Magnetic cell manipulation is an interesting technique which may be applied to medical applications such as cell sorting and cell retention. Cells naturally have a very weak magnetic moment and do not interact significantly with magnetic fields. However, if they are labeled with iron oxide nanoparticles or other magnetic labels, cells can be easily moved by magnets.
One application for this technique is for the isolation of stem cells, which divide very slowly. After cells are labeled with magnetic nanoparticles, they slowly lose magnetism as they divide and the label is diluted. However, cells which do not divide or divide very slowly will retain the label and remain magnetic. After a few cell growth cycles, the non-dividing cells can easily be pulled out by a magnet. We are using this technique to test the hypothesis of the existence of cancer stem cells which are responsible for tumor initiation.
Another application for labeling cells with magnetic nanoparticles is to retain cells at a certain location in the body. There is a lot of interest in using stem cells for regenerative therapy to repair damaged organs and tissues. However one of the major limitations is that stem cells introduced to the site of injury are often removed before they are able to differentiate and repair the damage. We have found that stem cells labeled with magnetic nanoparticles can be held in place by an external magnet, increasing the chance of successful tissue repair.