Browsing by Subject "Hepatocytes"

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Open Access
Characterization of a canine model of glycogen storage disease type IIIa.
(Dis Model Mech, 2012-11) Yi, Haiqing; Thurberg, Beth L; Curtis, Sarah; Austin, Stephanie; Fyfe, John; Koeberl, Dwight D; Kishnani, Priya S; Sun, Baodong
Glycogen storage disease type IIIa (GSD IIIa) is an autosomal recessive disease caused by deficiency of glycogen debranching enzyme (GDE) in liver and muscle. The disorder is clinically heterogeneous and progressive, and there is no effective treatment. Previously, a naturally occurring dog model for this condition was identified in curly-coated retrievers (CCR). The affected dogs carry a frame-shift mutation in the GDE gene and have no detectable GDE activity in liver and muscle. We characterized in detail the disease expression and progression in eight dogs from age 2 to 16 months. Monthly blood biochemistry revealed elevated and gradually increasing serum alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) activities; serum creatine phosphokinase (CPK) activity exceeded normal range after 12 months. Analysis of tissue biopsy specimens at 4, 12 and 16 months revealed abnormally high glycogen contents in liver and muscle of all dogs. Fasting liver glycogen content increased from 4 months to 12 months, but dropped at 16 months possibly caused by extended fibrosis; muscle glycogen content continually increased with age. Light microscopy revealed significant glycogen accumulation in hepatocytes at all ages. Liver histology showed progressive, age-related fibrosis. In muscle, scattered cytoplasmic glycogen deposits were present in most cells at 4 months, but large, lake-like accumulation developed by 12 and 16 months. Disruption of the contractile apparatus and fraying of myofibrils was observed in muscle at 12 and 16 months by electron microscopy. In conclusion, the CCR dogs are an accurate model of GSD IIIa that will improve our understanding of the disease progression and allow opportunities to investigate treatment interventions.
Open Access
Generation of Functional Hepatocyte-Like Cells (HLCs) from Human Adipose-Derived Stem Cells (ADSCs) in 2D and 3D
(2019) Arinda, Beryl Ngabirano
Mortality and morbidity rates caused by acute liver failure (ALF), acute-on-chronic liver failure (ACLF) and chronic liver disease continue to rise because of drug induced failure or viral hepatitis, currently with 2,000 cases annually in the United States. Liver transplantation is the only intervention that has shown the most promising patient outcomes, but this approach has major shortcomings like shortage of donor livers, lifelong immunosuppression and a risk of organ rejection after transplantation. Additionally, with rapid liver deterioration and subsequent multi-organ failure characterized by ALF and ACLF conditions, there are high mortality rates as patients await a liver transplant or wait for their livers to regenerate. As such, bioartificial liver support devices provide an alternative to improve patient survival through either offloading liver functions to allow for liver regeneration or by allowing the patient time to receive a liver transplant. These bioartificial liver support devices are designed to perform essential liver functions through incorporation of an active cellular component that performs the liver functions and their success is therefore heavily reliant on the performance of the incorporated cell lines. Because of this, limited sources of these characteristic cell lines with hepatic function is a great challenge being faced in the research and development of the devices.

Adipose-derived stem cells (ADSCs) are a great candidate as a stem cell source for differentiation of hepatocyte-like cells because they can be easily obtained in large quantities with little donor site morbidity or discomfort and have been successfully differentiated into multiple cell lineages. In this study, we investigate the possibility of differentiating human ADSCs into functional hepatocyte-like cells. Furthermore, we investigated the ability to differentiate ADSCs into hepatocyte-like cells in both 2D and 3D environments. We found that induced ADSCs can produce high levels of some hepatocyte functions, like albumin secretion. However, other functions, like urea secretion and cytochrome P450 metabolic activity, while present, are not yet at sufficient levels to be comparable to primary hepatocytes.
Open Access
Hepatic mitochondrial dysfunction is a feature of Glycogen Storage Disease Type Ia (GSDIa).
(Scientific reports, 2017-03) Farah, Benjamin L; Sinha, Rohit A; Wu, Yajun; Singh, Brijesh K; Lim, Andrea; Hirayama, Masahiro; Landau, Dustin J; Bay, Boon Huat; Koeberl, Dwight D; Yen, Paul M
Glycogen storage disease type Ia (GSDIa, von Gierke disease) is the most common glycogen storage disorder. It is caused by the deficiency of glucose-6-phosphatase, an enzyme which catalyses the final step of gluconeogenesis and glycogenolysis. Clinically, GSDIa is characterized by fasting hypoglycaemia and hepatic glycogen and triglyceride overaccumulation. The latter leads to steatohepatitis, cirrhosis, and the formation of hepatic adenomas and carcinomas. Currently, little is known about the function of various organelles and their impact on metabolism in GSDIa. Accordingly, we investigated mitochondrial function in cell culture and mouse models of GSDIa. We found impairments in oxidative phosphorylation and changes in TCA cycle metabolites, as well as decreased mitochondrial membrane potential and deranged mitochondrial ultra-structure in these model systems. Mitochondrial content also was decreased, likely secondary to decreased mitochondrial biogenesis. These deleterious effects culminated in the activation of the mitochondrial apoptosis pathway. Taken together, our results demonstrate a role for mitochondrial dysfunction in the pathogenesis of GSDIa, and identify a new potential target for the treatment of this disease. They also provide new insight into the role of carbohydrate overload on mitochondrial function in other hepatic diseases, such as non-alcoholic fatty liver disease.
Open Access
TWEAK/Fn14 signaling is required for liver regeneration after partial hepatectomy in mice.
(PLoS One, 2014) Karaca, Gamze; Swiderska-Syn, Marzena; Xie, Guanhua; Syn, Wing-Kin; Krüger, Leandi; Machado, Mariana Verdelho; Garman, Katherine; Choi, Steve S; Michelotti, Gregory A; Burkly, Linda C; Ochoa, Begoña; Diehl, Anna Mae
BACKGROUND & AIMS: Pro-inflammatory cytokines are important for liver regeneration after partial hepatectomy (PH). Expression of Fibroblast growth factor-inducible 14 (Fn14), the receptor for TNF-like weak inducer of apoptosis (TWEAK), is induced rapidly after PH and remains elevated throughout the period of peak hepatocyte replication. The role of Fn14 in post-PH liver regeneration is uncertain because Fn14 is expressed by liver progenitors and TWEAK-Fn14 interactions stimulate progenitor growth, but replication of mature hepatocytes is thought to drive liver regeneration after PH. METHODS: To clarify the role of TWEAK-Fn14 after PH, we compared post-PH regenerative responses in wild type (WT) mice, Fn14 knockout (KO) mice, TWEAK KO mice, and WT mice treated with anti-TWEAK antibodies. RESULTS: In WT mice, rare Fn14(+) cells localized with other progenitor markers in peri-portal areas before PH. PH rapidly increased proliferation of Fn14(+) cells; hepatocytic cells that expressed Fn14 and other progenitor markers, such as Lgr5, progressively accumulated from 12-8 h post-PH and then declined to baseline by 96 h. When TWEAK/Fn14 signaling was disrupted, progenitor accumulation, induction of pro-regenerative cytokines, hepatocyte and cholangiocyte proliferation, and over-all survival were inhibited, while post-PH liver damage and bilirubin levels were increased. TWEAK stimulated proliferation and increased Lgr5 expression in cultured liver progenitors, but had no effect on either parameter in cultured primary hepatocytes. CONCLUSIONS: TWEAK-FN14 signaling is necessary for the healthy adult liver to regenerate normally after acute partial hepatectomy.
Open Access
Viral factors induce Hedgehog pathway activation in humans with viral hepatitis, cirrhosis, and hepatocellular carcinoma.
(Lab Invest, 2010-12) Pereira, Tde A; Witek, RP; Syn, WK; Choi, SS; Bradrick, S; Karaca, GF; Agboola, KM; Jung, Y; Omenetti, A; Moylan, CA; Yang, L; Fernandez-Zapico, ME; Jhaveri, R; Shah, VH; Pereira, FE; Diehl, AM
Hedgehog (Hh) pathway activation promotes many processes that occur during fibrogenic liver repair. Whether the Hh pathway modulates the outcomes of virally mediated liver injury has never been examined. Gene-profiling studies of human hepatocellular carcinomas (HCCs) demonstrate Hh pathway activation in HCCs related to chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV). Because most HCCs develop in cirrhotic livers, we hypothesized that Hh pathway activation occurs during fibrogenic repair of liver damage due to chronic viral hepatitis, and that Hh-responsive cells mediate disease progression and hepatocarciongenesis in chronic viral hepatitis. Immunohistochemistry and qRT-PCR analysis were used to analyze Hh pathway activation and identify Hh-responsive cell types in liver biopsies from 45 patients with chronic HBV or HCV. Hh signaling was then manipulated in cultured liver cells to directly assess the impact of Hh activity in relevant cell types. We found increased hepatic expression of Hh ligands in all patients with chronic viral hepatitis, and demonstrated that infection with HCV stimulated cultured hepatocytes to produce Hh ligands. The major cell populations that expanded during cirrhosis and HCC (ie, liver myofibroblasts, activated endothelial cells, and progenitors expressing markers of tumor stem/initiating cells) were Hh responsive, and higher levels of Hh pathway activity associated with cirrhosis and HCC. Inhibiting pathway activity in Hh-responsive target cells reduced fibrogenesis, angiogenesis, and growth. In conclusion, HBV/HCV infection increases hepatocyte production of Hh ligands and expands the types of Hh-responsive cells that promote liver fibrosis and cancer.