Hyaluronan gates fibroblast activation

This proposed theory asks whether fibrosis, tissue scarring that can disrupt a stem-cell niche, is controlled by hyaluronan size where immune cells meet fibroblasts, the cells that build connective tissue. Human niche explant co-cultures would compare interfaces while M2-polarized macrophages, immune cells in a defined state, release transforming growth factor beta-1 (TGF-beta1), a fibroblast-activating signal. One gets ultra-high-molecular-weight hyaluronan, over 6 MDa; the other low-molecular-weight material, under 500 kDa, at matched TGF-beta1. The hypothesis is that the large-molecule mesh sequesters latent TGF-beta1, its inactive precursor, and prevents mechanical activation. Immunofluorescence could detect lower alpha-smooth-muscle actin (alphaSMA), an activation marker, behind that mesh.