Non-invasive analysis of myoblast transplants in rodent cardiac muscle.

Background: Magnetic resonance imaging (MRI) of magnetically labeled stem cells is a non-invasive approach that can provide images with high spatial resolution. We evaluated the ability of a commercially available, Food and Drug Administration (FDA) approved contrast agent to allow the monitoring of myoblast transplants in the rodent heart.

Methods And Results: Primary rat myoblasts were efficiently labeled by incubation with ferumoxide-polycation complexes and labeled cells retained their normal capacity to generate mature myotubes. Intra-cellular iron-oxide accumulation resulted in MRI contrast changes, allowing for three-dimensional, non-invasive detection of labeled cells in the rodent myocardium. Histological analysis of hearts injected with labeled myoblasts or control, non-viable myoblasts revealed that areas of MRI contrast changes corresponded to iron contained within engrafted myotubes and scavenger cells up to two months post-injection.

Conclusions: The high sensitivity of MR imaging will allow for non-invasive studies of cardiac stem cell migration and homing. Additional techniques are in development to non-invasively determine stem cell engraftment rates, viability and differentiation.