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.

Objective To evaluate the influence of plateau hypoxia environment on the parameters of liver,renal,cardiac and metabolic functions of fighter pilots,and provide the basis for the high altitude aeromedical service.Methods Serum biochemical indices were examined and compared among 35 fighter pilots before and after 3-month high altitude training by automatic biochemistry analyzer and the results were analyzed by paired t-test.Results Compared with those before plateau training,pilots' fasting serum aspartate aminotransferase (AST),albumin (ALB),blood urea nitrogen (BUN) levels after plateau training were decreased slightly or significantly (t=2.042,10.329,2.275,P＜0.05 or ＜0.01),but were still in the normal range.Direct bilirubin (DBIL),creatinine (Cr),Beta2-microglobuline (β2-MG),lactate dehydrogenase (LDH),creatinine kinase (CK),total cholesterol (TC) were significantly higher than those before the training (t=3.792-12.454,P＜0.01),but were basically in the normal range or approaching to upper limits;uric acid (UA) was significantly higher than that before training and the normal (t=4.373,P＜0.01);alanine aminotransferase (ALT),total bilirubin (TBIL),total protein (TP),cystatin C (Cys C),glucose (Glu),triglycerides (TG) levels did not change significantly.Conclusions This study elucidated that high altitude environment can affect pilot's partial liver,renal,cardiac and metabolic functions.So the preventive measures should be strengthened.

Objective To evaluate the influence of plateau hypoxia environment on the parameters of liver,renal,cardiac and metabolic functions of fighter pilots,and provide the basis for the high altitude aeromedical service.Methods Serum biochemical indices were examined and compared among 35 fighter pilots before and after 3-month high altitude training by automatic biochemistry analyzer and the results were analyzed by paired t-test.Results Compared with those before plateau training,pilots' fasting serum aspartate aminotransferase (AST),albumin (ALB),blood urea nitrogen (BUN) levels after plateau training were decreased slightly or significantly (t=2.042,10.329,2.275,P＜0.05 or ＜0.01),but were still in the normal range.Direct bilirubin (DBIL),creatinine (Cr),Beta2-microglobuline (β2-MG),lactate dehydrogenase (LDH),creatinine kinase (CK),total cholesterol (TC) were significantly higher than those before the training (t=3.792-12.454,P＜0.01),but were basically in the normal range or approaching to upper limits;uric acid (UA) was significantly higher than that before training and the normal (t=4.373,P＜0.01);alanine aminotransferase (ALT),total bilirubin (TBIL),total protein (TP),cystatin C (Cys C),glucose (Glu),triglycerides (TG) levels did not change significantly.Conclusions This study elucidated that high altitude environment can affect pilot's partial liver,renal,cardiac and metabolic functions.So the preventive measures should be strengthened.

Objective To investigate the influence of +Gz acceleration on saliva a-amylase (SAA) of pilots,so as to assess the feasibility of taking SAA as an indicator of +Gz stress on pilots.Methods Saliva was collected from 47 pilots before and after + 6.5 Gz,+ 7.0 Gz and + 8.0 Gz centrifuge exposures.The SAA was measured by a-amylase kit (dynamic monitoring method) and chemiluminescnet immunoassay.Results ①The SAA and cortisol levels significantly changed by different +Gz exposures (F＝ 17.712,3.427,P＜0.01 or P＜0.05).Compared with that before exposures,the SAA levels measured after +6.5 Gz,+ 7.0 Gz and +8.0 Gz exposures were significantly higher (P＜0.01).The cortisol levels after +7.0 Gz and +8.0 Gz exposures were significantly higher than the baseline (P＜0.05 or 0.01).The cortisol level obtained after +8.0 Gz exposure was significantly higher than that before + 6.5 Gz,+ 7.0 Gz and + 8.0 Gz centrifuge exposures (P＜0.05).②Multivariate analysis showed that the aircraft type,pilot's age and flying hours had no influence on SAA and cortisol levels obtained after +Gz exposures.③ Pilots' cortisol levels were negatively correlated to the age and aircraft type of (r＝-0.328,-0.694,P＜0.05) but positively correlated to flying hours and +Gz level (r＝0.466,0.141,P＜0.05).SAA was positively correlated to +Gz level (r＝0.354,P＜0.01).④The levels of cortisol and SAA had less correlation either before or after +Gz exposure.Conclusions SAA elevates sensitivity with +Gz stress increase and quickly returns to baseline.So we can conclude that SAA could be a valid indicator of +Gz stress.

Objective To investigate the influence of +Gz acceleration on saliva a-amylase (SAA) of pilots,so as to assess the feasibility of taking SAA as an indicator of +Gz stress on pilots.Methods Saliva was collected from 47 pilots before and after + 6.5 Gz,+ 7.0 Gz and + 8.0 Gz centrifuge exposures.The SAA was measured by a-amylase kit (dynamic monitoring method) and chemiluminescnet immunoassay.Results ①The SAA and cortisol levels significantly changed by different +Gz exposures (F＝ 17.712,3.427,P＜0.01 or P＜0.05).Compared with that before exposures,the SAA levels measured after +6.5 Gz,+ 7.0 Gz and +8.0 Gz exposures were significantly higher (P＜0.01).The cortisol levels after +7.0 Gz and +8.0 Gz exposures were significantly higher than the baseline (P＜0.05 or 0.01).The cortisol level obtained after +8.0 Gz exposure was significantly higher than that before + 6.5 Gz,+ 7.0 Gz and + 8.0 Gz centrifuge exposures (P＜0.05).②Multivariate analysis showed that the aircraft type,pilot's age and flying hours had no influence on SAA and cortisol levels obtained after +Gz exposures.③ Pilots' cortisol levels were negatively correlated to the age and aircraft type of (r＝-0.328,-0.694,P＜0.05) but positively correlated to flying hours and +Gz level (r＝0.466,0.141,P＜0.05).SAA was positively correlated to +Gz level (r＝0.354,P＜0.01).④The levels of cortisol and SAA had less correlation either before or after +Gz exposure.Conclusions SAA elevates sensitivity with +Gz stress increase and quickly returns to baseline.So we can conclude that SAA could be a valid indicator of +Gz stress.