Ito cell

Ito cells, also known as hepatic stellate cells, lipocytes, or fat-storing cells, are pericytes found in the perisinusoidal space (a small area between the sinusoids and hepatocytes) of the liver. The stellate cell is the major cell type involved in liver fibrosis, which is the formation of scar tissue in response to liver damage.

Ito cells can be selectively stained with gold chloride, but their distinguishing feature in routine histological preparations is the presence of multiple lipid droplets in their cytoplasm. Stanciu A, Cotutiu C, Amalinei C. (2002) "New data about ITO cells." Rev Med Chir Soc Med Nat Iasi. 107(2):235-9. PMID 12638266 ] Reelin expressed by Ito cells has been shown to be a reliable marker in discerning them from other myofibroblasts. [Kobold D, Grundmann A, Piscaglia F, Eisenbach C, Neubauer K, Steffgen J, Ramadori G, Knittel T. (2002) "Expression of reelin in hepatic stellate cells and during hepatic tissue repair: a novel marker for the differentiation of HSC from other liver myofibroblasts." J Hepatol. 36(5):607-13. PMID 11983443] The expression of reelin is increased after liver injury.

In normal liver, stellate cells are described as being in a "quiescent" state. Quiescent stellate cells represent 5-8% of the total number of liver cells. [Geerts A. (2001) "History, heterogeneity, developmental biology, and functions of quiescent hepatic stellate cells." Semin Liver Dis. 21(3):311-35. PMID 11586463 ] Each cell has several long protrusions that extend from the cell body and wrap around the sinusoids. The lipid droplets in the cell body store vitamin A. The function and role of quiescent hepatic stellate cells is unclear. Recent evidence suggests a role as a liver-resident antigen-presenting cell presenting lipid antigens to and stimulating proliferation of NKT cells. Kaufmann (2007) "Ito Cells are Liver-Resident Antigen-Presenting Cells for Activating T Cell Responses" Immunity 26, 117-129, January 2007 PMID 17239632 ]

When the liver is damaged, stellate cells can change into an "activated" state. The activated stellate cell is characterized by proliferation, contractility, and chemotaxis. The amount of stored vitamin A decreases progressively in liver injury. ] The activated stellate cell is also responsible for secreting collagen scar tissue, which can lead to cirrhosis.

Literature

* John P. Iredale (2001) "Hepatic Stellate Cell Behavior During Resolution of Liver Injury." Seminars in Liver Disease, 21(3):427-436 PMID 11586470 - [http://www.medscape.com/viewarticle/410857_print free fulltext article] from Medscape.

* Adrian Reuben (2002) " [http://www3.interscience.wiley.com/cgi-bin/abstract/106597576/ABSTRACT?CRETRY=1&SRETRY=0 Ito becomes a star.] " Hepatology. Volume 35, Issue 2 , Pages 503 - 504 [http://www3.interscience.wiley.com/cgi-bin/fulltext/106597576/PDFSTART free fulltext PDF]

References

ee also

* Stellate cell

External links

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