Insulin-like growth factor 1 induces bone mesenchymal stem cells differentiation into cardiomyocyte-like cells / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the ability and mechanism of insulin-like growth factor 1 (IGF-1) induced bone mesenchymal stem cells (BMSCs) differentiation into cardiomyocyte-like cells (CLCs).</p><p><b>METHODS</b>BMSCs were isolated and purified in vitro. BMSCs were treated with control medium and 15 ng/ml IGF-1 for 3, 7, 14 and 21 d, respectively. The expression of Troponin-T (TNT), Troponin-I (TNI) and pIGF-1R were detected by immunocytochemistry and Western blot. In another experimental setting, BMSCs were treated with control medium and 15 ng/ml IGF-1, IGF-1 antagonist I-OMe AG538 (300 nmol/L) and 300 nmol/L I-OMe AG538 + 15 ng/ml IGF-1 for 3 to 48 h, respectively. Phosphorylation status of ERK1/2 and AKT, the two downstream mediators of mitogen-activated protein kinase (MAPK) kinase and phosphatidylinositol 3-kinase (PI3K) pathways, were detected by immunocytochemistry and Western blot.</p><p><b>RESULTS</b>After 3 to 21 d exposure to IGF-1, the expression of pIGF-1R, TNT and TNI were significantly higher in IGF-1 group than those in control group, pIGF-1R peaked 14 d (all P < 0.05). After 3 and 6 h treatment, the ratio of pAKT/AKT (0.17 ± 0.03) and pERK1/2/ERK1/2 (0.06 ± 0.03) were significantly downregulated in I-OMe AG538 group compared to control group (1.00 ± 0.05) (all P < 0.05). The ratio of pAKT/AKT (1.00 ± 0.07) and pERK1/2/ERK1/2 (1.00 ± 0.09) were significantly upregulated in IGF-1 group compared to control group (0.72 ± 0.05) (all P < 0.05), but the ratio of pAKT/AKT (0.31 ± 0.10) and pERK1/2/ERK1/2 (0.39 ± 0.04) were significantly downregulated in I-OMe AG538 group compared to control group (0.63 ± 0.05) (all P < 0.05), the value of gray scale of TNT (195.06 ± 5.98) and TNI (198.32 ± 3.46) in I-OMe AG538 + IGF-1 group were significantly upregulated than that in IGF-1 group for TNT (188.70 ± 5.35) and TNI (176.10 ± 4.96) (all P < 0.05).</p><p><b>CONCLUSIONS</b>IGF-1 could induce BMSCs differentiation into CLCs in vitro by activating MAPK and PI3K signaling pathways.</p>

Overexpression of SERCA2a by gene transfer enhances myocardial systolic function in canines / 生理学报

The present study is aimed to study the effect of sarcoplasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) gene transfer on the contractile function of isolated cardiomyocytes of canines. The cardiomyocytes were isolated with collagenases. The isolated cardiac cells were divided into untransfected group, empty vector group and SERCA2a-transfected group. Recombinant adenovirus vector carrying enhanced green fluorescent protein gene was used for SERCA2a gene delivery. The expression of SERCA2a protein in cardiomyocytes was determined by Western blot. Contractile function of cardiomyocytes was measured with motion edge-detection system of single cell at 48 h after transfection. The results showed, compared with untransfected group, SERCA2a protein level, percentage of peak contraction amplitude under normal condition, percentages of peak contraction amplitude under Ca(2+) or isoproterenol stimulation, time-to-peak contraction (TTP) and time-to-50% relaxation (R50) in SERCA2a-transfected group all increased significantly. While all the above indices in empty vector group did not show any differences with those in untransfected group. These results suggest that the overexpression of SERCA2a by gene transfer may enhance the contraction function of canine myocardial cells.