Stellate Cells

Stellate cells, formerly known as Ito cells, fat-storing cells, perisinusoidal cells or lipocytes, are the major storage sites for vitamin A.

Hepatic stellate cells (HSCs) are located in the space of Disse between the hepatic epithelial cells and sinusoidal endothelial cells, accounting for 5%-8% of the cells in the liver. In a healthy liver, stellate cells are quiescent and contain large amounts of vitamin A lipid droplets. When the liver is injured due to hepatic toxins or viral infection, HSCs receive signals secreted by damaged hepatocytes and immune cells to transdifferentiate into activated myofibroblast-like cells. As the primary extracellular matrix-producing cells in liver, activated stellate cells generate a temporary scar at the site of injury to protect the liver from further damage. In addition, HSCs also secrete cytokines and growth factors that promote the regeneration of hepatic epithelial cells. Because of their important roles in liver repair and disease pathogenesis, HSCs have been a hot spot in liver research.

The field of pancreatic stellate cell (PSC) biology is very young, as essential in vitro tools to study these cells (i.e., methods to isolate and culture PSCs) were not developed until 1998. PSCs constitute the pancreas stroma. The cells carry out various functions, including forming the extracellular matrix, stimulating amylase secretion, phagocytosis, and contributing to immunity. Quiescent PSCs are characterized by vitamin A droplets, once activated, they exhibit myofibroblast-like morphology and are responsible for the fibrogenesis observed in pancreatitis and pancreatic ductal adenocarcinoma. Furthermore, it has been shown that PSCs support tumor metabolism by inducing autophagic alanine secretion.