Spatial in situ mapping of RNA-chromatin interactions in human vasculature Abstract A breakthrough of this project is to simultaneously improve the state-of-art spatial resolution, dynamic range of RNA quantification, and applicable dimensions of human tissue by one to several orders of magnitude. This breakthrough will deliver to users extremely high-resolution, high-density, high-fidelity and reproducible spatial mapping slides (HiFi slides) for spatial transcriptome analysis or spatial mapping of modified- or interacting- nucleic acids. We will leverage HiFi slides to provide spatial transcriptome and spatial RNA-chromatin interactome mapping tools in unprecedented resolution. This project will generate HiFi spatial transcriptome, HiFi spatial RNA-crhomatin interactome, and high-resolution protein spatial profiles of 96 proteins from mesenteric arteries of veins, and the microvasculature from pancreas, liver and brain. These datasets will form the initial human EC biomolecular map (HuEC-MAP). These data will offer unprecedented insights to the molecular nature of the tissue-specific morphologies and functions of the blood vessel endothelium, which are critical to the development and functions of the associated tissues.