ABSTRACT
This study examined the change of p16(INK4a) and PNCA protein expression in myocardium after injection of hIGF-1 gene modified skeletal myoblasts into post-infarction rats. HIGF-1 gene modified skeletal myoblasts (hIGF-1-myoblasts) were injected into hind limb muscles of 18 post-infraction rats (experimental group). Primary-myoblasts were injected into 18 post-infraction rats (control group) and 12 non-infarction rats (sham group). Expression of p16(INK4a) and PCNA protein in myocardiums were separately detected immunocytochemically 1, 2 and 4 weeks after the inuection. The level of hIGF-1 and rIGF-1 protein in serum and myocardium were detected by enzyme-linked immunosorbent assay (ELISA). Compared with the sham group, the percentage of p16(INK4a) and PCNA positive cells reached a peak after 1 week in the control group and the experimental group (P0.05). ELISA analysis disclosed that the myocardium level of rIGF-1 protein increased gradually in the controls and especially in the experimental group (P<0.01). The serum level of rIGF-1 decreased significantly in post-infraction rats, but these conditions were improved in the experimental group (P<0.01). The hIGF-1 protein in serum and myocardium were detected from the 1st week to the 4th week in the experimental group. Statistical analysis revealed significant associations of myocardium level of hIGF-1 protein with expression of p16(INK4a) and PCNA protein (r=-0.323, P<0.05; r=0.647, P<0.01). It is concluded that genetically hIGF-1-myoblast provides a means for constant synthesis and release of hIGF-1. It could not only improve the expression of rIGF-1 and PCNA protein in myocardium, but also suppress the expression of p16(INK4a) protein for 30 days in post-infraction rats. Myoblasts-mediated IGF-1 gene therapy may provide a new alternative for the clinical treatment of heart failure.
ABSTRACT
AIM:As a factor that can improve cell growth,there are few studies about the effect of insulin-like growth factor Ⅰ(IGF-Ⅰ) on the apoptosis of endothelial cell.The study investigated the inhibition and mechanism of IGF-Ⅰ on the apoptosis of human umbilical vein endothelial cells(HUVEC) induced by oxidized low density lipoprotein(ox-LDL).METHODS:The experiment was performed in the Institute of Cardiovascular Disease,Union Hospital of Huazhong University of Science and Technology from December 2006 to July 2007.①Fresh human umbilical cord was obtained(the informed consent) to isolate and culture HUVECs.The cells were divided into four groups.Except the control group,HUVEC cells were cultured with IGF-Ⅰ(1?10-9mmol/L),ox-LDL(200 mg/L)+IGF-Ⅰ(1?10-9mmol/L),and ox-LDL(200 mg/L),respectively after cultured for 24 hours.②Cell viability was determined by MTT assay,morphology and apoptosis by DAPI fluorescence staining,and expressions of caspase-3 were analyzed.RESULTS:①Ox-LDL could significantly inhibit HUVEC cell proliferation.After treated with both IGF-Ⅰand ox-LDL,the cell proliferation increased obviously compared with the cells treated with ox-LDL(P