Fibronectin extra domain-A promotes hepatic stellate cell motility but not differentiation into myofibroblasts.
OBJECTIVE
Myofibroblasts are the primary cell type involved in physiologic wound healing and its pathologic counterpart, fibrosis. Cellular fibronectin that contains the alternatively spliced extra domain A (EIIIA) is up-regulated during these processes and is believed to promote myofibroblast differentiation. We sought to determine the requirement for EIIIA in fibrosis and differentiation of myofibroblasts in rodent livers.


METHODS
We used a mechanically tunable hydrogel cell culture system to study differentiation of primary hepatic stellate cells and portal fibroblasts from rats into myofibroblasts. Liver fibrosis was induced in mice by bile duct ligation or administration of thioacetamide.


RESULTS
EIIIA was not required for differentiation of rat hepatic stellate cells or portal fibroblasts into fibrogenic myofibroblasts. Instead, hepatic stellate cells cultured on EIIIA-containing cellular fibronectin formed increased numbers of lamellipodia; their random motility and chemotaxis also increased. These increases required the receptor for EIIIA, the integrin α(9)β(1). In contrast, the motility of portal fibroblasts did not increase on EIIIA, and these cells expressed little α(9)β(1). Male EIIIA(-/-) mice were modestly protected from thioacetamide-induced fibrosis, which requires motile hepatic stellate cells, but not from bile duct ligation-induced fibrosis, in which portal fibroblasts are more important. Notably, myofibroblasts developed during induction of fibrosis with either thioacetamide or bile duct ligation in EIIIA(-/-) mice.


CONCLUSIONS
EIIIA is dispensable for differentiation of hepatic stellate cells and portal fibroblasts to myofibroblasts, both in culture and in mouse models of fibrosis. Our findings, however, indicate a role for EIIIA in promoting stellate cell motility and parenchymal liver fibrosis.
Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
Abby L
AL
Olsen
Bridget K
BK
Sackey
Cezary
C
Marcinkiewicz
David
D
Boettiger
Rebecca G
RG
Wells
D000818:Animals; D001652:Bile Ducts / Q000601:surgery; D018929:Cell Culture Techniques; D002465:Cell Movement; D054338:Cell Transdifferentiation; D002478:Cells, Cultured; D005260:Female; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D005353:Fibronectins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D055166:Hepatic Stellate Cells / Q000378:metabolism* / Q000473:pathology; D020100:Hydrogels; D039001:Integrin alpha Chains / Q000378:metabolism; D019012:Integrin beta1 / Q000378:metabolism; D008026:Ligation; D008105:Liver Cirrhosis, Biliary / Q000209:etiology / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D008106:Liver Cirrhosis, Experimental / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D058628:Myofibroblasts / Q000378:metabolism* / Q000473:pathology; D020033:Protein Isoforms; D011554:Pseudopodia / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013853:Thioacetamide
D005353:Fibronectins; D020100:Hydrogels; D039001:Integrin alpha Chains; D019012:Integrin beta1; D020033:Protein Isoforms; C572454:extra domain A fibronectin, mouse; C084613:integrin alpha9; D013853:Thioacetamide