Magnetic resonance mapping of transplanted endothelial progenitor cells for therapeutic neovascularization in ischemic heart disease

Tufts University, Бостон, Georgia, United States
European Journal of Cardio-Thoracic Surgery (Impact Factor: 3.3). 08/2004; 26(1):137-43. DOI: 10.1016/j.ejcts.2004.03.024
Source: PubMed


Intramyocardial transplantation of endothelial progenitor cells (EPCs) has been previously correlated with significant augmentation of vascularity and improvement of left ventricular function following myocardial ischemia. However, precise intramyocardial localization of the transplanted cells and the extent of in situ cell migration are unknown. We present a novel technique using magnetic resonance imaging (MRI) to localize transplanted EPCs in ischemic hearts.
CD34-positive cells were isolated from human peripheral blood by magnetic bead selection: CD34-positive cells adhere to CD34-negative antibody coated magnetic beads, while CD34-negative cells do not. All cells were labeled with fluorescent DiI-dye for histological localization. CD34-positive cells or CD34-negative cells (105, 1 x 106 and 2 x 106 cells) were transplanted into non-ischemic (n = 6) or ischemic myocardium (n = 2) of Sprague-Dawley rats. Rats were sacrificed 24 h after cell transplantation. The resected hearts were imaged ex vivo using 3 and 8.5 T magnets. Morphological correlation between the MRI findings and fluorescent microscopy for identification of retained CD34-positive cells was evaluated.
CD34-positive cells were identified as areas of low signal intensity on T2*-weighted images within the myocardium. These areas increased in size with the gradual increase in the echo time due to susceptibility effect. The extent of the low signal intensity at a given echo time was proportional to cell dosage. No areas of low signal were identified in the CD34-negative cell transplanted hearts. Histological localization of DiI-labeled CD34-positive cells documented a direct anatomic correlation with the localization of transplanted cells on the MRI images.
Magnetically labeled EPCs transplanted for therapeutic neovascularization in myocardial ischemia can be visualized with ex vivo MRI at high-field strengths.

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Available from: Atsuhiko Kawamoto
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    • "In particular, a subset of these cells called endothelial progenitor cells (EPCs), are involved in adult neovascularization [2]. To date, these progenitors have been shown to have an ability to mobilize from the bone-marrow into peripheral circulation, home to sites of angiogenesis, differentiate into mature endothelial cells and incorporate into the vasculature at the sites of ischemia, tumor formation and myocardial infarction [3]–[7]. "
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    Full-text · Article · Dec 2012 · PLoS ONE
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    • "A number of studies have already revealed the feasibility of in vivo tracking of the transplanted stem cells by labeling them with SPIO nanoparticles (27–29). Studies have also reported that mononuclear cells isolated from peripheral blood were tracked with MRI using colloidal superparamagnetic nanoparticles (30,31). Evidently, the low efficiency of loading these particles into the cells and the cytotoxicity of these particles limit their usage as the tracing probe (32). "
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    ABSTRACT: The transplantation of endothelial progenitor cells (EPCs) provides a novel method for the treatment of human tumors or vascular diseases. Magnetic resonance imaging (MRI) has proven to be effective in tracking transplanted stem cells by labeling the cells with superparamagnetic iron oxide (SPIO) nanoparticles. The SPIO has been used to label and track the EPCs; however, the effect of SPIO upon EPCs remains unclear on a cellular level. In the present study, EPCs were labeled with home-synthesized SPIO nanoparticles in vitro and the biological characteristics of the labeled EPCs were evaluated. The EPCs were isolated from the peripheral blood of New Zealand rabbits and cultured in fibronectin-coated culture flasks. The EPCs were labeled with home-synthesized SPIO nanoparticles at a final iron concentration of 20 µg/ml. Labeled EPCs were confirmed with transmission electron microscopy and Prussian blue staining. The quantity of iron/cell was detected by atomic absorption spectrometry. The membranous antigens of EPCs were detected by cytofluorimetric analysis. Cell viability and proliferative capability between the labeled and unlabeled EPCs were compared. The rabbit EPCs were effectively labeled and the labeling efficiency was approximately 95%. The SPIO nanoparticles were localized in the endosomal vesicles of the EPCs, which were confirmed by transmission electron microscopy. No significant differences were found in cell viability and proliferative capability between labeled and unlabeled EPCs (P>0.05). In conclusion, rabbit peripheral blood EPCs were effectively labeled by home-synthesized SPIO nanoparticles, without influencing their main biological characteristics.
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    • "Other groups apply flow cytometry for quantification of EPCs, which are positive for CD34/CD133/VEGFR2 (Massa et al., 2005; Peichev et al., 2000), CD34/CD133 (Allanore et al., 2007), or CD34/VEGFR2 (Su et al., 2010). In turn others isolate CD34 positive cells using MACS (Magnetic Activated Cell Sorting) (Weber et al., 2004) and designate these cells as EPCs. Thus, for better interpretation of the data published in the literature, there is an urgent need for standardised identification and designation methods. "
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