Noninvasive Monitoring of Stem Cell Transfer for Muscle Disorders

In this study the ability of magnetodendrimers to efficiently label cultured muscle stem cells and allow for subsequent in vivo cell detection was determined. Magnetodendrimer-labeled cells exhibited normal growth rates in culture, and retained their capacity to undergo proliferation and form normal myotubes. Labeled stem cells possessed high in vivo proton relaxivities that enhanced MRI contrast properties and enabled us to noninvasively monitor the stem cells' incorporation into dystrophic muscle. Well defined regions of decreased signal intensity were observed in both T₂- and T ₁-weighted image sequences. MRI was used to longitudinally follow stem cell dynamics in dystrophic muscle with in-plane resolutions on the order of a single muscle fiber (22 × 43 μm²). Regions of decreased signal intensity were well correlated with iron accumulation and other histochemical markers of stem cell incorporation. We concluded that this technique may be useful for continuous noninvasive readouts of stem cell transfer, replacing sequential muscle biopsies and tissue harvesting.