Isolation and characterization of portal branch ligation-stimulated Hmga2-positive bipotent hepatic progenitor cells

Syngeneic implantation of mouse hepatic progenitor cell-derived three-dimensional liver tissue with dense collagen fibrils

BACKGROUND

Liver transplantation is a therapy for irreversible liver failure; however, at present, donor organs are in short supply. Cell transplantation therapy for liver failure is still at the developmental stage and is critically limited by a shortage of human primary hepatocytes.

AIM

To investigate the possibility that hepatic progenitor cells (HPCs) prepared from the portal branch-ligated hepatic lobe may be used in regenerative medicine, we attempted to enable the implantation of extracellular matrices containing organoids consisting of HPC-derived hepatocytes and non-parenchymal cells.

METHODS

In vitro liver organoid tissue has been generated by accumulating collagen fibrils, fibroblasts, and HPCs on a mesh of polylactic acid fabric using a bioreactor; this was subsequently implanted into syngeneic wild-type mice.

RESULTS

The in vitro liver organoid tissues generated transplantable tissues in the condensed collagen fibril matrix and were obtained from the mouse through partial hepatectomy.

CONCLUSION

Liver organoid tissue was produced from expanded HPCs using an originally designed bioreactor system. This tissue was comparable to liver lobules, and with fibroblasts embedded in the network collagen fibrils of this artificial tissue, it is useful for reconstructing the hepatic interstitial structure.

Oncological transformation in vitro of hepatic progenitor cell lines isolated from adult mice

Colorectal cancer cells can transfer the oncogene KRAS to distant cells, predisposing them to malignant transformation (Genometastasis Theory). This process could contribute to liver metastasis; besides, hepatic progenitor cells (HPCs) have been found to be involved in liver malignant neoplasms. The objective of this study is to determine if mouse HPCs—Oval cells (OCs)—are susceptible to incorporate Kras GAT (G12D) mutation from mouse colorectal cancer cell line CT26.WT and if OCs with the incorporated mutation behave like malignant cells. To achieve this, three lines of OCs in different conditions were exposed to CT26.WT cells through transwell co-culture for a week. The presence of Kras^G12D and capacity to form tumors were analyzed in treated samples by droplet digital PCR and colony-forming assays, respectively. The results showed that the Kras^G12D mutation was detected in hepatic culture conditions of undifferentiated OCs and these cells were capable of forming tumors in vitro. Therefore, OCs are susceptible to malignant transformation by horizontal transfer of DNA with Kras^G12D mutation in an undifferentiated condition associated with the liver microenvironment. This study contributes to a new step in the understanding of the colorectal metastatic process.

Hepatocytes and Endothelial Networks in a Fluid-Based In Vitro Model of Liver Drug Metabolism

Drug-induced liver toxicity remains a major cause of drug withdrawal from animal testing and human clinical trials. A functional liver culture model corresponding to the liver is urgently required; however, in previous liver models, it has proven difficult to stably maintain multiple liver functions. Previously reported fluid-based systems have some advantages for hepatocyte culture, but have insufficient liver-specific functions because they simply involve moving conventional hepatocyte cultures from a dish into a fluid-based system. Importantly, these cultures have no liver tissue-specific structures that construct liver-specific cellular polarities, such as apical, basolateral, and basal faces. In this study, we developed a fluid-based system for our liver tissue culture models. The liver tissues that were constructed in our originally designed fluid-based systems represent a tissue culture model for studying hepatic functions. Together, our findings show that by mimicking the structure of the liver in the body, our system effectively maintains multiple liver-specific functions. Impact statement A functional liver culture model corresponding to the liver is urgently required; however, in previous liver models, it has proven difficult to stably maintain multiple liver functions. In this study, we developed a fluid-based system for our liver tissue culture models. The liver tissues that were constructed in our originally designed fluid-based systems represent a tissue culture model for studying hepatic functions. Together, our findings show that by mimicking the structure of the liver in the body, our system effectively maintains multiple liver-specific functions.

Treatment with specific soluble factors promotes the functional maturation of transcription factor-mediated, pancreatic transdifferentiated cells

Pancreatic lineage-specific transcription factors (TFs) display instructive roles in converting adult cells to endocrine pancreatic cells through a process known as transdifferentiation. However, little is known about potential factors capable of accelerating transdifferentiation following transduction to achieve the functional maturation of transdifferentiated cells. In this study, we demonstrated, using adult liver-derived progenitor cells, that soluble factors utilized in pancreatic differentiation protocols of pluripotent stem cells promote functional maturation of TFs-mediated transdifferentiated cells. Treatment with an N2 supplement in combination with three soluble factors (glucagon-like peptide-1 [GLP-1] receptor agonist, notch inhibitor, and transforming growth factor-β [TGF-β] inhibitor) enhanced liver-to-pancreas transdifferentiation based on the following findings: i) the incidence of c-peptide-positive cells increased by approximately 1.2-fold after the aforementioned treatment; ii) the c-peptide expression level in the treated cells increased by approximately 12-fold as compared with the level in the untreated cells; iii) the treated cells secreted insulin in a glucose-dependent manner, whereas the untreated cells did not; and iv) transplantation of treated-transdifferentiated cells into streptozotocin-induced immunodeficient diabetic mice led to the amelioration of hyperglycemia. These results suggest that treatment with specific soluble factors promotes the functional maturation of transdifferentiated cells. Our findings could facilitate the development of new modalities for cell-replacement therapy for patients with diabetes.

Development of hepatoma-derived, bidirectional oval-like cells as a model to study host interactions with hepatitis C virus during differentiation

Directed differentiation of human stem cells including induced pluripotent stem cells into hepatic cells potentially leads to acquired susceptibility to hepatitis C virus (HCV) infection. However, cellular determinants that change their expression during cell reprogramming or hepatic differentiation and are pivotal for supporting the HCV life cycle remain unclear. In this study, by introducing a set of reprogramming factors, we established HuH-7-derived oval-like cell lines, Hdo-17 and -23, which possess features of bipotential liver precursors. Upon induction of hepatocyte differentiation, expression of mature hepatocyte markers and hepatoblast markers in cells increased and decreased, respectively. In contrast, in response to cholangiocytic differentiation induction, gene expression of epithelium markers increased and cells formed round cysts with a central luminal space. Hdo cells lost their susceptibility to HCV infection and viral RNA replication. Hepatic differentiation of Hdo cells potentially led to recovery of permissiveness to HCV RNA replication. Gene expression profiling showed that most host-cell factors known to be involved in the HCV life cycle, except CD81, are expressed in Hdo cells comparable to HuH-7 cells. HCV pseudoparticle infectivity was significantly but partially recovered by ectopic expression of CD81, suggesting possible involvement of additional unidentified factors in HCV entry. In addition, we identified miR200a-3p, which is highly expressed in Hdo cells and stem cells but poorly expressed in differentiated cells and mature hepatocytes, as a novel negative regulator of HCV replication. In conclusion, our results showed that epigenetic reprogramming of human hepatoma cells potentially changes their permissivity to HCV.

High mobility group AT-hook 2 is overexpressed in hepatoblastoma

Hepatoblastoma is the most frequent malignant hepatic tumor in children. Expression of high mobility group AT-hook 2, an architectural nuclear factor and marker for hepatic progenitor cells, has not been studied in detail in hepatocellular neoplasms. Immunohistochemical stains using antibodies against high mobility group AT-hook 2, β-catenin, glypican-3, p53, and Ki-67 were performed in 15 hepatoblastomas, 15 fibrolamellar hepatocellular carcinomas, 34 hepatocellular carcinomas (12, ≤30 years old; 22, >30 years old), and 22 hepatic adenomas. High mobility group AT-hook 2 was expressed in all 15 hepatoblastomas, including all fetal and embryonal components, significantly higher than in 41.7% (5/12) of hepatocellular carcinomas of 30 years or younger (P = .001) and in 9% (2/22) of hepatocellular carcinomas of older than 30 years (P < .001). Aberrant β-catenin expression was detected in 80% (12/15) of hepatoblastomas, 41.6% (5/12) of hepatocellular carcinomas of 30 years or younger, and 18.2% (4/22) of hepatocellular carcinomas of older than 30 years. All 15 fibrolamellar hepatocellular carcinomas and 22 hepatic adenomas were negative for high mobility group AT-hook 2 or β-catenin. High mobility group AT-hook 2 and β-catenin expression correlated positively (P = .017; τ = 0.522) in 34 hepatocellular carcinomas. β-Catenin and glypican-3 exhibited a distinct spatial distribution within hepatoblastomas; glypican-3 was more frequently expressed in fetal components (P = .007), whereas β-catenin tended to be more frequently expressed in embryonal components (P = .062). In conclusion, high mobility group AT-hook 2 is expressed in all hepatoblastomas and could be used as a sensitive marker in their diagnosis. High mobility group AT-hook 2 was also expressed in a subset of hepatocellular carcinomas in association with β-catenin expression; this might represent a subtype of hepatocellular carcinoma with hepatic progenitor cell differentiation.

Stem cell differentiation and human liver disease

Human stem cells are scalable cell populations capable of cellular differentiation. This makes them a very attractive in vitro cellular resource and in theory provides unlimited amounts of primary cells. Such an approach has the potential to improve our understanding of human biology and treating disease. In the future it may be possible to deploy novel stem cell-based approaches to treat human liver diseases. In recent years, efficient hepatic differentiation from human stem cells has been achieved by several research groups including our own. In this review we provide an overview of the field and discuss the future potential and limitations of stem cell technology.

Hemodynamic measurements in a sheep model with a hollow fiber artificial kidney containing modified cellulose

HFAK-RC caused pronounced leukopenia, increase in TXB2 levels in plasma and hemodynamic pressure changes as a reflection of complement activation during EC in sheep. In contrast no increase in TXB2 levels and no changes in hemodynamics are observed with HFAK-MC. The leukopenia and granulocytopenia in the latter is much less pronounced and probably reflects the phenomenon "frustrated phagocytosis".