MeXpose - A modular imaging pipeline for the quantitative assessment of cellular metal bioaccumulation

We introduce MeXpose, an imaging pipeline for single-cell metallomics by laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOFMS). MeXpose is designed for mechanistic studies on metal exposure unravelling cellular phenotypes and tissue level characteristics of metal bioaccumulation. MeXpose leverages the high-resolution capabilities of low-dispersion laser ablation setups, a standardised approach to quantitative bioimaging, and the toolbox of immunohistochemistry using metal-labelled antibodies for cellular phenotyping. MeXpose further offers the full scope of single-cell metallomics via an extended mass range accessible through ICP-TOFMS instrumentation (covering isotopes from m/z 14-256) and integration of a complete image analysis workflow. This enables studying quantitative metal accumulation in phenotypically characterized tissue at cellular resolution. Metal amounts in the sub-fg range per cell can be absolutely quantified. As a showcase, an ex vivo human skin model exposed to cobalt chloride (CoCl2) was investigated. Metal permeation was studied for the first time at single-cell resolution, showing high bioaccumulation in the epidermal layers and especially in mitotic cells, accumulating cobalt (Co) in the low fg range per cell. In this cellular phenotype, Co accumulation was correlated to DNA damage. While the amount of cobalt was significantly lower in the collagenous matrix of the dermal layer, cells in the vicinity of blood vessels and smooth muscle showed significant Co deposits as well. MeXpose provides unprecedented insights into metal bioaccumulation with the ability to explore novel relationships between metal exposure and cellular responses on a single-cell level, paving the way for advanced toxicological and therapeutic studies. ![Figure][1] Graphical abstract ### Competing Interest Statement The authors have declared no competing interest. [1]: pending:yes