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.

Download full-text


Available from: Atsuhiko Kawamoto,
  • Source
    • "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]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of these experiments was to evaluate the expression of endothelial markers, such as Tie2 and VEGFR2 in endothelial cells derived from blood mononuclear endothelial progenitor cells. Bovine mononuclear cells were isolated using separation by centrifugation and were grown in endothelial specific media supplemented with growth factors. Isolation of the whole cell population of mononuclear cells (MNC) from bovine peripheral blood gave rise to progenitor-like cells (CD45(-)) that, although morphologically similar, have different phenotypes revealed by expression of endothelial specific markers Tie2 and VEGFR2. Plating of MNCs on collagen and fibronectin gave rise to more colonies than non-coated dishes. Occasional colonies from MNC isolations had a mural cell phenotype, negative for Tie2 and VEGFR2 but positive for smooth muscle actin and PDGFRβ. Although cells expressing high levels of VEGFR2 and low levels of Tie2, and vice versa were both able to form cords on Matrigel, cells with higher expression of Tie2 migrate faster in a scratch assay than ones with lower expression of Tie2. When these different clones of cells were introduced in mice through tail vein injections, they retained an ability to home to angiogenesis occurring in a subcutaneous Matrigel plug, regardless of their Tie2/VEGFR2 receptor expression patterns, but cells with high VEGFR2/low Tie2 were more likely to be CD31 positive. Therefore, we suggest that active sites of angiogenesis (such as wounds, tumors, etc.) can attract a variety of endothelial cell precursors that may differentially express Tie2 and VEGFR2 receptors, and thus affect our interpretation of EPCs as biomarkers or therapies for vascular disease.
    PLoS ONE 12/2012; 7(12):e53385. DOI:10.1371/journal.pone.0053385 · 3.23 Impact Factor
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    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.
    Molecular Medicine Reports 05/2012; 6(2):282-6. DOI:10.3892/mmr.2012.912 · 1.55 Impact Factor
  • Source
    • "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. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Circulating endothelial progenitor cells (EPCs) in the peripheral blood of adults represent an auspicious cell source for tissue engineering of an autologous endothelium on blood-contacting implants. Novel materials biofunctionalised with EPC-specific capture molecules represent an intriguing strategy for induction of selective homing of progenitor cells. The trapped EPCs can differentiate into endothelial cells and generate a non-thrombogenic surface on artificial materials. However, the success of this process mainly depends on the use of optimised capture molecules with a high selectivity and affinity. In recent years, various biomedical engineering strategies have emerged for in situ immobilisation of patient's own stem cells on blood contacting materials. The realisation of this in vivo tissue engineering concept and generation of an endothelium on artificial surfaces could exceedingly enhance the performance of not only small calibre vascular grafts and stents, but also, in general all blood-contacting medical devices, such as heart valves, artificial lungs, hearts, kidneys, and ventricular assist devices.
    European cells & materials 01/2011; 21:157-76. · 4.89 Impact Factor
Show more