Itocellen

Itocellen, commonly referred to in English as Ito cells, are hepatic stellate cells located in the perisinusoidal space of Disse in the liver. They reside between hepatocytes and sinusoidal endothelial cells and are identified by their lipid-rich cytoplasm containing vitamin A stored in retinyl esters. In a healthy liver, Ito cells contribute to vitamin A storage and retinoid metabolism and participate in the regulation of extracellular matrix turnover and immune-related signaling.

Upon liver injury from factors such as alcohol, viral infection, or cholestasis, Ito cells undergo activation. They lose most of their lipid droplets, upregulate markers such as alpha-smooth muscle actin, proliferate, and adopt a myofibroblast-like phenotype. Activated Ito cells synthesize extracellular matrix components, particularly collagens type I and III, and contribute to fibrotic scar formation. They also influence matrix remodeling through mediators such as matrix metalloproteinases and their inhibitors and respond to profibrotic signals like transforming growth factor beta.

Because of their central role in hepatic fibrosis, Ito cells are a major focus of research into anti-fibrotic therapies and liver regeneration. They interact with other liver cell types, including Kupffer cells and liver sinusoidal endothelial cells, whose signals help regulate Ito cell activation. The term Ito cells honors Toshio Ito, who described their distinctive perisinusoidal location and retinoid storage in early histological studies of the liver.