title: Immunomodulation of activated hepatic stellate cells by mesenchymal stem cells.
abstract: Bone marrow-derived mesenchymal stem cells (MSCs) have been reported to prevent the development of liver fibrosis in a number of pre-clinical studies. Marked changes in liver histopathology and serological markers of liver function have been observed without a clear understanding of the therapeutic mechanism by which stem cells act. We sought to determine if MSCs could modulate the activity of resident liver cells, specifically hepatic stellate cells (SCs) by paracrine mechanisms using indirect cocultures. Indirect coculture of MSCs and activated SCs led to a significant decrease in collagen deposition and proliferation, while inducing apoptosis of activated SCs. The molecular mechanisms underlying the modulation of SC activity by MSCs were examined. IL-6 secretion from activated SCs induced IL-10 secretion from MSCs, suggesting a dynamic response of MSCs to the SCs in the microenvironment. Blockade of MSC-derived IL-10 and TNF-alpha abolished the inhibitory effects of MSCs on SC proliferation and collagen synthesis. In addition, release of HGF by MSCs was responsible for the marked induction of apoptosis in SCs as determined by antibody-neutralization studies. These findings demonstrate that MSCs can modulate the function of activated SCs via paracrine mechanisms provide a plausible explanation for the protective role of MSCs in liver inflammation and fibrosis, which may also be relevant to other models of tissue fibrosis.
authors.affiliation: Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School and the Shriners Hospitals for Children, 51 Blossom Street, Boston, MA 02114, USA.
authors.forename: Biju
authors.initials: B
authors.lastname: Parekkadan
authors.forename: Daan
authors.initials: D
authors.lastname: van Poll
authors.forename: Zaki
authors.initials: Z
authors.lastname: Megeed
authors.forename: Naoya
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Arno W
authors.initials: AW
authors.lastname: Tilles
authors.forename: François
authors.initials: F
authors.lastname: Berthiaume
authors.forename: Martin L
authors.initials: ML
authors.lastname: Yarmush
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000276:immunology*; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology*; D005260:Female; D022781:Hepatocytes / Q000276:immunology*; D006801:Humans; D007155:Immunologic Factors / Q000276:immunology*; D059630:Mesenchymal Stem Cells / Q000276:immunology*; D018448:Models, Immunological; D019899:Paracrine Communication / Q000276:immunology*; D051381:Rats; D011917:Rats, Inbred Lew
chemical_list: D016207:Cytokines; D007155:Immunologic Factors