For example, EVs from human dental pulp MSCs with HIF-1α (a master regulator of hypoxia) overexpression and cytokine (IFN-γ, IL-1β and TNF-α) preconditioning were produced, and these EVs had higher potency to alleviate the fibrillar collagen proportion and colon length shortening in a mouse colitis model than native EVs (159). Here, TNF is linked to colitis.