Experimental study of endothelial progenitor cells labeled with superparamagnetic iron oxide in vitro

Abstract

Abstract. Endothelial progenitor cells (EPCs) have an essential role in counteracting risk factor-induced endothelial injury and protecting against the development of vascular injury, such as myocardial infarction. Magnetic resonance imaging (MRI) was reported to be effective in tracking transplanted stem cells following cell-labeling with superparamagnetic iron oxide (SPIO) nanoparticles. SPIO has previously been used to label and track EPCs; however, the safest concentration of SPIO for labeling EPCs on a cellular level has remained to be elucidated. In addition, the optimum number of SPIO-labeled cells required to produce the highest quality magnetic resonance images has not yet been determined. In the present study, EPCs were isolated from the bone marrow of minipigs using density gradient centrifugation. Their biological activity was then studied using flow cytometric analysis. Cells were incubated at different concentrations of SPIO for different durations and then the growth curve, apoptosis, morphology and labeling efficiency of the EPCs were detected using optical and electron microscopy. T2-weighted fast spin-echo (T2WITSE) MRI of the different numbers of SPIO-labeled EPCs (35 µg/ml) were then obtained in axial and sagittal planes. The results of the present study demonstrated that EPCs were efficiently labeled with SPIO, with a labeling efficiency in each group of ~100% following incubation for 24 h. SPIO was found to be localized in the endosomal vesicles of EPCs, which was confirmed by electron microscopy. When the concentration of SPIO was <70 µg/ml, no significant differences were observed in cell viability, proliferative capability (P>0.05) and morphology between labeled and unlabeled EPCs. Furthermore, the T2WITSE signal intensity was significantly decreased in the groups of 5.0x10 5 /ml and 1.0x10 5 /ml compared with that of the control (P<0.05). In conclusion, the results of the present study indicated that 35 µg/ml was the most effective concentration of SPIO to label EPCs in vitro and acquire a high quality MRI. These findings may therefore contribute to the development of a promising novel therapeutic method for the treatment of myocardial infarction following autograft with SPIO-labeled EPCs in vivo.

Endothelial progenitor cells in the peripheral blood of patients with moyamoya disease labeled with superparamagnetic iron oxide in vitro for MRI detection

“…A concentration of 7 μg/mL alkyl-polyethylenimine 2 kDa (PEI2K) stabilized SPIO for the labeling of EPCs in a mouse lung carcinoma xenograft model ( 9 ), and a higher concentration might increase the potential for cytotoxicity. Furthermore, the activity of EPCs was not affected when the SPIO concentration was less than 70 μg/mL in the peripheral blood of healthy minipigs ( 25 ). However, this study indicated that 50 μg/mL SPIO had a significant inhibitory effect on the proliferation of MMD human peripheral blood EPCs.…”

The Effect of Uncoated SPIONs on hiPSC-Differentiated Endothelial Cells

“…However, we showed that a concentration as low as 10 µg/mL is sufficient to label and magnetically separate 100% of mature endothelial cells as well as hiPSC-ECs. In contrast, the reported labelling concentrations of coated SPION range from 20 µg/mL to 300 µg/mL [19,28].…”

Perspectives: MRI of angiogenesis

“…Thus angiogenesis can be enhanced, for example in hypoxic poorly perfused tissues, by delivery of endothelial progenitor stem cells. Tracking exogenously delivered endothelial progenitor cells can be achieved by MRI by labeling of the cells with detectable contrast media, most often iron oxide nanoparticles, prior to their delivery [97–105]. Such labeling is diluted with cell death or with cell proliferation, and thus there is an advantage to develop reporter genes that can be genetically encoded to be expressed by the cells.…”