Single-Cell ICP-MS in Combination with Fluorescence-Activated Cell Sorting for Investigating the Effects of Nanotransported Cisplatin(IV) Prodrugs

The combined use of fluorescence-activated cell sorting(FACS)and single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS)is reported, for the first time, in this work. It is applied to evaluatethe differences between the cellular uptake of ultrasmall iron oxidenanoparticles (FeNPs) loaded with cisplatin(IV) prodrug (FeNPs-Pt(IV))and cisplatin regarding cell viability. For this aim, FACS is appliedto separate viable, apoptotic, and necrotic A2780 ovarian cancer cellsafter exposing them to the nanotransported prodrug and cisplatin,respectively. The different sorted cell populations are individuallyanalyzed using quantitative SC-ICP-MS to address the intracellularamount of Pt. The highest Pt intracellular content occurs in the apoptoticcell population (about 2.1 fg Pt/cell) with a narrow intercellulardistribution when using FeNPs-Pt(IV) nanoprodrug and containing thelargest number of cells (75% of the total). In the case of the cisplatin-treatedcells, the highest Pt content (about 1.6 fg Pt/cell) could be determinedin the viable sorted cell population. The combined methodology, neverexplored before, permits a more accurate picture of the effect ofthe intracellular drug content together with the cell death mechanismsassociated with the free drug and the nanotransported prodrug, respectively,and opens the door to many possible single-cell experiments in sortedcell populations.

Automated summary

This study reports the combination of fluorescence-activated cell sorting (FACS) and single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS) for the first time. The method is used to evaluate the differences in cellular uptake of ultrasmall iron oxide nanoparticles (FeNPs) loaded with cisplatin (IV) prodrug (FeNPs-Pt(IV)) and cisplatin, and their effects on cell viability. FACS is used to separate different cell populations, which are then analyzed using SC-ICP-MS to determine the intracellular amount of platinum. This combined methodology provides a more accurate understanding of the intracellular drug content and cell death mechanisms associated with different drugs, and opens up possibilities for future single-cell experiments.