Purified Rat Liver Fat-Storing Cells in Culture Divide and Contain Collagen

Abstract

Primary cultures and cell lines were established from suspensions of purified fat-storing cells isolated from the rat liver. When seeded at a suitable density, fat-storing cells in primary culture reached confluency in 3 to 4 days and could be transferred and established as cell lines for at least two passages. The typical morphological characteristics of fat-storing cells in vivo were retained in the cells during primary culture. Vitamin A fluorescence was still associated with lipid droplets of cells in culture up to and including the second passage. Investigation of the cytoskeletal structure by indirect immunofluorescence showed the presence of vimentin, actin and tubulin in the cells; no alpha-prekeratin was present. The presence of vimentin suggested a fibroblastic or possible myogenic origin for fat-storing cells. The presence of connective tissue components in fat-storing cells in culture was demonstrated by indirect immunofluorescence. Collagen Types I and IV and laminin were present intracellularly in small granules in fat-storing cells in primary culture and in the first passage. Cells in the fourth passage contained only collagen Type 1. Fibronectin was only aligned extracellularly along the cell membrane, which did not exclude an extracellular source. Rat liver fat-storing cells in culture show a high proliferating capacity. Cell multiplication during prolonged culture was associated with phenotypic transition to a more fibroblastic appearance and gradual disappearance of vitamin A. These results indicate that fat-storing cells may be among the cell types involved in pathological changes observed during development of liver fibrosis.

Targeting of αv integrin identifies a core molecular pathway that regulates fibrosis in several organs

“…In the liver, hepatic stellate cells (liver specific pericytes) are the major source of extracellular matrix during hepatic fibrogenesis 26,27 . To date, no effective strategy has been developed to reliably delete genes specifically in HSCs.…”

Deactivation of Hepatic Stellate Cells During Liver Fibrosis Resolution in Mice

“…We chose CreER expression to be driven by vimentin, an intermediate filament that is expressed in mesenchymal cell populations with very high expression in myofibroblasts. 19 In the liver, vimentin is predominantly expressed in HSCs but may also be found in vascular smooth muscle cells and portal fibroblasts 20,21 To generate a BAC transgenic mouse driven by the vimentin promoter, we inserted a CreER cassette in a BAC containing the mouse vimentin locus (Vim-CreER, Suppl.Fig.3). Using the mTommGFP Cre reporter mouse 22 in which mTom is expressed in the absence of Cre activity and mGFP in cells with Cre activity (Fig.2A), we analyzed VimCreER-marked cell populations in the liver and various other organs.…”

Pericytes at the intersection between tissue regeneration and pathology: Figure 1

“…In the liver, pericytes are also called Ito or hepatic stellate cells and reside in close contact with vascular endothelial cells [176,177]. Early studies indicating that they play a central role in hepatic fibrosis by producing collagen [178,179] were confirmed using collagen–GFP transgenic mice [180] and in a recent lineage-tracing study [181]. The authors generated pericyte-specific, lecithin-retinol acyltransferase (Lrat) Cre mice, which marked nearly all pericytes.…”