Magneticaly labeled stem cells and magnetic resonance imaging(MRI) technology is an effective tracking method in vivo study, which has high spatial-temporal resolution. Gadolinium, which shows positive T1 signals and iron oxide showing negative T2 signals are the two often used contrast agents. The latter also include superparamagnetic iron oxide particle and ultrasmall superparamagnetic iron oxide particle. Transfection agents, e.g. poly-L-lysine and protamine sulfate，can enhance magnetical nanoparticles labeling stem cells. The biological characteristics of labeled stem cells did not seem to be altered. MRI can detect the labeled stem cells’ signals and also can track changes of signal in intensity and size with time past. In conclusion, MRI tracking magneticaly labeled stem cells represents a method for noninvasivly monitoring the existence and migration of engrafts.
Abstract： Compared with mitral valve replacement, there areseveral advantages in mitral valvuloplasty, so recently more and more sights are caught on mitral valve repair. According to different etiology, the surgeon can apply annuloplasty, triangular resection, quadrangular resection, replacement or transposition of chordae tendineae and so on to treat mitral regurgitation(MR). With the development of minimally invasive surgical technology, robotic mitral valve reconstruction evolve rapidly and percutaneous interventional therapy also commence from lab to bedside.We believe surgeons can repair MR safely and successfully in the majority of patients with proficiency in the basic techniques.