经犬心房外膜涂布实现外源基因在心房肌(细胞)的高效转染

A Method for Highly Effective Gene Transfer into Atrial Myocardium by "Painting" on Atrial Epicardial in Canine

心房肌高效的基因转染是一项技术难题.心房血供少、心房壁薄等原因限制了心房肌基因转染方法的发展.但心肌基因治疗作为一种研究和治疗心脏疾病的有效方法而逐渐被学者重视.本研究探讨一种经心房外膜涂抹使携带有绿色荧光蛋白(EGFP)基因的腺病毒高效靶向转染心房肌细胞方法的可行性.经犬胸骨正中开胸术,将含有一定浓度携带EGFP基因的腺病毒、胰蛋白酶和poloxamer F407的混合溶液涂抹至右心房外膜.术后经荧光显微镜观察荧光强度和实时PCR检测EGFP mRNA表达水平.EGFP荧光强度和mRNA表达水平在第1～6周呈现先增高后减低的趋势,其高峰在第3周出现;第3周右心房前壁各层心肌细胞均有EGFP表达;右心耳EGFP mRNA表达水平高于右心房前壁,右心房前壁和后壁表达水平无明显差异;房间隔的表达水平低于右心房,但明显高于左心房;心室和其它脏器如肺脏、肝脏、脾脏、骨骼肌、胃壁及小肠壁等的表达水平远低于右心房;通过HE染色及Masson's染色,第3周心肌无明显炎症反应和纤维化改变.因此,经心房外膜涂抹的方法使基因靶向转染心肌细胞具有较好的高效性、靶向性和安全性.

Gene transfer in atria myocardium with high efficiency has been technically challenging.Developing new methods for atrial gene transfer can be difficult in many aspects,such as the shortage of blood supply and the thinness of atrial wall.However,myocardial gene therapy remained to be an important approach for the investigation and treatment of cardiac disease.We explored the feasibility of casting mixture solution on the atrial epicardial to improve the efficiency and targeting in canine myocardial gene transfer.The mixture solution contained rAd-EGFP（1×109 pfu/mL）,trypsin（0.5%）and poloxamer F407（35%） and was spread on the right atrial epicardial via median sternotomy.The fluorescence intensity of atrial tissue at different transfer time points was observed by fluorescent microscopy.Real time PCR was used to analysis EGFP mRNA expression level positions from different part of the heart.HE straining was used to estimate the inflammatory and anatomical changes.Masson＇s trichrome straining was used to examine fibrosis.The EGFP mRNA expression showed an initial increase followed by a decrease with a peak at week 3,where almost every myocardial layers of right atrium anterior wall（RAAW） showed the transgene expression with the highest level at the right atrium anterior（RAA）.Similar level of EGFP expression was observed in RAAW and RAPW;and the expression in interatrial septum（IAS） was significantly lower than right atrium（RA）,but higher than that in left atrium（LA）.The lowest levels of EGFP mRNA expression was found in ventricular and other organs such as lung,liver,spleen,skeletal muscle,stomach,and small intestine,etc.（＊ P0.01 compared with RA）.No obvious inflammatory and fibrosis changes were found in RA tissues.Our gene transfer method by casting mixture solution on atrial epicardial showed potentials of high efficiency,targeting ability and safety.