新型主动脉瓣反流小鼠模型的构建与评价

Establishment and evaluation of a novel aortic valve regurgitation model in mice

目的构建新型主动脉瓣反流小鼠模型并评价其心脏离心性肥大程度。研究对象选择15只C57BL/6J雄性小鼠,体重24.0~34.0 g,分为假手术组(7只)和主动脉瓣反流组(8只)。干预措施小鼠麻醉后,将包含金属丝的塑料导管插入主动脉反流组小鼠的右颈总动脉行进至主动脉瓣膜处,用金属丝刺穿主动脉瓣,直到脉冲多普勒超声在主动脉弓中显示出小鼠心脏舒张期逆行血流峰值速度达到0.4 m/s左右。最后取出导管和金属丝,结扎右颈总动脉。相应的假手术小鼠行类似操作,但不破坏主动脉瓣。观测指标及测量方法术后2周所有存活小鼠均通过超声心动图以及心脏病理切片评估心脏肥大程度。超声心动图检测室壁厚度和心腔内径。超声检查后对小鼠行安乐死取心脏,测量心脏重量/体重比,行病理切片观察心脏大小和检测心肌细胞横截面积。结果与假手术组小鼠相比,主动脉瓣反流组小鼠主动脉弓血流在舒张期出现明显反流(峰值速度为0.4 m/s),提示造模成功。反流组小鼠心脏重量/体重比增加[(8.61±0.09)vs.(4.21±0.07),P<0.05],并且出现明显离心性心脏肥大特征:左心室舒张末期内径增大[(4.79±0.05)mmvs.(3.69±0.02)mm,P<0.05],左心室舒张末期后壁厚度增加[(0.94±0.01)mmvs.(0.75±0.01)mm,P<0.05]。病理切片结果显示心肌细胞横截面积增加[(321.2±16.2)μm^(2)vs.(242.8±12.9)μm^(2),P<0.05]。结论该新型主动脉瓣反流小鼠模型成功出现心脏离心性肥大,可作为心脏容量超负荷研究的理想模式动物。

Objective To establish a novel aortic regurgitation model in mice and evaluate whether the model was successful.Subjects C57BL/6J male mice(body weight 24.0~34.0 g)were divided into sham operation group(n=7)and aortic valve regurgitation group(n=8).Interventions After the mice were anesthetized,a plastic catheter containing a metal wire was inserted into the right common carotid artery.Then aortic valves were punctured by the metal wire until the Doppler ultrasound showed significant diastolic retrograde flow(around 0.4 m/s)in the aortic arch.Finally,the catheter together with the metal wire,was withdrawn,and the right common carotid artery was enclosed.The corresponding sham-operated mice underwent the same procedure without the puncture of the aortic valves.Main Outcomes and Measurements All mice were evaluated by echocardiography and histological analysis 2 weeks after surgery.Echocardiography was employed to examine ventricular wall thickness and inner diameter.After echocardiographic examination,the mice were euthanized.Hearts were excised to measure heart weight-tobody weight ratio.Histological analyses were used to verify ventricular size and cross sectional area of cardiomyocytes.Results Compared with the Sham operation group,the AR group showed prominently regurgitant flow in the aortic arches(peak velocity was around 0.4 m/s),suggesting successful establishment of AR model.The AR mice demonstrated remarkably increased heart weight-to-body weight ratio[(8.61±0.09)vs.(4.21±0.07),P<0.05]and eccentric cardiac hypertrophy,with increased left ventricular end-diastolic diameter[(4.79±0.05)mm vs.(3.69±0.02)mm,P<0.05]and left ventricular end-diastolic wall thickness[(0.94±0.01)mm vs.(0.75±0.01)mm,P<0.05].Histological analysis indicated the cross sectional area of cardiomyocytes was moderately augmented[(321.2±16.2)μm^(2)vs.(242.8±12.9)μm^(2),P<0.05].Conclusion The novel aortic regurgitation mouse model successfully shows eccentric cardiac hypertrophy,suggesting its potential application for the research of cardiac volume overload.