Improved Efficacy of Stem Cell Labeling for Magnetic Resonance Imaging Studies by the Use of Cationic Liposomes

Abstract

Labeling stem cells with FDA-approved superparamagnetic iron oxide particles makes it possible to track cells in vivo with magnetic resonance imaging (MRI), but high intracellular levels of iron can cause free radical formation and cytotoxicity. We hypothesized that the use of cationic liposomes would increase labeling efficiency without toxic effects. Rabbit skeletal myoblasts were labeled with iron oxide by: 1) uptake of iron oxide incorporated into cationic transfection liposomes (group I) or 2) customary endocytosis (group II). In both groups, cell proliferation and differentiation were measured and toxicity was assayed using trypan blue and ratio fluorescence microscopy with BODIPY  581/591 C 11 . The effects of the intracellular iron oxide on magnetic resonance image intensities were assessed in vitro and in vivo. Both methods resulted in uptake of iron intracellularly, yielding contrast-inducing properties on MRI images. In group II, however, incubation with iron oxide at high concentrations required for endocytosis caused generation of free radicals, a decrease in proliferation, and cell death. Cytotoxic effects in the remaining cells were still visible 24 h after incubation. Conversely, in group I, sufficient intracellular uptake for detection in vivo by MRI could be achieved at 100-fold lower concentrations of iron oxide, which resulted in a high percentage of labeled cells, high retention of the label, and no cytotoxic effects even after stressing the cells with a hypoxia-reoxygenation insult. The use of cationic liposomes for iron oxide stem cell labeling increases labeling efficiency approximately 100-fold without toxic effects. This technique results in high-contrast-inducing properties on MRI images both in vitro and in vivo and could thus be a valuable tool for tracking stem cells noninvasively.

In vivo tracking of genetically engineered, anti-HER2/neu directed natural killer cells to HER2/neu positive mammary tumors with magnetic resonance imaging

“…In previous studies, we investigated the function of hematopoietic cells more extensively and did not find any impairment of the cells due to our labeling procedure (26,39). This is in accordance with data from the literature (17,20,22,25,(40)(41)(42). The migration properties of our cells were apparently not impaired, otherwise they had not reached the tumor tissue after intravenous administration.…”

Efficient Tracking of Non-Iron-Labeled Mesenchymal Stem Cells With Serial MRI in Chronic Stroke Rats

“…14 Here we used Effectene to transfect the MRI contrast agent Gd-DTPA into stem cells, because it is relatively more efficient and less toxic than liposome, calcium phosphate, or viral vectors for transfection into primary cells. [15][16][17] There was a possibility that phagocytosed or dead transplanted cells with Gd-DTPA were detected by the MRI. However, a previous pharmacokinetic study reported that Gd-DTPA in dead cells or interstitial spaces was washed out within 24 hours.…”

Biocompatibility of Fe3O4@Au composite magnetic nanoparticles in vitro and in vivo

“…Other organs including heart, spleen, lung, kidney, and brain showed no sign of pathological changes such as edema, atrophy, steatosis, liquefaction necrosis, hyalinization, calcification, and hemosiderosis compared with the corresponding organs from the dogs in the control group ( Figure 9B-F [26][27][28] On the other hand, some researchers reported that bare Fe 3 O 4 -MNPs induced the formation of free hydroxyl radical species that reacted with intracellular constituents such as the cell's endogenous DNA, thus inhibiting cellular function and proliferation. 29,30 Moreover, it was found that exposure to dextran-or citric acid-coated Fe 3 O 4 -MNPs, of an approximate size of 31-38 nm, resulted in a dose-dependent decrease of HUVEC viability in vitro. 31 These results confirm that the toxicity of Fe 3 O 4 -MNPs affect the biocompatibility and biosafety in vitro.…”