Dynamic Tracking of Injected Mesenchymal Stem Cells after Myocardial Infarction in Rats: A Serial 7T MRI Study

Abstract EN

Purpose.

To track the fate of micron-sized particles of iron oxide (MPIO) labeled mesenchymal stem cells (MSCs) in vivo in a rat myocardial infarction model using 7T magnetic resonance imaging (MRI) scanner.

Materials and Methods.

Male MSCs (2 × 106/50 μL) dual-labeled with MPIO and CM-DiI were injected into the infarct periphery 7 days after myocardial infarction (MI).

The control group received cell-free media injection.

The temporal stem cell location, signal intensity, and cardiac function were dynamically assessed using a 7T MRI at 24 h before transplantation (baseline), 3 days, 2 weeks, and 4 weeks after transplantation, respectively.

Results.

MR hypointensities caused by MPIOs were observed on T2⁎-weighted images at all time points after MSCs injection.

Cine-MRI showed that MSCs moderated progressive left ventricular remodeling.

Double staining for iron and CD68 revealed that most of the iron-positive cells were CD68-positive macrophages.

Real-time PCR for rat SRY gene showed the number of survival MSCs considerably decreased after transplantation.

MSC-treated hearts had significantly increased capillary density in peri-infarct region and lower cardiomyocytes apoptosis and fibrosis formation.

Conclusions.

Iron particles are not a reliable marker for in vivo tracking the long-term fate of MSCs engraftment.

Despite of poor cell retention, MSCs moderate left ventricular remodeling after MI.