[Background and Purpose] Application of human iPS cell-derived hepatocyte-like cells (HLCs) is expected to contribute to liver regenerative medicine and drug development. However, the use of these cells is restricted because HLCs prepared by the conventional differentiation induction method are immature compared with human adult hepatocytes. We aim to test the applicability of atelocollagen (AC) for HLC maturation. AC is a collagen whose antigenicity has been decreased by removal of telopeptides. Previously, we confirmed that the hepatic functions of the human liver cancer cell line HepG2 were enhanced when the cells were cultured on AC membrane (ACM), a processed form of AC in which the protein is embedded in biological membranes. In the present study, we report the effects of ACM on the functional maturation of iPS cell-derived HLCs.

[Methods] The formation of hepatoblast-like cells (HBCs) was induced by culturing human iPS cells (Tic) for 15 days on Matrigel^®-coated dishes in the presence of appropriate growth factors. The HBCs then were seeded in a low cell-binding 96-well plate at 25,000 cells/well to generate spheroids. The spheroids were transferred onto ACM (AteloCell^® CM24, Koken) and cultured up to Day 25. The resulting structures were evaluated in vitro for various liver functions.

[Results] HBC spheroids adhered to ACM, and HLCs were observed to migrate from the spheroids toward the outside of the structure. CYP3A4 activity and albumin secretion were elevated (2.3-fold and 5.5-fold, respectively) in HLCs that had been cultured on ACM (compared with conventional culture on Matrigel^®-coated plates). qRT-PCR showed that the expression of various hepatocyte-related genes was increased in HLCs cultured on ACM.

[Discussion] These results suggest that ACM will be of use for the functional maturation of HLCs. Further optimization of the induction conditions is expected to facilitate the use of these cells for regenerative medicine and drug development.