Magnetic nano particles for Labeling Stem Cells(Health concern)

· An important aspect of successful cell transplantation is tracking and the monitoring of the grafted cells in transplant recipient.(1)

·To the screen cells in vivo,many techniques have been described using the nanoparticles(like quantum dots, pebbles and super paramagnetic iron-oxide [SPIO]nanoparticles), but exclusively SPIO nanoparticles are visualized by MRI are suitable in human medicine. SPIO nanoparticles are the negative contrast agents that will selectively shorten T2-relaxation time and hence, can be detected in tissue as a hypointense (which means dark) signal. MRI, as noninvasive method, may be then used not only to evaluate whether the cells have been successfully engrafted, but also to monitor the time course of cell migration and also their survival in targeted tissue.(1)

·This information may further help in order to optimize the process of transplantation procedure in terms of the number of the required cells, the method or site of cell administration and also the therapeutic time window after injury during which transplantation will be most effective.(1)

· Super paramagnetic iron-oxide nanoparticles usually consist of a crystalline iron oxide core and a polymer shell.(1)

·In order to prevent the aggregation, dextran is most commonly used surface coating.Dextran-coated SPIO (Super paramagnetic iron-oxide )ferumoxide nanoparticles are commercially available and have been approved as contrast agents by US FDA as Feridex® and Endorem® (or) as ultrasmall SPIO nanoparticles (Sinerem®, Combidex®).(1)

· To facilitate  uptake of nanoparticles into the cells, a common labeling approach is to combine the commercially available contrast agents and also transfection agents (for ex: Superfect, poly-L-lysine, Fugene® or protamine Lipofectamine,).(1)

·The advantage of the Endorem, as well as of carboxydextran-coated ferucarbotran  is that they have been shown to be suitable contrast agents for the purpose of  labelling rat or human MSCs ,ESCs and OECs, and don’t require use of an transfection agent, however, they have a lower labeling efficiency than newly developed coatings. many strategies for the purpose of optimizing the delivery of the magnetic nanoparticles into cells are developed, like  specific targeting and also the process of  endocytosis of nanoparticles through the use of the transferring receptors, magnetodendrimers, transduction agents such as HIV-derived TAT protein or by use of electroporation.----Tamim Hasan