Single cell nanoparticle tracking to model cell cycle dynamics and compartmental inheritance

Abstract

Single cell encoding with quantum dots as live cell optical tracers for deriving proliferation parameters has been developed using modelling to investigate cell cycle and proliferative outputs of human osteosarcoma cells undergoing mitotic bypass and endocycle routing. A computer-based simulation of the evolving cell population provides information on the dilution and segregation of nanoparticle dose cell by cell division and allows quantitative assessment of patterns of division, at both single cell and including whole population level cell cycle routing, with no a-priori knowledge of the population proliferation potential. The output therefore provides a unique mitotic distribution function that represents a convolution of cell cycle kinetics (cell division) and the partitioning coefficient for the labelled cell compartment (daughter-daughter inheritance or lineage asymmetry). The current study has shown that the cellular quantum dot fluorescence reduced over time as the particles were diluted by the process of cell division and had the properties of a non-random highly asymmetric event. Asymmetric nanoparticle segregation in the endosomal compartment has major implications on cell-fate determining signaling pathways and could lead to an understanding of the origins of unique proliferation and drug-resistance characteristics within a tumour cell lineage.

The cytotoxic effects of polymer-coated quantum dots and restrictions for live cell applications

“…In a final part, the long-term follow up of cells labeled with the QDots at the non-toxic concentration was evaluated. Figure 5 shows a clear asymmetric transfer of particles upon subsequent cell divisions, which is in line with several recent reports [27,28].…”

Intracellular partitioning of cell organelles and extraneous nanoparticles during mitosis

“…The dilution of endocytosed QDs upon cell division leads to an asymmetric segregation of endosomes and thus of QDs [88]. Using a statistical model, the same group further showed that partitioning of nanoparticles upon cell division is a random and asymmetric event [89].…”

“…Gold particles < 10 nm: through NPCs [88,89] 10-20 nm: nuclear enclosure > 20 nm: nuclear exclusion Quantum dots Symmetric or asymmetric segregation within endosomes; nuclear exclusion [79,80] Iron oxide nanoparticles [87] Nonviral gene delivery particles Lipid carriers unknown [5,8,[13][14][15][16][17] Polymer carriers [5,8,12] …”

Cytosolic Delivery of Nanolabels Prevents Their Asymmetric Inheritance and Enables Extended Quantitative in Vivo Cell Imaging

“…In addition, it has been reported that nanomaterials trapped in endolysosomal vesicles are not distributed equally over daughter cells upon cell division 30,34,35 . While this process has been proposed to be a protective mechanism where the daughter cell with the highest NP load can be sacrificed in favour of the daughter cell with the lowest NP content 29,36 , recent findings show that asymmetric inheritance of vesicles is an inherent cell-biological phenomenon 37 . For quantitative cell tracking applications asymmetric inheritance of contrast agents over daughter cells is disadvantageous as it hinders accurate quantification of cell numbers over time, apart from the fact that the brightest signals are coming from cells that are suffering from the highest cytotoxicity.…”