Optimization of the magnetic labeling of human neural stem cells and MRI visualization in the hemiparkinsonian rat brain

Abstract

Background: Magnetic resonance imaging is the ideal modality for non-invasive in vivo cell tracking allowing for longitudinal studies over time. Cells labeled with superparamagnetic iron oxide nanoparticles have been shown to induce sufficient contrast for in vivo magnetic resonance imaging enabling the in vivo analysis of the final location of the transplanted cells. For magnetic nanoparticles to be useful, a high internalization efficiency of the particles is required without compromising cell function, as well as validation of the magnetic nanoparticles behaviour inside the cells. Results: In this work, we report the development, optimization and validation of an efficient procedure to label human neural stem cells with commercial nanoparticles in the absence of transfection agents. Magnetic nanoparticles used here do not affect cell viability, cell morphology, cell differentiation or cell cycle dynamics. Moreover, human neural stem cells progeny labeled with magnetic nanoparticles are easily and non-invasively detected long time after transplantation in a rat model of Parkinson's disease (up to 5 months post-grafting) by magnetic resonance imaging. Conclusions: These findings support the use of commercial MNPs to track cells for short-and mid-term periods after transplantation for studies of brain cell replacement therapy. Nevertheless, long-term MR images should be interpreted with caution due to the possibility that some MNPs may be expelled from the transplanted cells and internalized by host microglial cells.

The effect of magnetic nanoparticles on neuronal differentiation of induced pluripotent stem cell-derived neural precursors

“…We did not observe any substantial differences in differentiation potential between labeled and non-labeled cells. This is in agreement with previous results on the differentiation of labeled cells in human ventral mesencephalic cells, 31 human fetal midbrainderived neural precursor, 37 SPIO-labeled human neural stem cells 28 and human fetal neural precursor cells. 45 Similarly, in iPSC-derived neural stem cells, labeling of cells with various contrast agents did not affect the differentiation potential into various types of neural precursor cells.…”

“…23,24 Comparable labeling efficiencies were shown in the labeling of neural stem cells with various types of contrast agents. [28][29][30][31] Further, we confirmed the internalization of both types of contrast agents in cell cytoplasm using TEM. Nanoparticles were present in cytoplasm in clusters surrounded by a membrane.…”

“…28 This is in agreement with in vivo experiments of SPIO-labeled neural stem cells. 29,31,37 Results from cell labeling and MR support the idea that cell labeling of iPSC-NPs both with PLL-coated γ-Fe 2 O 3 (SPION) and with CZF is sufficient to detect the cells in MR imaging in vivo. However, further experiments of in vivo models of PD will be necessary.…”

“…The relaxivity rates decreased during differentiation, which might correspond to the cell proliferation and contrast dilution also reported in other labeling studies. 28,29,31 However, this could be overcome in in vivo experiments where following transplantation in the CNS, the majority of cells differentiate and diminish their replication potential 35,36 or exit the cell cycle and retain the intracellular SPIO over a longer time period. 28 This is in agreement with in vivo experiments of SPIO-labeled neural stem cells.…”

Effects of the iron oxide nanoparticle Molday ION Rhodamine B on the viability and regenerative function of neural stem cells: relevance to clinical translation

“…In fact, several recent studies have demonstrated the efficient tracking of superparamagnetic iron oxide (SPIO)-labeled NSCs in animal models. [10][11][12][13] Nevertheless, the effects of SPIO labeling on NSC behavior and fate are not fully understood. For eventual clinical use, first, an ideal SPIO agent must not only support the uniform and long-term labeling of NSCs but also exhibit nontoxic qualities such that the intrinsic biology and function of the NSCs (which is of essence in the success of any transplantation approach) is not altered.…”