Pharmacological induction of a progenitor state for the efficient expansion of primary human hepatocytes

The liver is an organ with strong regenerative capacity, yet primary hepatocytes have a low amplification potential in vitro, a major limitation for the cell-based therapy of liver disorders and for ex vivo biological screens. Induced pluripotent stem cells (iPSC) may help to circumvent this obstacle, but often harbor genetic and epigenetic abnormalities limiting their potential. Here, we describe the pharmacological induction of proliferative human hepatic progenitor cells (HPC) through a cocktail of growth factors and small molecules mimicking the signaling events involved in liver regeneration. Human HPC from healthy donors and pediatric patients proliferated vigorously while maintaining their genomic stability and could be re-differentiated in vitro into metabolically competent cells that supported the replication of hepatitis B and Delta viruses. Re-differentiation efficiency was boosted by 3D culture. Finally, transcriptome analysis showed that HPC were more closely related to mature hepatocytes than iPSC-derived hepatocyte-like cells were. Conclusion: HPC induction holds promises for a variety of applications such as ex vivo disease modeling, personalized drug testing or metabolic studies and development of a bio-artificial liver.