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Background and Objectives@#Bone marrow mesenchymal stem cells (BMSCs) show considerable promise in regenerative medicine. Many studies demonstrated that BMSCs cultured in vitro were highly heterogeneous and composed of diverse cell subpopulations, which may be the basis of their multiple biological characteristics. However, the exact cell subpopulations that make up BMSCs are still unknown. @*Methods@#and Results: In this study, we used single-cell RNA sequencing (scRNA-Seq) to divide 6,514 BMSCs into three clusters. The number and corresponding proportion of cells in clusters 1 to 3 were 3,766 (57.81%), 1,720 (26.40%), and 1,028 (15.78%). The gene expression profile and function of the cells in the same cluster were similar. The vast majority of cells expressed the markers defining BMSCs by flow cytometry and gene expression analysis. Each cluster had at least 20 differentially expressed genes (DEGs). We conducted Gene Ontology enrichment analysis on the top 20 DEGs of each cluster and found that the three clusters had different functions, which were related to self-renewal, multilineage differentiation and cytokine secretion, respectively. In addition, the function of the top 20 DEGs of each cluster was checked by the National Center for Biotechnology Information gene database to further verify our hypothesis. @*Conclusions@#This study indicated that scRNA-Seq can be used to divide BMSCs into different subpopulations, demon-strating the heterogeneity of BMSCs.
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Objective:To determine whether subpopulations may exist which are related to regulation of immunization or inflammation in bone marrow mononuclear cells (BMMNCs) from 2 elderly patients with hip fracture and whether there might be any difference in the subpopulations between them.Methods:Two elderly patients with hip fracture were enrolled in this study. Their venous blood was harvested to determine subpopulations of complement (C)3, C4, interleukins (IL)-2, IL-6, IL-10, and lymphocytes. Single cell RNA sequencing (scRNA-Seq) was used to group their BMMNCs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed of the top 20 differentially expressed genes for each subpopulation to judge the main function of each subpopulation. The subpopulations and the key genes related to regulation of immunization or inflammation were found out. The relationships were explored between subpopulations and prognosis of the patients.Results:By the venous blood indexes, IL-10 was slightly high in patient A; C3 below normal, C4 close to the lower normal limit, IL-2, IL-6 and IL-10 were significantly high, CD8 +T % was low, and CD4 +/CD8 + high in patient B. After scRNA-Seq and bioinformatics analyses, the BMMNCs in the 2 patients were divided into 5 subpopulations. GO and KEGG enrichment analyses showed that the functions of subpopulation 2 and subpopulation 4 were related to immunization or inflammation. CCL4, CCL5, LTB and CXCR4 in subpopulation 2 and C1QA, C1QB, CD14 and SPP1 in subpopulation 4 were related to the regulation of immunization or inflammation. The final prognosis of patient A was much better. The proportions of BMMNCs involved in subpopulation 2 and subpopulation 4 from patient A were higher than those from patient B [47.00% (1,431/3,045) versus 29.28% (882/3,012); 5.88% (179/3,045) versus 3.85% (116/3,012)]. Conclusions:The BMMNCs from elderly patients with hip fracture can be divided into subpopulations by scRNA-Seq. Some of the subpopulations may be related to regulation of immunization or inflammation, which may affect the post-injury immune inflammatory state and prognosis of the patients.