Alejandro Brenes (@ajbrenes.com)

iPEX enables micrometre-resolution deep spatial proteomics via tissue expansion | Nature The number of spatial omics technologies being developed is increasing1. However, a missing tool is one that can locate proteins in tissues in an untargeted manner at high spatial resolution and coverage. Here we present in situ imaging proteomics via expansion (iPEX), which integrates isotropic tissue magnification2 with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging. iPEX provides scalable spatial resolution down to the micrometre scale and substantially increases the sensitivity of protein identification by 10–100-fold. Using the retina as a model, iPEX enabled the construction of spatial proteomic maps with high precision, the visualization of single-cell layers and extrasomatic structures and the identification of colocalized proteins. iPEX was readily applied to diverse tissues, including brain, intestine, liver and organoids, detecting 600–1,500 proteins at 1–5-µm effective pixel size. The application of iPEX to depict spatial proteomic maps in bra https://doi.org/10.1038/s41586-025-09734-0