Theory 04/Tissue neighbourhoods/Spatial transcriptomics
Cell Fate Depends on the Neighbourhood
A cell's identity is set by the ratio of signals from its immediate neighbours to signals from the tissue average, so two cells with identical genomes differ because of who is next to them.
01Mechanism
Paracrine signalling decays over a few cell diameters; local composition therefore dominates over bulk composition.
02Prediction
State should track local composition more than global.
03Refutation
State explained by global tissue type would remove the neighbourhood term.
04What makes it checkable
Spatial transcriptomics measures expression while preserving position, so neighbourhood composition and cell state are recorded together rather than inferred from dissociated tissue.
05Why it was not testable before
Dissociation destroyed the geography; the neighbourhood was unmeasurable until position could be retained.