In Situ Mass Spectrometry Imaging and Ex Vivo Characterization of Renal Crystalline Deposits Induced in Multiple Preclinical Drug Toxicology Studies

Abstract

Drug toxicity observed in animal studies during drug development accounts for the discontinuation of many drug candidates, with the kidney being a major site of tissue damage. Extensive investigations are often required to reveal the mechanisms underlying such toxicological events and in the case of crystalline deposits the chemical composition can be problematic to determine. In the present study, we have used mass spectrometry imaging combined with a set of advanced analytical techniques to characterize such crystalline deposits in situ. Two potential microsomal prostaglandin E synthase 1 inhibitors, with similar chemical structure, were administered to rats over a seven day period. This resulted in kidney damage with marked tubular degeneration/regeneration and crystal deposits within the tissue that was detected by histopathology. Results from direct tissue section analysis by matrix-assisted laser desorption ionization mass spectrometry imaging were combined with data obtained following manual crystal dissection analyzed by liquid chromatography mass spectrometry and nuclear magnetic resonance spectroscopy. The chemical composition of the crystal deposits was successfully identified as a common metabolite, bisulphonamide, of the two drug candidates. In addition, an un-targeted analysis revealed molecular changes in the kidney that were specifically associated with the area of the tissue defined as pathologically damaged. In the presented study, we show the usefulness of combining mass spectrometry imaging with an array of powerful analytical tools to solve complex toxicological problems occurring during drug development.

Mapping Antiretroviral Drugs in Tissue by IR-MALDESI MSI Coupled to the Q Exactive and Comparison with LC-MS/MS SRM Assay

“…While there obviously room for improvement, the low/high concentration ratios between LC-MS/MS and IR-MALDESI are in fairly good agreement. A correlation between MSI and LC-MS/MS has been demonstrated previously for other ionization methods including MALDI [18, 50, 60-70] and DESI,[22, 71-72] but this is the first example of agreement between IR-MALDESI MSI with LC-MS/MS. Given that LC-MS/MS is a validated quantitation method; the correlation between the average intensities from IR-MALDESI with the absolute quantities determined by LC-MS/MS provides a foundation for quantification directly from an imaging experiment.…”

“…In some cases the additional knowledge gained from endogenous distributions can provide valuable insight on the impact of the drug on the local environment, implications for site-specific efficacy and toxicity, and can be used to identify certain histological features. [11, 16-18] MSI is befitting to drug discovery and development where the early understanding of preclinical drug distribution (and without requiring a radiolabel) can improve efficiency by narrowing the list of potential candidates.…”

Quantification in MALDI-MS imaging: what can we learn from MALDI-selected reaction monitoring and what can we expect for imaging?

“…As an example, Nilsson et al demonstrated that compounds administered by inhaled delivery at standard pharmacological dosage can be quantitatively detected by MALDI-MSI, using both MS and MS/MS modes, with acceptable accuracies and precisions [13]. Another study correlated the MALDI-MSI response with quantitative LC-MS/MS performed on adjacent tissue sections and, after harvesting from rats, several single doses of olanzapine at different concentrations [14].…”

Label-free molecular imaging of the kidney

“…82,112–114 Nilsson et al . 112 utilized IMS to examine the accumulation of preclinical crystalline deposits within the kidney, which are common phenotypes of nephrotoxicity that are often difficult to identify.…”

“…82,112–114 Nilsson et al . 112 utilized IMS to examine the accumulation of preclinical crystalline deposits within the kidney, which are common phenotypes of nephrotoxicity that are often difficult to identify. The administration of 2 potential microsomal prostaglandin E synthase-1 (mPGES-1) inhibitors resulted in multiple signs of renal damage, including increased plasma urea, creatinine, and potassium levels; tubular degeneration/ regeneration; and crystal deposits in rat kidneys.…”