets. They were considered as potential biomarkers. (5) Based on the STITCH and Herb databases, 11 target drugs were found for S100A12 and a total of 6 target drugs were found for PTCH1. (6) RT-qPCR results showed that S100A12, PTCH1, and LOC400499 were significantly differentially expressed in acute myocardial infarction patients compared with controls (P < 0.05). (7) S100A12, PTCH1, and LOC400499 may be potential diagnostic biomarkers for acute myocardial infarction, but their specificity in relation to acute myocardial infarction needs to be further investigated, in which S100A12 may be a potential target for regulating acute myocardial infarction.

Hepatocyte-like cells induced by mesenchymal stem cells are promising seed cells for liver regeneration or liver tissue engineering. The efficiency of traditional two-dimensional culture for hepatocyte induction is low, and more and more research is focused on three-dimensional culture for inducing hepatocyte differentiation.

To summarize three-dimensional culture models for the hepatic induction of mesenchymal stem cells, focus on research progress on the epigenetic regulation mechanisms of mesenchymal stem cell hepatogenic differentiation, providing a theoretical basis for improving the differentiation efficiency of mesenchymal stem cells.

Relevant articles in the PubMed and other databases such as CNKI were searched, using Chinese and English search terms “mesenchymal stem cell, 3D culture, hepatogenic differentiation, hepatocyte-like cells, epigenetics.” Additionally, the literature tracing method was employed to find some of the literature for a comprehensive review and analysis.

(1) Common three-dimensional culture models for the hepatogenic differentiation of mesenchymal stem cells currently include spheroids, biological scaffolds, bioprinting, and microfluidic chips. Each of these models has its own advantages and disadvantages in the process of inducing hepatogenic differentiation. (2) During the differentiation of mesenchymal stem cells into hepatocyte-like cells, epigenetic regulation plays a key role, primarily involving histone modification, DNA methylation, and the regulation of non-coding RNAs. (3) Under three-dimensional culture conditions, epigenetic modifications, especially histone acetylation, play an important role in promoting the hepatogenic differentiation of mesenchymal stem cells.

Long non-coding RNA (LncRNA) plays an important role in nervous system development and neurological diseases. Previous studies by the research team have demonstrated that human umbilical cord mesenchymal stem cells overexpressing erythropoietin (EPO-MSCs) under ischemic and hypoxic conditions have better neuroprotective functions and significantly activate the expression of LncRNA XIST. Research suggests that XIST is related to the pathogenesis of hypoxic-ischemic encephalopathy, but the role and mechanism of its regulation by EPO-MSCs in protecting ischemic-hypoxic neurons remain unclear.

To explore the new mechanism by which LncRNA XIST, in response to EPO-MSC signaling, affects the apoptosis of ischemic-hypoxic SH-SY5Y cells.

(1) SH-SY5Y cell lines with knockdown of LncRNA XIST (sh-XIST) and negative control (NC-XIST) were constructed through lentiviral transfection. Oxygen-glucose deprivation was used to induce ischemic-hypoxic injury in the cells. Transwell chambers were used to create a non-contact co-culture system with EPO-MSCs, sh-XIST, and NC-XIST ischemic-hypoxic SH-SY5Y cells. Cell proliferation ability was detected using the CCK-8 assay. Cell migration ability was assessed using the scratch assay, and cell apoptosis was measured by flow cytometry. (2) RNA-seq bioinformatics analysis was performed to screen for differentially expressed genes and pathways between sh-XIST and NC-XIST cell lines. Dual-luciferase experiments were used to verify the relationship between miR-124-3p and the target genes XIST and GRIN1. qRT-PCR was conducted to validate the expression levels of downstream miR-124-3p and GRIN1 genes. (3) miR-124-3p inhibitors and mimics were added to verify phenotypic changes in SH-SY5Y cells after ischemic-hypoxic injury and co-culture with EPO-MSCs.

(1) Compared with the NC-XIST group, SH-SY5Y cells in the sh-XIST group showed reduced proliferation and migration abilities and increased apoptosis after ischemic-hypoxic injury and co-culture with EPO-MSCs. (2) Dual-luciferase experiments showed that miR-124-3p interacted with the target gene XIST. SH-SY5Y cells transfected with miR-124-3p mimics and co-cultured with EPO-MSCs showed decreased apoptosis after ischemic-hypoxic injury, while SH-SY5Y cells transfected with miR-124-3p inhibitors showed increased apoptosis after co-culture with EPO-MSCs. (3) Transcriptomic sequencing and bioinformatics analysis of sh-XIST revealed significant downregulation of the neuroactive ligand-receptor pathway and the key receptor gene GRIN1 for central nervous system development. (4) Dual-luciferase experiments showed that miR-124-3p interacted with GRIN1. GRIN1 expression was significantly downregulated in the sh-XIST group after ischemic-hypoxic injury compared with the NC-XIST group. These findings indicate that LncRNA XIST promotes GRIN1 expression by upregulating miR-124-3p, thereby reducing cell apoptosis after ischemic-hypoxic injury and co-culture with EPO-MSCs and enhancing proliferation and migration. sh-XIST can block this protective function.

Extracellular vesicles have received extensive attention in the field of bone defect regeneration and repair in recent years. However, natural extracellular vesicles have deficiencies in sustained controlled release, tissue targeting, and drug loading capacity. Therefore, the introduction of engineering strategies to modify extracellular vesicles to enhance their therapeutic efficacy has become a research hotspot.

To review the role and application progress of engineered extracellular vesicles in the regeneration and repair of bone defects.

PubMed, Web of Science, CNKI, and WanFang databases were searched for relevant articles published in the past fifteen years. The search terms were “engineering, extracellular vesicles, exosomes, bone defect, bone regeneration, bone repair” in Chinese and English. After removal of poorly related, outdated, and duplicate studies by screening, 93 articles were finally included for review according to inclusion criteria.

(1) Extracellular vesicles are primarily isolated based on their density, size, immunoaffinity, and surface charge. After isolation, extracellular vesicles are characterized using imaging techniques, size- and counting-based techniques, and flow cytometry. (2) Extracellular vesicles stimulate bone regeneration by regulating immunity, angiogenesis, and proliferation and differentiation of target cells. (3) The engineering strategies of extracellular vesicles include surface modification and cargo loading. (4) The introduction of bone morphogenetic protein 2, mutant hypoxia-inducible factor-1α, vascular endothelial growth factor, miRNA and other bioactive factors into extracellular vesicles through engineering strategies can enhance their regenerative repair ability for bone defects.

Long noncoding RNA TP53TG1 (lncRNA TP53TG1) is involved in regulating the proliferation, migration, invasion, and apoptosis of various cancer cells, but there are few reports on its role in other cells.

To investigate the effects and pathways of lncRNA TP53TG1 on the proliferation and differentiation of human stem cells from the apical papilla.

Human stem cells from the apical papilla were isolated and cultured, and then transfected with lncRNA TP53TG1 overexpression lentivirus. RT-qPCR was used to detect the overexpression efficiency of lncRNA TP53TG1. Western blot assay was used to detect the relative expression levels of PI3K, AKT, ERK, P38, Smad3, and their phosphorylated proteins. Human stem cells from the apical papilla were divided into the empty lentiviral vector transfection group and the lncRNA TP53TG1 overexpression group. CCK-8 assay was used to measure the cell proliferation. Alkaline phosphatase activity was detected by alkaline phosphatase staining on day 5 of osteogenic induction. Formation of mineralized nodules was detected by alizarin red staining on day 21 of osteogenic induction. RT-qPCR was used to detect the mRNA expression levels of dentin sialophosphoprotein, Runt-related transcription factor 2, dentin matrix protein 1, and bone sialoprotein on days 3, 7, and 14 of osteogenic induction. Western blot assay was used to detect the protein expression levels of dentin sialophosphoprotein and Runt-related transcription factor 2 on days 3, 7, and 14 of osteogenic induction.

(1) RT-qPCR results showed that the lentivirus was successfully integrated into the genome of stem cells from the apical papilla. Western blot assay results showed that overexpression of lncRNA TP53TG1 up-regulated the protein levels of p-PI3K and p-AKT without affecting the expression of phosphorylated proteins in other pathways. (2) Starting from day 3 of cell culture, overexpression of lncRNA TP53TG1 significantly promoted the proliferation of stem cells from the apical papilla. (3) In the process of inducing odontogenic differentiation of stem cells from the apical papilla, overexpression of lncRNA TP53TG1 promoted the expression of odontogenic and osteogenic differentiation-related genes and proteins, significantly increased alkaline phosphatase activity and mineralized nodule formation. (4) The results show that lncRNA TP53TG1 may promote the odontogenic and osteogenic differentiation of stem cells from the apical papilla by activating the PI3K/AKT signaling pathway.