BACKGROUND:Bone marrow mesenchymal stem cells (BMSCs) have been induced to differentiate into cardiomyocyte-like cells in vitro.OBJECTIVE:To explore the association between GATA-4, Nkx-2.5 and α-myosin heavy chain (α-MHC) expression and cell morphological changes and structure formation in the process of BMSCs differentiation into cardiomyocyte-like cells.METHODS:By using myocardial lysate, BMSCs were induced to differentiate into cardiomyocytes.Immunocytochemistry staining was used to detect cardiac troponin T (cTnT) and connexin43, for the identification of cardiomyocytes. In the process of directional differentiation, RT-PCR was used to detect the expression of GATA-4,Nkx2.5 and α-MHC.RESULTS AND CONCLUSION:During the directional differentiation of BMSCs, the cells were changed from long fusiform to short rod, forming protrusions that were interconnected to form mesh-like, bamboo-like or myotube-like structure. When the cells were interconnected like a bamboo, cTNT and connexin43 positive cells were visible, and then the number of positive cells increased with the presence of myotube-like structure. RT-PCR results showed that during the induced directional differentiation of BMSCs, GATA-4, Nkx2.5 and α-MHC mRNA levels increased continuously. When interconnected cells formed a mesh-like structure, GATA-4 expression reached the peak and then kept a high level. When adjacent cells were fused into a myotube-like structure, α-MHC reached the peak. Additionally, the expression of Nkx2.5presented a time-dependent increase trend. Overall, during the induced differentiation of BMSCs into cardiomyocyte-like cells, the expression of cardiomyocyte specific genes, characterized by temporality and spatiality, is related to the changes of cell morphology and special structure formation.

Objective: To examine the regulatory effect of ginsenoside Rg1 (G-Rg1) on endoplasmic reticulum stress and its effect on hepatocellular apoptosis in carbon tetrachloride (CCl₄)-induced acute liver failure (ALF). Methods: Forty healthy, adult male C57/BL mice were randomly divided into normal saline control (NS) group, G-Rg1 blank control (G-Rg1) group, CCl₄ model (CCl₄) group, and G-Rg1 preventive treatment (CCl₄+G-Rg1) group, and an ALF mouse model was established by CCl₄ induction. Blood and liver specimens were collected from all mice upon sacrifice at 12 hours post-intraperitoneal injection. Serum alanine aminotransferase (ALT), serum aspartate aminotransferase (AST) and total bilirubin (TBil) levels were determined using commercial test kits. The mRNA expression of glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP) was measured using real-time PCR. The protein expression of GRP78, CHOP, caspase12, and caspase3 were measured by Western blot. Histological changes in the liver were assessed by hematoxylin-eosin staining, and the expression of GRP78 and caspase3 was detected by immunohistochemistry. Hepatocyte apoptosis was determined using terminal transferase dUTP nick end labeling. Quantitative data were analyzed using one-way ANOVA, and subsequent pairwise comparisons were performed using the LSD-t method. Results: Serum ALT, AST, and TBil levels in the CCl₄+G-Rg1 group were significantly reduced compared with those in the CCl₄ group (ALT: 691.30 ± 108.06 U/L vs 980.66 ± 110.29 U/L, F = 365.07, P < 0.05; AST: 195.40 ± 15.41 U/L vs 319.44 ± 89.32 U/L, F = 115.64, P < 0.05; TBil: 1.09 ± 0.11 mg/dl vs 1.56 ± 0.12 mg/dl, F = 211.29, P < 0.05). The relative mRNA expression of GRP78 and CHOP was significantly lower in the CCl₄ + G-Rg1 group than in the CCl₄ group (P < 0.05). The relative protein expression of caspase3, GRP78, caspase12, and CHOP was significantly reduced to different extents in the CCl₄+G-Rg1 group compared with those in the CCl4 group (P < 0.05). The CCl₄ + G-Rg1 group showed reduced liver tissue degeneration and necrosis compared with the CCl₄ group. Furthermore, the CCl₄+G-Rg1 group showed significantly fewer brown granules in the liver than the CCl4 group (P < 0.05), indicating that G-Rg1 preventive treatment reduced CCl₄-induced hepatocyte apoptosis. Conclusion G-Rg1 prophylaxis can inhibit inflammation and reduce hepatocyte necrosis and apoptosis during CCl₄-induced ALF. Its mechanism may involve the suppression of endoplasmic reticulum stress-related signaling molecules to alleviate hepatocyte endoplasmic reticulum stress and apoptosis. The results of this study suggest that G-Rg1 may inhibit liver inflammation and hepatocyte apoptosis through multiple targets to protect liver function.

BACKGROUND: Bone marrow mesenchymal stem cells have been induced into islet-like cell mass in vitro. However, little researches reported on the morphological changes of cells, the types of endocrine cells in the islet-like cell mass and their relationships. OBJECTIVE: To investigate the morphological changes of cells in the differentiation of bone marrow mesenchymal stem cells into islet-like structure and to explore the composition and distribution of endocrine cells. METHODS: Passage 3 bone marrow mesenchymal stem cells growing well were cultured and expanded until the cell colonies occupies 80% of the bottom of the culture bottle, and the pancreatic tissue lysate was added for continuous induction. Dithizone staining was used to screen the islet-like cell mass directly differentiated from bone marrow mesenchymal stem cells. The types and distribution of endocrine cells were identified by Mallory staining. Expressions of insulin, C-peptide, glucagon and somatostatin protein were detected by immunofluorescence cytochemical staining. RESULTS AND CONCLUSION: (1) Dithizone staining showed that the number of positive cells was increased over the induction time. (2) Mallory staining showed the red α-like cells were located in the periphery of the islet-like cell mass, the yellow β-like cells located in the center and periphery, and the light blue fibroblasts were distributed around the cell mass. (3) Immunofluorescence staining showed insulin, C-peptide, glucagon and somatostatin positive cells in the islet-like cell mass. To conclude, under certain microenvironment, bone marrow mesenchymal stem cells can differentiate into islet-like structures which containing α, β, δ-like cells, and are surrounded by fibroblast-like cells.

Objective: To explore the effects of dendritic epidermal T cells (DETC) on proliferation and apoptosis of epidermal cells in wound margin of mice and its effects on wound healing. Methods: Twenty-eight healthy specific pathogen free (SPF) C57BL/6 wild-type (WT) male mice aged 8-12 weeks and 60 SPF T lymphocyte receptor δ-knockout (TCR δ^-/-) male mice aged 8-12 weeks were selected to conduct the following experiments. (1) Eight WT mice were selected to isolate epidermal cells and primarily culture DETC according to the random number table. Morphological observation and purity identification of DETC by flow cytometer were detected immediately after culture and on culture day (CD) 15 and 30, respectively. (2) According to the random number table, 5 WT mice and 5 TCR δ^-/- mice were selected and enrolled into WT control group and TCR δ^-/- group. Round full-thickness skin defect with diameter of 6 mm was made on the back of each mouse. The wound healing condition was observed immediately after injury and on post injury day (PID) 2, 4, 6, 8, 10, and the percentage of residual wound area was calculated. (3) Mice were selected to group and reproduce model of full-thickness skin defect as in experiment (2). On PID 3, the tissue of wound margin was collected for hematoxylin eosin staining, and the length of new epithelium was measured. (4) Mice were selected to group and reproduce model of full-thickness skin defect as in experiment (2). On PID 3, epidermal tissue of wound margin was collected to determine expression of proliferating cell nuclear antigen (PCNA) using Western blotting for evaluation of proliferation of epidermal cell. (5) Mice were selected to group and reproduce model of full-thickness skin defect as in experiment (2). On PID 3, epidermal tissue of wound margin was selected and digested into single-cell suspension, and apoptosis of cells was detected by flow cytometer. (6) Forty TCR δ^-/- mice were selected to carry out the same treatment as in experiments (2)-(5). According to the random number table, these mice were enrolled into TCR δ^-/- control group and TCR δ^-/-+ DETC group, with 5 mice in each group for each experiment. Round full-thickness skin defect was made on the back of each mouse. DETC in the number of 1×10⁵ (dissolution in 100 μL phosphate with buffer purity above 90%) were injected through multiple points of wound margin of mice in TCR δ^-/-+ DETC group immediately after injury, and equal volume of phosphate buffer was injected into mice of TCR δ^-/- control group with the same method as above. Data were processed with one-way analysis of variance for repeated measurement, t test, and Bonferroni correction. Results: (1) Along with the culture time elapse, the number of dendritic structures of DETC increased gradually. The percentage of T lymphocytes was 4.67% and 94.1% of these T lymphocytes were DETC. The purity of DETC on CD 15 was 18.50% and the purity of DETC on CD 30 was 98.70%. (2) Immediately after injury, the wound healing condition of mice in WT control group and TCR δ^-/- group was similar. The wound healing speed of mice in TCR δ^-/- group was slower than that in WT control group on PID 2-10. The percentages of residual wound area of mice in TCR δ^-/- group on PID 2, 4, 6, 8, and 10 were increased significantly compared with those in WT control group (t=3.492, 4.425, 4.170, 4.780, 7.318, P<0.01). (3) The length of new epithelium of mice in TCR δ^-/- group on PID 3 was (359 ± 15) μm, which was obviously shorter than that in WT control group [(462±26) μm, t=3.462, P<0.01]. (4) Immediately after injury, wound condition of mice in TCR δ^-/-+ DETC group and TCR δ^-/- control group was similar. Compared with TCR δ^-/-+ DETC group, the wound healing speed of mice in TCR δ^-/- control group were obviously slower on PID 2-10. The percentages of residual wound area of mice in TCR δ^-/-+ DETC group on PID 2, 4, 6, 8, and 10 were decreased significantly compared with those in TCR δ^-/- control group (t=2.308, 3.725, 2.698, 3.707, 6.093, P<0.05 or P<0.01). (5) On PID 3, the length of new epithelium of mice in TCR δ^-/-+ DETC group was (465±31) μm, which was obviously longer than that in TCR δ^-/- control group [(375±21) μm, t=2.390, P<0.05]. (6) On PID 3, PCNA expression of epidermal cell in wound margin of mice in TCR δ^-/- group was 1.25±0.04, which was obviously lower than that in WT control group (2.01±0.09, t=7.415, P<0.01). (7) On PID 3, PCNA expression of epidermal cell in wound margin of mice in TCR δ^-/-+ DETC group was 1.62±0.08, which was significantly higher than that in TCR δ^-/- control group (1.05±0.14, t=3.561, P<0.05). (8) On PID 3, apoptosis rate of epidermal cell in wound margin of mice in TCR δ^-/- group was (16.1±1.4)%, which was higher than that in WT control group [(8.1±0.6)%, t=5.363, P<0.01]. (9) On PID 3, apoptosis rate of epidermal cell in wound margin of mice in TCR δ^-/-+ DETC group was (11.4±1.0)%, which was obviously lower than that in TCR δ^-/- control group [(15.4±1.4)%, t=2.377, P<0.05]. Conclusions DETC participates in the process of wound healing though promoting the proliferation of epidermal cells in wound margin and inhibit the apoptosis of these cells.

Objectives To analyze the studies about predicting COVID-19 by math models, to provide evidences and experiences to reduce the hazard of COVID-19. Methods PubMed, CNKI and other databases were searched for studies involving math models of COVID-19, and the studies were compared with each other and the real data. Results A total of 21 publications were included. SIR, SEIR and other models were used to predict the prevalence and evaluate the interventions. The results were predicted by SEIR^+CAQ model were the closest to the actual situation. And the control measures have effectively restrained COVID-19. Conclusion Characteristics of COVID-19 and prevention measures should be concerned, when predicting the epidemic trend of COVID-19.