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Huang Y.-W.,National Taiwan University | Huang Y.-W.,U.S. Food and Drug Administration | Chiu C.-C.,National Taiwan University | Liang J.-D.,National Taiwan University | And 5 more authors.
PLoS ONE | Year: 2015

An appropriate liver-specific progenitor cell marker is a stepping stone in liver regenerative medicine. Here, we report brain isoform glycogen phosphorylase (GPBB) as a novel liver progenitor cell marker. GPBB was identified in a protein complex precipitated by a monoclonal antibody Ligab generated from a rat liver progenitor cell line Lig-8. Immunoblotting results show that GPBB was expressed in two liver progenitor cell lines Lig-8 and WB-F344. The levels of GPBB expression decreased in the WB-F344 cells under sodium butyrate (SB)-induced cell differentiation, consistent with roles of GPBB as a liver progenitor cell marker. Short hairpin RNA (shRNA)-mediated GPBB knockdown followed by glucose deprivation test shows that GPBB aids in liver progenitor cell survival under low glucose conditions. Furthermore, shRNA-mediated GPBB knockdown followed by SB-induced cell differentiation shows that reducing GPBB expression delayed liver progenitor cell differentiation. We conclude that GPBB is a novel liver progenitor cell marker, which facilitates liver progenitor cell survival under low glucose conditions and cell differentiation. © 2015 Huang et al.

Chiang T.-S.,National Taiwan University | Yang K.-C.,Taipei Medical University | Zheng S.-K.,National Taiwan University Hospital | Chiou L.-L.,Liver Disease Prevention and Treatment Research Foundation | And 6 more authors.
Biomaterials | Year: 2012

A reliable, reproducible, and convenient in vitro platform for drug metabolism determination and toxicity prediction is of tremendous value but still lacking. In the present study, a collection of 24 hepatic transcription factors and nuclear receptors in different combinations were surveyed, and 10 among them were finally selected to induce the expression and enzyme activities of cytochrome P450 (CYP) 3A4, 1B1, and 2C9 in human dermal fibroblasts (HDFs). The expression and activities of these CYPs in the induced HDFs were higher than those in commonly used hepatoma cell lines. High CYP expression and activities could be further enhanced by culturing the induced HDFs either as spheroids or into several kinds of scaffolds, particularly the tri-copolymer scaffold composed of gelatin, chondroitin and hyaluronan. More strikingly, there showed a synergistic effect of seeding and culturing the spheroids into the tri-copolymer scaffold. Scanning electron microscopy and confocal microscopy disclosed well accommodation of these spheroids inside the scaffolds and displayed a high survival rate. Moreover, the spheroid/scaffold constructs could metabolize an anti-hypertension drug nifedipine into oxidized nifedipine, showing their applicability in studying drug metabolism. This study presents a strategy to induce the expression and enzyme activities of critical CYPs in HDFs, and may have potential to establish an in vitro platform to study drug metabolism and to predict the possible human risk of drug toxicity. © 2012 Elsevier Ltd.

Chiang T.-S.,National Taiwan University | Yang K.-C.,Taipei Medical University | Wu Y.-M.,National Taiwan University Hospital | Lai H.-S.,National Taiwan University Hospital | And 7 more authors.
Process Biochemistry | Year: 2014

Among the cytochrome P 450 (CYP) enzymes, CYP3A4 is most abundantly existed and metabolizes most of the drugs. We have shown human dermal fibroblasts (HDFs) express low levels of CYPs, but could be engineered to express much higher levels to be used as drug metabolism prediction. To seek better cell source for engineering, the basal mRNA expression and enzyme activities of CYP3A4 in HDFs (n = 5), bone marrow-derived mesenchymal stem cells (BMMSCs, n = 7), and adipose-derived stem cells (ADSCs, n = 3) were compared. The basal CYP3A4 expression and activity in BMMSCs and ADSCs were significantly higher than in HDFs. However, the coefficient of variation of CYP3A4 expression was very high in each cell type. Comparing the expression levels of 4 regulators glucocorticoid receptor, pregnane X receptor (PXR), hepatocyte nuclear factor 4α, and hydrocarbon receptor nuclear translocator in the total 15 cell samples, we found the only basal PXR expression was significantly correlated with CYP3A4 expression. The gender and age of patients were not significant determinants in the expressions of PXR and CYP3A4. In conclusion, BMMSCs and ADSCs expressed higher levels of CYP3A4 than HDFs and the expression of CYP3A4 might be mainly determined by basal PXR expression. © 2014 Elsevier B.V. All rights reserved.

Wu C.-H.,National Taiwan University | Huang T.-Y.,National Taiwan University | Chen B.-S.,National Taiwan University Hospital | Chiou L.-L.,Liver Disease Prevention and Treatment Research Foundation | And 3 more authors.
PLoS ONE | Year: 2015

Although still debated, limb regeneration in salamanders is thought to depend on the dedifferentiation of remnant tissue occurring early after amputation and generating the progenitor cells that initiate regeneration. This dedifferentiation has been demonstrated previously by showing the fragmentation of muscle fibers into mononucleated cells and by revealing the contribution of mature muscle fibers to the regenerates by using lineage-tracing studies. Here, we provide additional evidence of dedifferentiation by showing that Pax7 (paired-box protein-7) transcripts are expressed at the ends of remnant muscle fibers in axolotls by using in situ hybridization and by demonstrating the presence of Pax7+ muscle-fiber nuclei in the early bud and mid-bud stages by means of immunohistochemical staining. During the course of regeneration, the remnant muscles did not progress; instead, muscle progenitors migrated out from the remnants and proliferated and differentiated in the new tissues at an early stage of differentiation. The regenerating muscles and remnant muscles were largely disconnected, and this left a gap between them until extremely late in the late stage of differentiation, at which point the new and old muscles connected together. Notably, Pax7 transcripts were detected in the regions of muscles that faced these gaps; thus, Pax7 expression might indicate dedifferentiation in the remnant-muscle ends and partial differentiation in the regenerating muscles. The roles of this long-duration dedifferentiation in the remnants remain unknown. However, the results presented here could support the hypothesis that long-duration muscle dedifferentiation facilitates the connection and fusion between the new and old muscles that are both in an immature state; this is because immature Pax7+ myoblasts readily fuse during developmental myogenesis. © 2015 Wu et al.

Li F.-C.,National Taiwan University | Huang G.-T.,National Taiwan University Hospital | Lin C.-J.,National Taiwan University | Wang S.-S.,National Taiwan University | And 8 more authors.
Cell Death and Disease | Year: 2011

Morphological changes of hepatocyte death have so far only been described on cells in culture or in tissue sections. Using a high-resolution and high-magnification multiphoton microscopic system, we recorded in living mice serial changes of acetaminophen (APAP)-induced hepatocyte necrosis in relevance to metabolism of a fluorogenic bile solute. Initial changes of hepatocyte injury included basal membrane disruption and loss of mitochondrial membrane potential. An overwhelming event of rupture at adjacent apical membrane resulting in flooding of bile into these hepatocytes might ensue. Belbs formed on basal membrane and then dislodged into the sinusoid circulation. Transmission electron microscopy disclosed a necrotic hepatocyte depicting well the changes after apical membrane rupture and bile flooding. Administration of the antidote N-acetylcysteine dramatically reduced the occurrence of apical membrane rupture. The present results demonstrated a hidden but critical step of apical membrane rupture leading to irreversible APAP-induced hepatocyte injury. © 2011 Macmillan Publishers Limited All rights reserved.

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