Thy-1 is expressed in hepatic myofibroblasts and not oval cells in stem cell-mediated liver regeneration

Am J Pathol. 2007 Nov;171(5):1529-37. doi: 10.2353/ajpath.2007.070273. Epub 2007 Sep 20.

Abstract

Thy-1, a marker of hematopoietic stem cells, has been reported to be expressed by oval cells proliferating during stem cell-mediated regeneration in rat liver, suggesting a relationship between the two cell populations. Consequently, Thy-1 has become an accepted cell surface marker to sort hepatic oval cells. In the present study we used the well-characterized 2-acetylaminfluorene/partial hepatectomy model to induce transit-amplification of hepatic oval cells in the regenerating liver and characterized Thy-1 expression using Northern hybridization, quantitative reverse transcriptase-polymerase chain reaction analysis, immunofluorescence confocal microscopy, and immunoelectronmicroscopy. We found that Thy-1 expression was induced during transit-amplification of the oval cell population, but Thy-1 mRNA was not present in the alpha-fetoprotein-expressing oval cells. Thy-1 protein was consistently present outside the basement membrane surrounding the oval cells. It overlapped frequently with smooth muscle actin staining. A similar cellular localization of the Thy-1 protein was found on human liver specimens with ductular reactions obtained from patients with fulminant liver failure. Furthermore, Thy-1 was expressed by myofibroblasts in experimental liver fibrosis models without oval cell proliferation. We conclude that Thy-1 is not a marker of oval cells but is present on a subpopulation of myofibroblasts/stellate cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation
  • Cell Proliferation
  • Fibroblasts / metabolism*
  • Fibroblasts / pathology
  • Hepatocytes / metabolism
  • Hepatocytes / pathology
  • Humans
  • Liver / metabolism
  • Liver / pathology
  • Liver / physiology*
  • Liver Cirrhosis, Experimental / metabolism
  • Liver Cirrhosis, Experimental / pathology
  • Liver Failure, Acute / metabolism
  • Liver Failure, Acute / pathology
  • Liver Regeneration*
  • Male
  • Rats
  • Rats, Inbred F344
  • Stem Cells / physiology*
  • Thy-1 Antigens / biosynthesis*

Substances

  • Thy-1 Antigens