Improved biocompatibility and efficient labeling of neural stem cells with poly(L-lysine)-coated maghemite nanoparticles

Abstract

Summary Background: Cell tracking is a powerful tool to understand cellular migration, dynamics, homing and function of stem cell transplants. Nanoparticles represent possible stem cell tracers, but they differ in cellular uptake and side effects. Their properties can be modified by coating with different biocompatible polymers. To test if a coating polymer, poly(L-lysine), can improve the biocompatibility of nanoparticles applied to neural stem cells, poly(L-lysine)-coated maghemite nanoparticles were prepared and characterized. We evaluated their cellular uptake, the mechanism of internalization, cytotoxicity, viability and proliferation of neural stem cells, and compared them to the commercially available dextran-coated nanomag®-D-spio nanoparticles. Results: Light microscopy of Prussian blue staining revealed a concentration-dependent intracellular uptake of iron oxide in neural stem cells. The methyl thiazolyl tetrazolium assay and the calcein acetoxymethyl ester/propidium iodide assay demonstrated that poly(L-lysine)-coated maghemite nanoparticles scored better than nanomag®-D-spio in cell labeling efficiency, viability and proliferation of neural stem cells. Cytochalasine D blocked the cellular uptake of nanoparticles indicating an actin-dependent process, such as macropinocytosis, to be the internalization mechanism for both nanoparticle types. Finally, immunocytochemistry analysis of neural stem cells after treatment with poly(L-lysine)-coated maghemite and nanomag®-D-spio nanoparticles showed that they preserve their identity as neural stem cells and their potential to differentiate into all three major neural cell types (neurons, astrocytes and oligodendrocytes). Conclusion: Improved biocompatibility and efficient cell labeling makes poly(L-lysine)-coated maghemite nanoparticles appropriate candidates for future neural stem cell in vivo tracking studies.

D-mannose-Coating of Maghemite Nanoparticles Improved Labeling of Neural Stem Cells and Allowed Their Visualization by ex vivo MRI after Transplantation in the Mouse Brain

“…It should be noted that the effects were comparable for the same concentration of nanoparticles added to the cell medium. The labeling concentration used was consistent with previous studies that found that SPION efficiently labels stem cells without inducing cytotoxicity up to a concentration of 0.2 mg/ml 49,52,64,65 . The labeling and uptake of the D-mannose(g-Fe 2 O 3 ) nanoparticles was higher than of Uncoated(g-Fe 2 O 3 ) nanoparticles, but reaching only up to 50% cell labeling.…”

“…Neural stem cells were isolated from mouse fetuses at gestational day 14.5 (E14.5) as described previously [50][51][52] . Briefly, pregnant females were sacrificed and neural stem cells were isolated from the telencephalic wall of E14.5 fetuses by microdissection and dissociation using StemPro Accutase (Gibco by Thermo Fisher Scientific, Waltham, MA, USA).…”

Biocompatible Colloidal Suspensions Based on Magnetic Iron Oxide Nanoparticles: Synthesis, Characterization and Toxicological Profile

“…Pongrac et al demonstrated that poly(L-lysine)-coated maghemite nanoparticles after a stimulation of 48 h led to a cell viability and proliferation around 80% at a concentration of 0.2 mg·mL −1 while a concentration similar (0.03 mg·mL −1 ) with the highest concentration used in the present study (25 μg·mL −1 ) was responsible for around 5% dead neural stem cells—NSC (Pongrac et al, 2016), results that indicated a reduced degree of toxicity induced by the iron nanoparticles.…”

Interaction of poly-L-lysine coating and heparan sulfate proteoglycan on magnetic nanoparticle uptake by tumor cells

“…16,17 PLL coating of NPs undergoes similar uptake enhancement in a variety of cells. 13,[18][19][20][21] Although electrostatic interaction has been proposed, [11][12][13]15,17 the mechanism of PLL-induced internalization of NPs has not been elucidated.…”

“…Our results indicated that both free and immobilized PLL greatly enhanced MNP uptake by glioma cells, which is consistent with previous findings that PLL enhanced NP internalization by stem cells 13,[15][16][17]19 and other cells. 11,14,[16][17][18]21 TEM results demonstrated microvilli formation associated with MNP internalization, suggesting that endocytosis may involve macropinocytosis, 20 which is usually the internalization pathway of particles .200 nm. 46 In our study, the number of internalized PLL-MNPs was much lower than Dex-MNPs with PLL in the culture medium, which was probably due to the smaller quantity of immobilized PLL.…”