Histological species differences among chickens, rats, and mice in experimental cholestasis by bile duct ligation

Cholestasis is a hepatic disease reported in humans, dogs, and chickens and is characterized by various signs. Bile duct ligation (BDL) is a standard model for research in cholestasis in male rats and mice. However, the timing and degree of structural changes in BDL-subjected liver differ in the two animal species. This study focused on chickens as a choice model for cholestasis. Specifically, we aimed to evaluate the features of BDL in hens and compare them with those in rats and mice. Eighteen hens, 19 female ICR mice, and 18 female SD rats were randomly divided into the sham-operated and BDL groups. At 2, 4, and 6 weeks after BDL, and 4 weeks after the sham operation, liver and blood samples were collected and analyzed histologically and biochemically. Histologically, bile duct proliferation in BDL-subjected livers was first observed in the chickens and then the rats and mice, whereas CD44-positive small hepatocytes were observed only in chickens in the BDL group. Biochemically, the mRNA expression of the hepatocyte growth factor was higher in BDL-subjected chickens, while Interleukin 6 expression was higher in the BDL-subjected rats and mice than in animals in the sham group. In addition, farnesoid X receptor mRNA expression was lower in the BDL-subjected chickens than in the sham chickens. The BDL group had significantly higher total bile acid blood concentration than the sham group. In conclusion, the signs of hepatopathy caused by BDL differ among animal species. Furthermore, we propose that compared to BDL-subjected mice and rats, BDL-subjected chickens are a novel cholestasis animal model that demonstrates severe hepatopathy and liver restructuring.

Monitoring Cultured Rat Hepatocytes Using RNA-Seq In Vitro

Compared to other techniques, RNA sequencing (RNA-Seq) has the advantage of having details of the expression abundance of all transcripts in a single run. In this study, we used RNA-Seq to monitor the maturity and dynamic characteristics of in vitro hepatocyte cultures. Hepatocytes, including mature hepatocytes and small hepatocytes, were analyzed in vitro using RNA-Seq and quantitative polymerase chain reaction (qPCR). The results demonstrated that the gene expression profiles measured by RNA-Seq showed a similar trend to the expression profiles measured by qPCR, and can be used to infer the success of in vitro hepatocyte cultures. The results of the differential analysis, which compared mature hepatocytes against small hepatocytes, revealed 836 downregulated and 137 upregulated genes. In addition, the success of the hepatocyte cultures could be explained by the gene list screened from the adopted gene enrichment test. In summary, we demonstrated that RNA-Seq could become an effective method for monitoring the whole transcriptome of hepatocyte cultures and provide a more comprehensive list of factors related to the differentiation of small hepatocytes into mature hepatocytes. This monitoring system not only shows high potential in medical applications but may also be a novel method for the clinical diagnosis of liver-related diseases.

Identification and ultrastructural characterization of small hepatocyte-like cells in birds

Small hepatocytes (SH) have been identified in regenerative organs and have been proposed to be hepatocyte progenitor cells. Their characteristic presence in birds, and their maturation into functional and mature hepatocytes, have not yet been elucidated. We previously demonstrated the appearance of chicken SH, which express CD44, in a model of chicken hepatopathy treated with bile duct ligation (BDL). We expanded on our previous research and performed a detailed study of the ultrastructure of chicken SH. Four weeks after BDL, we observed chicken SH with high electron density cytoplasm and with colony formation. In the chicken SH, electron microscopical analysis found no formation of tight junctions and no glycogen. Ultrastructural analysis also revealed the existence of various types of chicken SH with characteristics lying between those of chicken SH with colony formation and mature hepatocytes. The analysis of immunoelectron microscopy showed CD44 expressed on the surface of the extensive SH-like cells in the hepatic lamina. These results suggest that the expression of CD44 changes according to the differentiated stage of SH in a chicken BDL model.