Functional Analysis of Induced Human Ballooned Hepatocytes in a Cell Sheet-Based Three Dimensional Model.

Area of Science:

• Hepatology
• Cell Biology
• Biochemistry

Background:

• Ballooned hepatocytes (BHs) are a key histological feature of nonalcoholic steatohepatitis (NASH).
• The functional consequences of BHs on liver-specific functions remain largely unknown.
• An experimental model of human induced-BHs (iBH) was previously established using cell sheet technology.

Purpose of the Study:

• To determine the functional impact of iBHs in a primary human hepatocyte/normal human dermal fibroblast co-culture system.
• To compare iBH function with normal hepatocytes in a co-culture model.
• To investigate potential therapeutic targets for NASH-related hepatic dysfunction.

Main Methods:

• Co-culture of primary human hepatocytes (PHH) with either normal human dermal fibroblasts (NHDF) or 3T3-J2 fibroblasts to create iBH and control cell sheets.
• Assessment of albumin secretion, urea synthesis, and cytochrome P450 (CYP) enzyme activities (CYP1A2, CYP3A4) in iBHs.
• Histological analysis for bile canaliculi integrity and measurement of TGF-β1 secretion.

Main Results:

• iBHs showed normal albumin secretion but significantly reduced urea synthesis and CYP activities (CYP1A2, CYP3A4).
• Loss of bile canaliculi was observed in iBHs, consistent with clinical NASH findings.
• PHH/NHDF cell sheets exhibited higher TGF-β1 secretion; TGF-β inhibition and obeticholic acid treatment improved iBH histology.

Conclusions:

• iBHs accurately recapitulate NASH histology and clinically relevant hepatic dysfunctions.
• TGF-β and bile acid signaling pathways are implicated in iBH formation.
• This model provides insights into NASH pathogenesis and potential therapeutic strategies.