O-SNAP: A comprehensive pipeline for spatial profiling of chromatin architecture

We present O-SNAP (Objective Single-Molecule Nuclear Architecture Profiler), a comprehensive pipeline for the automated extraction, comparison, and classification of nuclear features from single-molecule localization microscopy (SMLM) data. O-SNAP quantifies 144 interpretable, biologically grounded spatial features describing chromatin organization or histone mark distributions at nanoscale resolution. The pipeline includes modules for pairwise comparison of features using volcano plots, feature set enrichment analysis, robust feature selection and classification of cell states, and pseudotime trajectory inference. We validate O-SNAP across diverse biological contexts, including fibroblast-to-stem cell reprogramming, tendon disease, histone variant sensitivity to oxidative stress, and chondrocyte de-differentiation, demonstrating its ability to detect subtle changes in nanoscale chromatin organization across diverse biological transitions.