Fig. 1
Experimental outline. a In vitro experiments. Water-soluble metabolites of either 4T1 or 67NR cancer cells or T-cells were extracted using a dual-phase extraction method. The metabolic profiles of the different cell types were analyzed by CEST-MRI and afterwards, results were validated by quantitative 1H-NMR spectroscopy. b In vivo experiments. 106 4T1 or 67NR cancer cells were implanted into the mammary fat pad of BALB/c mice. Longitudinal CEST-MR imaging during tumor progression was conducted on either day three, six or nine after tumor implantation. On a separate set of animals, 4T1 or 67NR tumor-bearing mice were treated with immune checkpoint inhibitors (ICI), starting three days after tumor implantation, followed by CEST-MRI on either day 6 or day 9. After the MRI scans, mice were sacrificed and ex vivo analysis of tumors was performed, including quantitative 1H-NMR spectroscopy, quantitative MALDI-2-MSI and immunohistochemistry. Created using Biorender.com