Experimental study of combining ultrasound targeted microbubble destruction with nuclear localization signal peptide to enhance gene transfection in treatment of canines myocardial infarction / 中华超声影像学杂志

ABSTRACT

Objective To improve the canines myocardial infarction curative effect by using ultrasound targeted microbubble destruction (UTMD) combining with nuclear localization signal(NLS) peptide to increase hAng-1 gene transfection efficiency.Methods Forty-six canines were randomly divided into 4 groups (n=10 in each group) after the models of myocardial infarction were prepared.Group A were untreated control;Group B were transfected with hAng-1;Group C were transfected with UTMD+hAng-1;Group D were transfected with UTMD+NLS nuclear localization signal+hAng-1.The therapeutic agents were intravenously injected at one week after myocardial infarction in each group,and the ultrasound were irradiated at the precardium in group C and D.①Echocardiography was used before and at one week after myocardial infarction and 28 days after gene transfection.Two-dimensional echocardiography was used to detect cardiac function,the left ventricular ejection fraction,the left ventricular wall motion and the myocardial contrast echocardiography were used to detect myocardial perfusion of all canines in the four groups.②On twenty-eight days after gene transfection,mRNA and Western Blot were used to detect the expression of hAng-1.Immunohistochemistry was used to detect capillary density of peri-infarct area and microvessel density (MVD).Masson′s trichromatic staining and gross specimen were used to evaluate the degree and the area of myocardial fibrosis.The gene transfection efficiency and the curative effect of all the four groups were evaluated and compared.Results ①Before myocardial infarction,in four groups canine ventricular wall motion and cardiac function were normal,and myocardial filling defect was not showed by myocardial contrast echocardiography.At one week after myocardial infarction,the left ventricular anterior and interval walls motion and the left ventricular ejection fraction in the four groups were significantly decreased.Myocardial contrast echocardiography showed anterior and interval walls myocardial filling defect.There was no significant difference among the four groups(P>0.05);On 28 days after gene transfection the left ventricular ejection fraction in the four group were increased in an order of group A,B,C,D,there was significant difference when comparing group C and D with other groups separately(P<0.05).Myocardial contrast echocardiography showed much contrast filling in the infarction and surrounding area in group D,a little contrast filling in group C and filling defect in group A and group B,there was significant difference when comparing group C and D with other groups separately(P<0.05).②RT-PCR and Western Blot showed the hAng-1 mRNA and protein expression in group D were higher than those in the other group.There was significant difference when comparing group C and group D with other groups separately(P<0.05).③Immunofluorescence showed the capillary densities were(4.7±1.6)/mm2,(11.2±2.8)/mm2,(70.0±6.4)/mm2 and (85.3±7.0)/mm2 in group A,group B,group C and group D.The differences were statistically significant compared group C and group D with other groups (P<0.05).④Masson′s trichromatic staining and cardiac gross specimen showed that the degree and area of myocardial fibrosis were gradually reduced in an order of group A,B,C,D.Conclusions UTMD and NLS peptide could effectively transfect hAng-1 gene and it provided a novel strategy of gene treatment for ischemic heart disease.