Differentiation and selection of hepatocyte precursors in suspension spheroid culture of transgenic murine embryonic stem cells

Investigation of Clinical Safety of Human iPS Cell-Derived Liver Organoid Transplantation to Infantile Patients in Porcine Model

Transplantation of liver organoids has been investigated as a treatment alternative to liver transplantation for chronic liver disease. Transportal approach can be considered as a method of delivering organoids to the liver. It is important to set the allowable organoid amount and verify translocation by intraportal transplantation. We first examined the transplantation tolerance and translocation of porcine fetal liver-derived allogeneic organoids using piglets. Fetal liver-derived organoids generated from the Kusabira Orange-transduced pig were transplanted to the 10-day-old piglet liver through the left branch of the portal vein. All recipients survived without any observable adverse events. In contrast, both local and main portal pressures increased transiently during transplantation. In necropsy samples, Kusabira Orange-positive donor cells were detected primarily in the target lobe of the liver and partly in other areas, including the lungs and brain. As we confirmed the transplantation allowance by porcine fetal liver-derived organoids, we performed intraportal transplantation of human-induced pluripotent stem cell (iPSC)-derived liver organoid, which we plan to use in clinical trials, and portal pressure and translocation were investigated. Human iPSC-derived liver organoids were transplanted into the same 10-day-old piglet. Portal hypertension and translocation of human iPSC-derived liver organoids to the lungs were observed in one of two transplanted animals. Translocation occurred in the piglet in which patent ductus venosus (PDV) was observed. Therefore, a 28-day-old piglet capable of surgically ligating PDV was used, and after the PDV was ligated, human iPSC-derived liver organoids with the amount of which is scheduled in clinical trials were transplanted. This procedure inhibited the translocation of human iPSC-derived liver organoids to extrahepatic sites without no portal hypertension. In conclusion, human iPSC-derived liver organoids can be safely transplanted through the portal vein. Ligation of the ductus venosus prior to transplantation was effective in inhibiting extrahepatic translocation in newborns and infants.

HepaRG Self-Assembled Spheroids in Alginate Beads Meet the Clinical Needs for Bioartificial Liver

In liver tissue engineering, cell culture in spheroids is now well recognized to promote the maintenance of hepatic functions. However, the process leading to spheroids formation is time consuming, costly, and not easy to scale-up for further use in human bioartificial liver (BAL) applications. In this study, we encapsulated HepaRG cells (precursors of hepatocyte-like cells) in 1.5% alginate beads without preforming spheroids. Starting from a given hepatic biomass, we analyzed cell differentiation and metabolic performance for further use in a fluidized-bed BAL. We observed that cells self-rearranged as aggregates within the beads and adequately differentiated over time, in the absence of any differentiating factors classically used. On day 14 postencapsulation, cells displayed a wide range of hepatic features necessary for the treatment of a patient in acute liver failure. These activities include albumin synthesis, ammonia and lactate detoxification, and the efficacy of the enzymes involved in the xenobiotic metabolism (such as CYP1A1/2). Impact statement It has been recognized that culturing cells in spheroids (SPHs) is advantageous as they better reproduce the three-dimensional physiological microenvironment. This approach can be exploited in bioartificial liver applications, where obtaining a functional hepatic biomass is the major challenge. Our study describes an original method for culturing hepatic cells in alginate beads that makes possible the autonomous formation of SPHs after 3 days of culture. In turn, the cells differentiate adequately and display a wide range of hepatic features. They are also capable of treating a pathological plasma model. Finally, this setup can easily be scaled-up to treat acute liver failure.

The Regenerative Effect of Portal Vein Injection of Liver Organoids by Retrorsine/Partial Hepatectomy in Rats

In this study, we reveal that liver organoid transplantation through the portal vein is a safe and effective method for the treatment of chronic liver damage. The liver organoids significantly reconstituted the hepatocytes; hence, the liver was significantly enlarged in this group, compared to the monolayer cell transplantation group in the retrorsine/partial hepatectomy (RS/PH) model. In the liver organoid transplantation group, the bile ducts were located in the donor area and connected to the recipient bile ducts. Thus, the rate of bile reconstruction in the liver was significantly higher compared to that in the monolayer group. By transplanting liver organoids, we saw a level of 70% replacement of the damaged liver. Consequently, in the transplantation group, diminished ductular reaction and a decrease of placental glutathione S-transferase (GST-p) precancerous lesions were observed. After trans-portal injection, the human induced pluripotent stem cell (hiPSC)-derived liver organoids revealed no translocation outside the liver; in contrast, the monolayer cells had spread to the lungs. The hiPSC-derived liver organoids were attached to the liver in the immunodeficient RS/PH rats. This study clearly demonstrates that liver organoid transplantation through the portal vein is a safe and effective method for the treatment of chronic liver damage in rats.

Size-dependent hepatic differentiation of human induced pluripotent stem cells spheroid in suspension culture

Suspension culture of three-dimensional (3D) spheroid of human induced pluripotent stem cells (hiPSCs) has been known as a potential method to enhance the scalability of hepatic differentiation of hiPSCs. However, the impact of size-related factor of initial formed spheroid were not largely considered. To address this problem, we evaluate the impact of different specific spheroid size of hiPSCs by forming the individual spheroid from different number of hiPSCs and differentiated into hiPSCs-derived hepatocytes (iHeps). The results showed that larger spheroid exhibit enhanced capability to differentiated into hepatic lineage by increasing the expression marker albumin, CYP3A4 and lower expression of fetal hepatic marker AFP. Several factor such as the tendency of cystic like structure forming, the necrotic area of the large dense spheroid, and interference of WNT/β-catenin signaling was significantly affecting the resulted iHeps. In this study, we suggest that the optimal spheroid size for hepatic differentiation can be attained from 500 to 600 μm diameter spheroid formed from 12,500–25,000 hiPSCs. This size can be potentially applied for various practical use of hepatic differentiation in scalable suspension culture.

Long Term Liver Engraftment of Functional Hepatocytes Obtained from Germline Cell-Derived Pluripotent Stem Cells

One of the major hurdles in liver gene and cell therapy is availability of ex vivo-expanded hepatocytes. Pluripotent stem cells are an attractive alternative. Here, we show that hepatocyte precursors can be isolated from male germline cell-derived pluripotent stem cells (GPSCs) using the hepatoblast marker, Liv2, and induced to differentiate into hepatocytes in vitro. These cells expressed hepatic-specific genes and were functional as demonstrated by their ability to secrete albumin and produce urea. When transplanted in the liver parenchyma of partially hepatectomised mice, Liv2-sorted cells showed regional and heterogeneous engraftment in the injected lobe. Moreover, approximately 50% of Y chromosome-positive, GPSC-derived cells were found in the female livers, in the region of engraftment, even one month after cell injection. This is the first study showing that Liv2-sorted GPSCs-derived hepatocytes can undergo long lasting engraftment in the mouse liver. Thus, GPSCs might offer promise for regenerative medicine.

A Convenient and Efficient Method to Enrich and Maintain Highly Proliferative Human Fetal Liver Stem Cells

Pluripotent human hepatic stem cells have broad research and clinical applications, which are, however, restricted by both limited resources and technical difficulties with respect to isolation of stem cells from the adult or fetal liver. In this study, we developed a convenient and efficient method involving a two-step in situ collagenase perfusion, gravity sedimentation, and Percoll density gradient centrifugation to enrich and maintain highly proliferative human fetal liver stem cells (hFLSCs). Using this method, the isolated hFLSCs entered into the exponential growth phase within 10 days and maintained sufficient proliferative activity to permit subculture for at least 20 passages without differentiation. Immunocytochemistry, immunofluorescence, and flow cytometry results showed that these cells expressed stem cell markers, such as c-kit, CD44, epithelial cell adhesion molecule (EpCAM), oval cell marker-6 (OV-6), epithelial marker cytokeratin 18 (CK18), biliary ductal marker CK19, and alpha-fetoprotein (AFP). Gene expression analysis showed that these cells had stable mRNA expression of c-Kit, EpCAM, neural cell adhesion molecule (NCAM), CK19, CK18, AFP, and claudin 3 (CLDN-3) throughout each passage while maintaining low levels of ALB, but with complete absence of cytochrome P450 3A4 (C3A4), phosphoenolpyruvate carboxykinase (PEPCK), telomeric repeat binding factor (TRF), and connexin 26 (CX26) expression. When grown in appropriate medium, these isolated liver stem cells could differentiate into hepatocytes, cholangiocytes, osteoblasts, adipocytes, or endothelial cells. Thus, we have demonstrated a more economical and efficient method to isolate hFLSCs than magnetic-activated cell sorting (MACS). This novel approach may provide an excellent tool to isolate highly proliferative hFLSCs for tissue engineering and regenerative therapies.

The effectiveness of an anti-human IL-6 receptor monoclonal antibody combined with chemotherapy to target colon cancer stem-like cells

Recent studies have demonstrated that cancer stem cells (CSCs) can initiate and sustain tumor growth and exhibit resistance to clinical cytotoxic therapies. Therefore, CSCs represent the main target of anticancer therapy. Interleukin-6 (IL-6) promotes cellular proliferation and drug resistance in colorectal cancer, and its serum levels correlate with patient survival. Therefore, IL-6 and its downstream signaling molecule the signal transducer and activator of transcription-3 (STAT3) represent potential molecular targets. In the present study, we investigated the effects of IL-6 and its downstream signaling components on stem cell biology, particularly the chemoresistance of CSCs, to explore potential molecular targets for cancer therapy. The colon cancer cell line WiDr was cultured in serum-free, non-adherent, and three-dimensional spheroid-forming conditions to enrich the stem cell-like population. Spheroid-forming cells slowly proliferated and expressed high levels of Oct-4, Klf4, Bmi-1, Lgr5, IL-6, and Notch 3 compared with adherent cells. Treatment with an anti-human IL-6 receptor monoclonal antibody reduced spheroid formation, stem cell-related gene expression, and 5-fluorouracil (5-FU) resistance. In addition, IL-6 treatment enhanced the levels of p-STAT3 (Tyr705), the expression of Oct-4, Klf4, Lgr5, and Notch 3, and chemoresistance to 5-FU. siRNA targeting Notch 3 suppressed spheroid formation, Oct-4 and Lgr5 expression, and 5-FU chemoresistance, whereas STAT3 inhibition enhanced Oct-4, Klf4, Lgr5, and Notch 3 expression and 5-FU chemoresistance along with reduced spheroid growth. Taken together, these results indicate that IL-6 functions in dichotomous pathways involving Notch 3 induction and STAT3 activation. The former pathway is involved in cancer stem-like cell biology and enhanced chemoresistance, and the latter pathway leads to accelerated proliferation and reduced chemoresistance. Thus, an anti-human IL-6 receptor monoclonal antibody or Notch 3 inhibition may be superior to STAT3 inhibition for CSC-targeting therapies concomitant with anticancer drugs.

Molecular mechanisms underlying the enhanced functions of three-dimensional hepatocyte aggregates

Three-dimensional (3D) culture of hepatocytes leads to improved and prolonged synthetic and metabolic functions, but the underlying molecular mechanisms are unknown. In order to investigate the role of 3D cell-cell interactions in maintaining hepatocyte differentiated functions ex vivo, primary mouse hepatocytes were cultured either as monolayers on tissue culture dishes (TCD) or as 3D aggregates in rotating wall vessel (RWV) bioreactors. Global gene expression analyses revealed that genes upregulated in 3D culture were distinct from those upregulated during liver development and liver regeneration. Instead, they represented a diverse array of hepatocyte-specific functional genes with significant over-representation of hepatocyte nuclear factor 4α (Hnf4a) binding sites in their promoters. Expression of Hnf4a and many of its downstream target genes were significantly increased in RWV cultures as compared to TCD. Conversely, there was concomitant suppression of mesenchymal and cytoskeletal genes in RWV cultures that were induced in TCDs. These findings illustrate the importance of 3D cell-cell interactions in maintaining fundamental molecular pathways of hepatocyte function and serve as a basis for rational design of biomaterials that aim to optimize hepatocyte functions ex vivo for biomedical applications.

Generation of functional hepatocyte-like cells from human pluripotent stem cells in a scalable suspension culture

Recent advances in human embryonic and induced pluripotent stem cell-based therapies in animal models of hepatic failure have led to an increased appreciation of the need to translate the proof-of-principle concepts into more practical and feasible protocols for scale up and manufacturing of functional hepatocytes. In this study, we describe a scalable stirred-suspension bioreactor culture of functional hepatocyte-like cells (HLCs) from the human pluripotent stem cells (hPSCs). To promote the initial differentiation of hPSCs in a carrier-free suspension stirred bioreactor into definitive endoderm, we used rapamycin for "priming" phase and activin A for induction. The cells were further differentiated into HLCs in the same system. HLCs were characterized and then purified based on their physiological function, the uptake of DiI-acetylated low-density lipoprotein (LDL) by flow cytometry without genetic manipulation or antibody labeling. The sorted cells were transplanted into the spleens of mice with acute liver injury from carbon tetrachloride. The differentiated HLCs had multiple features of primary hepatocytes, for example, the expression patterns of liver-specific marker genes, albumin secretion, urea production, collagen synthesis, indocyanin green and LDL uptake, glycogen storage, and inducible cytochrome P450 activity. They increased the survival rate, engrafted successfully into the liver, and continued to present hepatic function (i.e., albumin secretion after implantation). This amenable scaling up and outlined enrichment strategy provides a new platform for generating functional HLCs. This integrated approach may facilitate biomedical applications of the hPSC-derived hepatocytes.