Intracellular Drug Uptake-A Comparison of Single Cell Measurements Using ToF-SIMS Imaging and Quantification from...

Area of Science:

• Pharmacology
• Analytical Chemistry
• Cell Biology

Background:

• Single-cell analysis is critical for understanding drug uptake heterogeneity.
• Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a label-free imaging technique.
• Previous studies demonstrated ToF-SIMS for amiodarone imaging in rat macrophages.

Purpose of the Study:

• To evaluate the applicability of ToF-SIMS for amiodarone imaging in additional cell lines relevant to drug discovery.
• To investigate single-cell amiodarone uptake variations across different cell types.
• To compare ToF-SIMS single-cell data with population-based quantitative methods.

Main Methods:

• Time-of-flight secondary ion mass spectrometry (ToF-SIMS) for label-free imaging of amiodarone.
• Utilized human embryonic kidney (HEK293), cervical cancer (HeLa), and liver cancer (HepG2) cell lines.
• Liquid chromatography-tandem mass spectrometry (LC/MS/MS) for population-level drug quantification.
• Flow cytometry for cell counting.

Main Results:

• ToF-SIMS successfully imaged amiodarone in HEK293, HeLa, and HepG2 cells, extending its utility.
• Significant inter- and intra-cell line variability in amiodarone uptake was observed.
• NR8383 and HepG2 cells showed higher amiodarone uptake (2.38 and 2.60 pg/cell) compared to HeLa and HEK293 (0.43 and 0.36 pg/cell).
• ToF-SIMS and LC/MS/MS results generally agreed for NR8383, HepG2, and HEK293, but discrepancies were noted for HeLa cells.

Conclusions:

• ToF-SIMS is a valuable tool for visualizing and quantifying label-free, single-cell drug distribution in various cell types.
• Observed drug uptake heterogeneity highlights the importance of single-cell analysis in drug discovery.
• Further investigation is needed to understand the discrepancies between ToF-SIMS and LC/MS/MS for specific cell lines like HeLa.