7. Techniques for "in-vivo tracking" of transplanted cells

One of the most essential and obvious steps to follow after cellular transplantation is to track down the implanted cells in host tissues. To date, several studies have reported the use of in vivo tracking system where an investigator can observe and analyze transplanted cells to evaluate their extensive status including site of cell transplantation, cellular migration, proliferation, differentiation into desired cell types, long-term self-renewal and their integration within a host tissue [140]. Using MRI technique where a superparamagnetic iron oxide works as a contrast mediator, transplanted cells can be tracked down in vivo [141]. One of a study has shown that using 3D microtopographic scaffolds, reprogrammed neuronal cells were capable of colonizing damaged neural cells to replace with transplantable cells [142]. It has been reported that transplanted MSCs, labeled with established gadolinium-based MRI contrast agent, i.e. Gadoteridol, were effectively traced via in vivo tracking in a SCI mouse model. A procedure that was employed during the in vivo tracking was established on hypo-osmotic shock that induced an osmolality-contingent permeabilization and physical alterations in cellular membrane [143]. Hence the in vivo cell tracking techniques are evolving; further development in these technologies will help to optimize future cellular transplantation therapy protocols for SCIs.
