Mutsunori Fujiwara & Yoshihiro Mezaki 
Regulation of Vitamin A Homeostasis by the Stellate Cell (Vitamin A-Storing Cell) System 

Vitamin A-storing cells in the liver exist in the space between parenchymal cells and liver sinusoidal endothelial cells of the hepatic lobule, and store 50-80% of vitamin A in the whole body as retinyl palmitate in lipid droplets in the cytoplasm. In physiological conditions, these cells play pivotal roles in the regulation of vitamin A homeostasis. In pathological conditions such as hepatic fibrosis or liver cirrhosis, hepatic stellate cells lose vitamin A, and synthesize a large amount of extracellular matrix components including collagen, proteoglycan, glycosaminoglycan, and adhesive glycoproteins. Morphology of these cells also changes from the star-shaped stellate cells to that of fibroblasts or myofibroblasts. This book discusses and presents research on vitamin A-storing cells.