Increased endocytosis of magnetic nanoparticles into cancerous urothelial cells versus normal urothelial cells

Abstract

The blood-urine barrier is the tightest and most impermeable barrier in the body and as such represents a problem for intravesical drug delivery applications. Differentiation-dependent low endocytotic rate of urothelial cells has already been noted; however, the differences in endocytosis of normal and cancer urothelial cells have not been exploited yet. Here we analysed the endocytosis of rhodamine B isothiocyanate-labelled polyacrylic acid-coated cobalt ferrite nanoparticles (NPs) in biomimetic urothelial in vitro models, i.e., in highly and partially differentiated normal urothelial cells, and in cancer cells of the papillary and invasive urothelial neoplasm. We demonstrated that NPs enter papillary and invasive urothelial neoplasm cells by ruffling of the plasma membrane and engulfment of NP aggregates by macropinocytotic mechanism. Transmission electron microscopy (TEM) and spectrophotometric analyses showed that the efficacy of NPs delivery into normal urothelial cells and intercellular space is largely restricted, while it is significantly higher in cancer urothelial cells. Moreover, we showed that the quantification of fluorescent NP internalization in cells or tissues based on fluorescence detection could be misleading and overestimated without TEM analysis. Our findings contribute to the understanding of endocytosis-mediated cellular uptake of NPs in cancer urothelial cells and reveal a highly selective mechanism to distinguish cancer and normal urothelial cells.

Proposing Urothelial and Muscle In Vitro Cell Models as a Novel Approach for Assessment of Long-Term Toxicity of Nanoparticles

“…To analyze the effects of long-term NPs exposure on the cell morphology, ultrastructure, and NP intracellular fate, phase-contrast and electron microscopy were performed. In healthy cells of both highly and partially differentiated NPU cells, no internalized NPs were detected, which is consistent with previous observations that NPU cell models exhibit no endocytic activity ( Figure 5 ) [ 66 , 73 ]. Interestingly, while PEI NPs showed moderate toxicity to NPU cells, no internalized NPs were observed, indicating that PEI NP-induced plasma membrane damage, which was also found by TEM ( Figure 5 ).…”

“…L6 cells grow in a monolayer, while NPU cells grow in several layers, and when differentiated, they form a tight barrier, which is impermeable to most substances [ 64 , 65 ]. Moreover, both NPU cell models have been shown to have an extremely low endocytic rate [ 65 ], which can result in a lack of NP internalization [ 66 ], as observed by TEM ( Figure 5 ). Thus, the barrier function of NPU cells and low level of endocytosis is probably the main reason for large differences in viability compared to L6 cells.…”

Cruciferous Vegetables, Isothiocyanates, and Bladder Cancer Prevention

“…One novel therapeutic approach is via the emerging fields of nanotechnology and nanomedicine for targeted and/or enhanced drug delivery. A recent report demonstrated the ability to construct rhodamine B isothiocyanate‐labeled polyacrylic acid‐coated cobalt ferrite nanoparticles (NPs) that were endocytosed with significantly greater efficacy by cancer urothelial cells compared to normal urothelial cells suggesting a selective uptake mechanism by cancerous urothelial cells . In addition, Zhang, et al.…”

In focus in HCB

“…Lojk et al (2018) have performed a comparative analysis of the uptake by endocytosis of rhodamine B isothiocyanatelabeled polyacrylic acid-coated cobalt ferrite nanoparticles (NPs) using biomimetic urothelial in vitro models. They observed by transmission electron microscopy and spectrophotometric analysis that in contrast to differentiated normal urothelial cells, NPs are efficiently endocytozed by cells derived from human papillary (TR4 cell line) or invasive urothelial (T24 cell line) neoplasms and subsequently transported to the endo-lysosomal system.…”