MALDI Mass Spectrometry Imaging for Evaluation of Therapeutics in Colorectal Tumor Organoids

Abstract

Patient-derived colorectal tumor organoids (CTOs) closely recapitulate the complex morphological, phenotypic, and genetic features observed in in vivo tumors. Therefore, evaluation of drug distribution and metabolism in this model system can provide valuable information to predict the clinical outcome of a therapeutic response in individual patients. In this report, we applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to examine the spatial distribution of the drug irinotecan and its metabolites in CTOs from two patients. Irinotecan is a prodrug and is often prescribed as part of therapeutic regimes for patients with advanced colorectal cancer. Irinotecan shows a time-dependent and concentration-dependent permeability and metabolism in the CTOs. More interestingly, the active metabolite SN-38 does not co-localize well with the parent drug irinotecan and the inactive metabolite SN-38G. The phenotypic effect of irinotecan metabolism was also confirmed by a viability study showing significantly reduced proliferation in the drug treated CTOs. MALDI-MSI can be used to investigate various pharmaceutical compounds in CTOs derived from different patients. By analyzing multiple CTOs from a patient, this method could be used to predict patient-specific drug responses and help to improve personalized dosing regimens. Graphical Abstract ᅟ.

Sample preparation strategies for high‐throughput mass spectrometry imaging of primary tumor organoids

“…Additionally, because of the grid architecture of the microarray, finding organoids can be done by eye. In previous MSI studies of organoids, organoid serial sections underwent hematoxylin and eosin staining to locate the organoids in sectioned samples . The main advantage of this microarray method is the increase in organoid sampling, which is a result of aligning more organoids on the same z‐axis for sectioning, as shown in Figure .…”

“…They also closely recapitulate in vivo‐like tissue architecture containing the genetic mutation drivers and morphological features of the cancer cells in the original tumor . Organoids have been made from a variety of tumor types including colorectal, pancreas, bladder, prostate, and breast cancers . Large numbers of organoid samples can be produced from a single patient, so large patient organoid biobanks can be generated that also contain correlated patient data and chemotherapy response .…”

“…MSI is a powerful technology that can image hundreds to thousands of molecules in a single experiment label free, as each molecule is tentatively identified based on its mass to charge ratio ( m/z value) with confirmation of molecular structure typically provided with tandem MS . MSI is an important analytical technique in drug discovery because it can image drug penetration and biomolecule distribution in organoids . Here, we apply MALDI MSI to organoids and describe sample preparation strategies to improve throughput of MS analysis of organoid systems.…”

Mass spectrometry imaging of endogenous metabolites in response to doxorubicin in a novel 3D osteosarcoma cell culture model

“…MALDI‐MSI‐based metabolite distribution in pellet cultures of chondrocytes shows varying spatial distributions in hypoxic vs normoxic regions, further supported by pellet cultures generated in hypoxic conditions . MALDI‐MSI has also successfully demonstrated spatial and temporal drug distribution (irinotecan, leucovorin, and its metabolites) in 3D MCTS cultures and irinotecan distributions in patient‐derived organoids . Although patient‐derived “organoid” models better represent patient tumours than cell line models and are in development for sarcoma, these are only well developed for epithelial cancers.…”

Intestinal Organoids: A Tool for Modelling Diet–Microbiome–Host Interactions

“…To overcome these limitations, mass spectrometry imaging (MSI) has emerged as a novel potent tool to assess the heterogeneity of a tissue at a single cell resolution [92][93][94][95]. Thus, by determining the spatial distribution and abundance of known or unknown molecular species, MSI can identify the cellular distribution of specific GMMs in the IO epithelium, the biotransformation of such compounds in metabolites, and the metabolic and/or proteomic response of intestinal cells to the compound [96].…”