The main function of mitochondrial fusion protein 1 （Mfn1） and mitochondrial fusion protein 2 （Mfn2） was originally thought to be just regulating the fusion of mitochondrial outer membrane. But in recent years，many studies on these two proteins show that they are involved in many important cellular physiological processes including proliferation，apoptosis，necrosis and regulation of respiratory function and oxidative metabolism. There are many aspects of the influenceof Mfn1 and Mfn2 on cardiomyocyte，which have not been thoroughly studied yet，sometimes with even contradictoryconclusions. But these two proteins definitely have significant impact on the growth，development and physiological functionof cardiomyocyte. To investigate the function and mechanism of Mfn1 and Mfn2 in various physiological processes of cardiomyocyte is of great significance for in vitro studies of physiological functions of cardiomyocyte and technological development of myocardial tissue engineering and transplantation in vivo. This article mainly focuses on recent research progress of the influence of Mfn1 and Mfn2 on various physiological functions of cardiomyocyte.
The establishing of myocardial tissue engineering techniques not only solve a series of issues that generate in cell and tissue transplantation after myocardial infarction, but also create a platform for selecting better materials and transplantation techniques. However, both experimental animal studies and recent clinical trials indicate that current transplantation techniques still have many defects, mainly including lack of suitable seed cells, low survival rate and low differentiation rate after transplantation. In this context, extracellular matrix （ECM）, as myocardial tissue engineering scaffold materials, has gained increasing attention and become a frontier and focus of medical research in recent years. ECM is no longer merely regarded as a scaffold or a tissue, but plays an important role in providing essential signals to influence major intracellular pathways such as cell proliferation, differentiation and metabolism. The involved models of ECM can be classified into following types：natural biological scaffold materials, synthetic polymer scaffold materials and composite scaffold materials with more balanced physical and biological properties. This review mainly introduces research progress of ECM in myocardial tissue engineering and ECM materials.
Objective To analyze the preoperative risk factors of atrial fibrillation (AF) in patients with coronary artery disease after coronary artery bypass grafting (CABG). Methods From September 2007 to April 2008, the clinical information of 226 patients who underwent onpump coronary artery bypass grafting(CABG)or offpump coronary artery bypass grafting(OPCAB) was collected. The patients were divided into nonAF group and AF group according to whether AF lasted more than 5 mins in 3 days after operation. Ultrasonic cardiography (UCG) and clinical information of preoperation in two groups were analyzed. Results Twentyfour（10.6%） patients had AF after operation. There were more patients whose left atrial diameter gt;35 mm in AF group than that in nonAF group ［41.7%（10）vs. 22.3% (45),χ2=4.380, P=0.036）］, more patients had mitral regurgitation in AF group than that in nonAF group ［37.5%（9） vs. 17.3% (35),χ2=5.568, P=0.018）］, more patients had left main coronary artery involvement in AF group than that in nonAF group ［33.3% (8) vs.12.4% (25),χ2=7.560,P=0.006］, and patients in AF group were older than those in nonAF group ［65.7±9.5 years vs. 60.1±10.1 years,t=-2.724,P=0.010］. In univariate analysis, in terms of preoperative clinical indexs such as the aged, mitral regurgitation, left atrial diameter, left mainm coronary artery involvement, and postoperative clinical indexs such as ventilatory time （χ2=4.190，P=0.040）, electrocardiogram (ECG) monitoring time（χ2=5.948，P=0.015）, hospitalization expense（χ2=4.110，P=0.043）, there were significant differences between 2 groups. Conclusion Risk factors such as the aged, mitral regurgitation, left atrial diameter and left main coronary artery involvement are related to AF after CABG. Clinical index, ECG and echocardiography are helpful to predict AF, and can provide better prevention and treatment, and reduce the rate of AF.