title: A preliminary study for constructing a bioartificial liver device with induced pluripotent stem cell-derived hepatocytes.
abstract: BACKGROUND
  Bioartificial liver systems, designed to support patients with liver failure, are composed of bioreactors and functional hepatocytes. Immunological rejection of the embedded hepatocytes by the host immune system is a serious concern that crucially degrades the performance of the device. Induced pluripotent stem (iPS) cells are considered a desirable source for bioartificial liver systems, because patient-derived iPS cells are free from immunological rejection. The purpose of this paper was to test the feasibility of a bioartificial liver system with iPS cell-derived hepatocyte-like cells.
  
  
  METHODS
  Mouse iPS cells were differentiated into hepatocyte-like cells by a multi-step differentiation protocol via embryoid bodies and definitive endoderm. Differentiation of iPS cells was evaluated by morphology, PCR assay, and functional assays. iPS cell-derived hepatocyte-like cells were cultured in a bioreactor module with a pore size of 0.2 μm for 7 days. The amount of albumin secreted into the circulating medium was analyzed by ELISA. Additionally, after a 7-day culture in a bioreactor module, cells were observed by a scanning electron microscope.
  
  
  RESULTS
  At the final stage of the differentiation program, iPS cells changed their morphology to a polygonal shape with two nucleoli and enriched cytoplasmic granules. Transmission electron microscope analysis revealed their polygonal shape, glycogen deposition in the cytoplasm, microvilli on their surfaces, and a duct-like arrangement. PCR analysis showed increased expression of albumin mRNA over the course of the differentiation program. Albumin and urea production was also observed. iPS-Heps culture in bioreactor modules showed the accumulation of albumin in the medium for up to 7 days. Scanning electron microscopy revealed the attachment of cell clusters to the hollow fibers of the module. These results indicated that iPS cells were differentiated into hepatocyte-like cells after culture for 7 days in a bioreactor module with a pore size of 0.2 μm.
  
  
  CONCLUSIONS
  We consider the combination of a bioreactor module with a 0.2-μm pore membrane and embedded hepatocytes differentiated from iPS cells to be a promising option for bioartificial liver systems. This paper provides the basic concept and preliminary data for an iPS cell-oriented bioartificial liver system.PACS code: 87. Biological and medical physics, 87.85.-d Biomedical engineering, 87.85.Lf Tissue engineering, 87.85.Tu Modeling biomedical systems.
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan. iwamuromasaya@yahoo.co.jp
authors.forename: Masaya
authors.initials: M
authors.lastname: Iwamuro
authors.forename: Hidenori
authors.initials: H
authors.lastname: Shiraha
authors.forename: Shuhei
authors.initials: S
authors.lastname: Nakaji
authors.forename: Masumi
authors.initials: M
authors.lastname: Furutani
authors.forename: Naoya
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Akinobu
authors.initials: A
authors.lastname: Takaki
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques / Q000295:instrumentation*; D002454:Cell Differentiation; D002460:Cell Line; D004867:Equipment Design; D019544:Equipment Failure Analysis; D022781:Hepatocytes / Q000166:cytology* / Q000502:physiology*; D019164:Liver, Artificial; D051379:Mice; D009924:Organ Culture Techniques / Q000295:instrumentation; D010865:Pilot Projects; D039904:Pluripotent Stem Cells / Q000166:cytology* / Q000502:physiology*; D054457:Tissue Scaffolds