Comparative study between lactose-silk fibroin conjugates and extracellular matrices as a substrate for the culture of human induced pluripotent stem cell-derived hepatocytes.

BACKGROUND: Human induced pluripotent stem cell (hiPSC)-derived hepatocytes are an attractive alternative cell source to primary human hepatocytes for tissue regeneration. OBJECTIVES: This study presents an application of lactose-silk fibroin conjugates (Lac-CY-SF) bearing 𝛽-galactose residues as a substrate for culture of hiPSC-derived hepatocytes. A comparison of hiPSC-derived hepatocytes cultured on three different substrates; Lac-CY-SF conjugates, Matrigel and type I collagen was performed. METHODS: Cell morphology, viability, maturation and albumin secretory function were assessed by phase-contrast microscopy, tetrazolium-based colorimetric assay, immunofluorescence staining and enzyme-linked immunosorbent assay. RESULTS: Morphological characteristics of the cells cultured on the conjugates resembled those on Matrigel throughout the 6-day culture period. The number of viable cells cultured on the conjugates was comparable to that on Matrigel at day 2 and 6. The protein expression of mature hepatocyte markers, asialoglycoprotein receptor 1 and albumin, by the cells cultured on the conjugates resembled that by the cells cultured on collagen at day 2 and 6. Albumin secretory function per cell cultured on the conjugates was higher than that on collagen and comparable to that on Matrigel. CONCLUSIONS: These limited results suggest that Lac-CY-SF conjugates may be as useful as Matrigel and collagen for cultivation of hiPSC-derived hepatocytes.

Generation of safe and therapeutically effective human induced pluripotent stem cell-derived hepatocyte-like cells for regenerative medicine.

Hepatocyte-like cells (HLCs) differentiated from human induced pluripotent stem (iPS) cells are expected to be applied for regenerative medicine. In this study, we attempted to generate safe and therapeutically effective human iPS-HLCs for hepatocyte transplantation. First, human iPS-HLCs were generated from a human leukocyte antigen-homozygous donor on the assumption that the allogenic transplantation might be carried out. Highly efficient hepatocyte differentiation was performed under a feeder-free condition using human recombinant laminin 111, laminin 511, and type IV collagen. The percentage of asialoglycoprotein receptor 1-positive cells was greater than 80%, while the percentage of residual undifferentiated cells was approximately 0.003%. In addition, no teratoma formation was observed even at 16 weeks after human iPS-HLC transplantation. Furthermore, harmful genetic somatic single-nucleotide substitutions were not observed during the hepatocyte differentiation process. We also developed a cryopreservation protocol for hepatoblast-like cells without negatively affecting their hepatocyte differentiation potential by programming the freezing temperature. To evaluate the therapeutic potential of human iPS-HLCs, these cells (1 × 106 cells/mouse) were intrasplenically transplanted into acute liver injury mice treated with 3 mL/kg CCl4 only once and chronic liver injury mice treated with 0.6 mL/kg CCl4 twice weekly for 8 weeks. By human iPS-HLC transplantation, the survival rate of the acute liver injury mice was significantly increased and the liver fibrosis level of chronic liver injury mice was significantly decreased. Conclusion: We were able to generate safe and therapeutically effective human iPS-HLCs for hepatocyte transplantation. (Hepatology Communications 2017;1:1058-1069).