Abstract:

BACKGROUND: Adipose tissue-derived stem cells (ADSCs) are promising for clinical application in cardiovascular cellular therapy. In vivo MR imaging of magnetically labeled ADSCs to track the survival and migration of implanted cells is important for clinical application and scientific research. However, to carefully evaluate the safety of any labeling method and investigate the characteristics of in vitro MR imaging is required before any clinical application.
OBJECTIVE: To label porcine ADSCs with superparamagnetic iron oxide nanoparticles (SPIO) combined with poly-l-lysine (PLL), and to explore the effects of magnetic cell labeling on cellular biological characteristics, multilineage differentiation potential, and the characteristics of in vitro 3.0T MR imaging.
METHODS: ADSCs were isolated from the subcutaneous adipose tissue of pigs and expanded in culture medium. ADSCs were incubated with the SPIO-PLL complex for 48 hours. Cell viability, proliferation and differentiation capacity to cardiomyocytes, osteogenic and adipogenic lineage between labeled and unlabeled cells were compared. Different concentrations of labeled ADSCs and the control were scanned at a clinical 3.0T MR system by using T1WI, T2WI and T2*WI sequences.
RESULTS AND CONCLUSION: Numerous intracytoplasmic iron particles stained with Prussian blue were detected in labeled cells with labeling efficiency of nearly 100%. Both labeled and unlabeled cells were able to differentiate into cardiomyocytes, adipocytes and osteocytes. The change in MR signal intensity increased at T1WI, T2WI and T2*WI along with elevation of the labeled cells concentration. The biggest and smallest change in signal intensity were observed at T2*WI and T1WI respectively. There were significant differences among the change in signal intensity at T1WI, T2WI and T2*WI for each cell concentration (P < 0.01). At least 1×10⁶/L SPIO labeled ADSCs could be detected by 3.0T MR. Our study indicated that ADSCs are more promising cells for clinical application in repairing damaged myocardium. ADSCs can be effectively labeled by SPIO-PLL complex without affecting the cell viability, proliferation and multilineage differentiation ability. Compared with T1WI and T2WI, T2*WI is the most sensitive sequence for MR tracking of SPIO labeled ADSCs. 3.0T MR is more sensitive for cellular tracking based on the advantage of higher magnetic field strength.