Tracking transplanted cells by MRI - methods and protocols.

Cell tracking by magnetic resonance imaging (MRI) is an essential tool to understand the integration and migration of transplanted cells in vivo. At present, however, techniques to visualize cell transplants in patients are fairly limited and further development of cellular MRI is needed to advance the monitoring of grafted cells. The use of contrast agents to pre-label cells prior to transplantation is currently needed as transplanted cells integrate seamlessly into existing parenchyma and hence are indistinguishable from host cells. The development of appropriate contrast agents, as well as their in vitro incorporation into cells, is key to visualizing transplanted cells in vivo. We describe here procedures regarding how the in vitro incorporation of MR contrast agents can be tested, how they might affect cellular functions and how we can determine if sufficient contrast agent has been incorporated to allow detection. Before this technique can find its clinical application, in vitro and preclinical in vivo studies need to be conducted to determine the safety and specificity of this approach.