Distribution of vitamin A‐storing lipid droplets in hepatic stellate cells in liver lobules—A comparative study

Abstract

To investigate the storage mechanisms of vitamin A, we examined the liver of adult polar bears and arctic foxes, which physiologically store a large amount of vitamin A, by high-performance liquid chromatography (HPLC), transmission electron microscopy (TEM) morphometry, gold chloride staining, fluorescence microscopy for the detection of autofluorescence of vitamin A, staining with hematoxylin-eosin (H&E), Masson's trichrome, and Ishii and Ishii's silver impregnation. HPLC revealed that the polar bears and arctic foxes contained 1.8 -1.9 ϫ 10 4 nmol total retinol (retinol plus retinyl esters) per gram liver. In the arctic foxes, the composition of the retinyl esters was found to be 51.1% palmitate, 26.6% oleate, 15.4% stearate, and 7% linoleate. The hepatic stellate cells of the arctic animals were demonstrated by TEM to contain the bulk of the vitamin A-lipid droplets in their cytoplasm. The liver lobules of the arctic animals showed a zonal gradient in the storage of vitamin A. The gradient was expressed as a symmetric crescendo-decrescendo profile starting at the periportal zone, peaking at the middle zone, and sloping down toward the central zone in the liver lobule. The density (i.e., cell number per area) of hepatic stellate cells was essentially the same among the zones. The gradient and the composition of the retinyl esters in storing vitamin A were not changed by differences in the vitamin A amount in the livers. These results indicate that the heterogeneity of vitamin A-storage capacity in hepatic stellate cells of arctic foxes and polar bears is genetically determined. Anat Rec Part A 271A: 240 -248, 2003.

Vitamin A storage in hepatic stellate cells in the regenerating rat liver: With special reference to zonal heterogeneity

“…It was previously reported that the liver lobule physiologically shows zonal heterogeneity in terms of vitamin A storage (Wake and Sato, 1993;Zou et al, 1998;Higashi and Senoo, 2003). In our present study, this heterogeneity of vitamin A storage disappeared during liver regeneration and did not return to normal by 14 days after PHx, at which time the liver volume generally does return to normal (Michalopoulos and DeFrances, 1997).…”

“…These cells also play a pivotal role in the regulation of vitamin A homeostasis (Senoo and Wake, 1985;Blomhoff et al, 1990;Senoo et al, 1990Senoo et al, , 1993aSenoo et al, , 1993bBlomhoff and Wake, 1991;Imai et al, 2000b). Earlier we reported the existence of a gradient of vitamin A-storing capacity in the liver and found that it was not dependent on the vitamin A amount in the organ (Higashi and Senoo, 2003). This gradient was expressed as a symmetrical biphasic distribution starting at the periportal zone, peaking at the middle zone, and sloping down toward the central zone in the liver lobule.…”

A dual reporter gene transgenic mouse demonstrates heterogeneity in hepatic fibrogenic cell populations

“…HSCs are heterogenous with regard to the vitamin A content. [27][28][29][30][31] However, the functional significance of this heterogeneity is unclear. It is possible that our isolation procedure to prepare HSC could result in the selection of cells with higher vitamin A content.…”

Hepatic Stellate Cells: Unique Characteristics in Cell Biology and Phenotype

“…All HSCs in hepatic parenchyma have a similar function but are heterogeneous in desmin expression, vitamin A storage, proliferative activity, cytokine production, and ECM production (Blomhoff and Wake, 1991;Greenwel et al, 1993;Zou et al, 1998;Higashi and Senoo, 2003). The activated HSCs in culture show myofibroblast-like cell shapes with well-developed stress fibers of actin cytoskeleton.…”