Determination of platinum in human subcellular microsamples by inductively coupled plasma mass spectrometry

Trace element landscape of resting and activated human neutrophils on the sub-micrometer level

Every infection is a battle for trace elements. Neutrophils migrate first to the infection site and accumulate quickly to high numbers. They fight pathogens by phagocytosis and intracellular toxication. Additionally, neutrophils form neutrophil extracellular traps (NETs) to inhibit extracellular microbes. Yet, neutrophil trace element characteristics are largely unexplored. We investigated unstimulated and phorbol myristate acetate-stimulated neutrophils using synchrotron radiation X-ray fluorescence (SR-XRF) on the sub-micron spatial resolution level. PMA activates pinocytosis, cytoskeletal rearrangements and the release of NETs, all mechanisms deployed by neutrophils to combat infection. By analyzing Zn, Fe, Cu, Mn, P, S, and Ca, not only the nucleus but also vesicular granules were identifiable in the elemental maps. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) revealed a neutrophil-specific composition of Zn, Fe, Cu, and Mn in comparison with J774 and HeLa cells, indicating a neutrophil-specific metallome complying with their designated functions. When investigating PMA-activated neutrophils, the SR-XRF analysis depicted typical subcellular morphological changes: the transformation of nucleus and granules and the emergence of void vacuoles. Mature NETs were evenly composed of Fe, P, S, and Ca with occasional hot spots containing Zn, Fe, and Ca. An ICP-MS-based quantification of NET supernatants revealed a NETosis-induced decrease of soluble Zn, whereas Fe, Cu, and Mn concentrations were only slightly affected. In summary, we present a combination of SR-XRF and ICP-MS as a powerful tool to analyze trace elements in human neutrophils. The approach will be applicable and valuable to numerous aspects of nutritional immunity.

Assessing the intracellular concentration of platinum in medulloblastoma cell lines after Cisplatin incubation

Two different analytical approaches, external calibration and isotope dilution analysis both using flow-injection inductively coupled plasma mass spectrometry, have been developed and applied to determine the intracellular platinum concentration after Cisplatin incubation of two different medulloblastoma cell lines (UW228 and DAOY). As the internal or isotopically enriched standard was already used for cell lysis, maximum accuracy of the results was obtained, whereas a new home-built and inert injection system dramatically lowered carry-over effects and analyte loss. With limits of the detection well below 0.4μgL(-1) and typical relative standard deviations of 2%, a strong correlation between the cell viability in MTT assays and the incorporated amount of Pt could be shown, which was subsequently normalized to the protein content of the samples. DAOY cells did significantly ingest more Pt and showed a higher mortality, which supports the fact that transporter expression needs to be taken into account in order to obtain meaningful results.

Cellular uptake and subcellular distribution of ruthenium-based metallodrugs under clinical investigation versus cisplatin

The cellular uptake and subcellular distribution including adduct formation with genomic DNA and uptake into mitochondria of two ruthenium(iii)-based drugs in clinical trials, KP1019 and NAMI-A, and cisplatin, was investigated in cisplatin sensitive and resistant A2780 human ovarian carcinoma cells. These data indicate that reduced metal uptake into mitochondria in combination with increased binding towards low molecular weight components involved in detoxification mechanisms is essential for cisplatin resistance. The ruthenium drugs show distinct differences with respect to cisplatin, especially in the cisplatin resistant cells; in comparison to the sensitive cells, KP1019 exhibits higher cytotoxicity and an only slightly changed metabolism of the drug, whereas NAMI-A treatment results in increased intracellular ruthenium levels and a higher number of ruthenium-DNA adducts. In addition, size exclusion-inductively coupled mass spectrometry indicates that adduct formation with high molecular weight components in the particulate and nuclear fractions is crucial for the therapeutic effect of KP1019 in both cisplatin resistant and sensitive cell lines.

The application of inductively coupled plasma mass spectrometry in clinical pharmacological oncology research

Metal-based anticancer agents are frequently used in the treatment of a wide variety of cancer types. The monitoring of these anticancer agents in biological samples is important to understand their pharmacokinetics, pharmacodynamics, and metabolism. In addition, determination of metals originating from anticancer agents is relevant to assess occupational exposure of health care personnel working with these drugs. The high sensitivity of inductively coupled plasma mass spectrometry (ICP-MS) has resulted in an increased popularity of this technique for the analysis of metal-based anticancer drugs. In addition to the quantitative analysis of the metal of interest in a sample, ICP-MS can be used as an ultrasensitive metal selective detector in combination with speciation techniques such as liquid chromatography. In the current review we provide a systematic survey of publications describing the analysis of platinum- and ruthenium-containing anticancer agents using ICP-MS, focused on the determination of total metal concentrations and on the speciation of metal compounds in biological fluids, DNA- and protein-adducts, and environmental samples. We conclude that ICP-MS is a powerful tool for the quantitative analysis of metal-based anticancer agents from multiple sample sources.