Expression of CD44 in rat hepatic progenitor cells

Area of Science:

• Hepatology
• Stem Cell Biology
• Molecular Biology

Background:

• Small hepatocytes (SHs) are hepatic progenitor cells.
• Phenotypical differences between SHs and mature hepatocytes (MHs) remain largely undefined.
• Understanding SH characteristics is crucial for regenerative medicine and liver disease research.

Purpose of the Study:

• To identify distinct molecular markers differentiating SHs from MHs.
• To investigate the expression patterns of CD44 standard form (CD44s) and CD44 variant form 6 (CD44v6) in SHs.
• To validate CD44 as a specific marker for SHs in both in vitro and in vivo models.

Main Methods:

• Gene expression profiling using DNA microarray analysis.
• Reverse transcription polymerase chain reaction (RT-PCR) to confirm gene expression.
• Immunocytochemistry for CD44s and CD44v6 in cultured SHs and d-galactosamine (GalN)-injured rat liver.
• Cell sorting of CD44s+ cells from GalN-treated livers for further analysis.

Main Results:

• DNA microarray and RT-PCR revealed restricted expression of CD44s and CD44v6 in SHs.
• CD44s expression was detected early in SH culture, preceding CD44v6 expression.
• CD44+ hepatocytes appeared in periportal areas post-GalN injury and decreased over time.
• Sorted CD44s+ cells demonstrated colony-forming ability and expressed hepatic markers.

Conclusions:

• CD44 serves as a specific marker for small hepatocytes (SHs).
• CD44 mRNA and protein expression are uniquely found in SHs.
• CD44 expression is upregulated during SH proliferation, both in vitro and in vivo.