In vitro labeling of human umbilical cord mesenchymal stem cells with superparamagnetic iron oxide nanoparticles.

Human umbilical cord mesenchymal stem cells (hUC-MSCs) transplantation has been shown to promote regeneration and neuroprotection in central nervous system (CNS) injuries and neurodegenerative diseases. To develop this approach into a clinical setting it is important to be able to follow the fates of transplanted cells by noninvasive imaging. Neural precursor cells and hematopoietic stem cells can be efficiently labeled by superparamagnetic iron oxide (SPIO) nanoparticle. The purpose of our study was to prospectively evaluate the influence of SPIO on hUC-MSCs and the feasibility of tracking for hUC-MSCs by noninvasive imaging. In vitro studies demonstrated that magnetic resonance imaging (MRI) can efficiently detect low numbers of SPIO-labeled hUC-MSCs and that the intensity of the signal was proportional to the number of labeled cells. After transplantation into focal areas in adult rat spinal cord transplanted SPIO-labeled hUC-MSCs produced a hypointense signal using T2-weighted MRI in rats that persisted for up to 2 weeks. This study demonstrated the feasibility of noninvasive imaging of transplanted hUC-MSCs.