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Objective: To test a novel gene carrier, named polyethyleneimine nanogel particles (PEI-NP), for delivering the mircroRNA (miRNA) into Kupffer cells (KCs) for silencing the expression of nuclear transcription factor κB (NF-κB) P65., Methods: The capacity of PEI-NPs to carry miRNA was tested by gel electrophoresis. RAW264.7 cell line was transfected with the cationic polymers which mixed together PEI-NP and miRNA. Then, the cytotoxicity of the RAW264.7 cells was detected by cell counting kit-8 (CCK-8); the cell apoptosis and transfection efficiency were analyzed by flow cytometry combined with annexin V-FITC/PI staining; the gene and protein levels of NF-κB P65 were determined respectively by real-time quantitative PCR (qRT-PCR) and Western blotting. The distribution of the cationic polymers in RAW264.7 cells and liver KCs was observed by transmission electron microscope (TEM). The protein level of NF-κB P65 in KCs was detected by immunohistochemistry., Results: PEI-NPs were able to completely combine with miRNA at the least mass ratio of 20:1. The highest transfection efficiency of 48 hours was (33.63±1.94)% in vitro. The protein level of NF-κB P65 at 48 hours of PEI-NP/miRNA transfection into RAW264.7 cells was significantly inhibited. TEM showed the cationic polymers in RAW264.7 cytoplasm and only in KCs of liver tissue after transfection. Immunohistochemistry indicated that the protein expression of NF-κB P65 in KCs was significantly lower than that in control group., Conclusion: Macrophages and KCs were successfully transfected with the cationic polymers in vitro and in vivo, respectively. The expression of NF-κB P65 was knocked down significantly after transfection.

Objective: To explore possible mechanisms of hepatic fibrosis by investigating the ultrastructural dynamic changes of liver tissue, especially several kinds of cells related to hepatic fibrosis., Methods: Murine schistosomal hepatic fibrosis model was established by infecting mice with Schistosoma japonicum cercariae. Routine transmission electron microscopy was used to observe the liver tissue. H.E. staining was used for examining the pathological changes., Results: H.E. staining showed that the model was established successfully. Ultrastructural observation showed that at the 6th week after infection, the necrosis of hepatocytes around the acute granulomas occurred; the number of sinusoidal endothelial fenestrae and vitamin A droplets in fat-storing cells decreased; large phagosomes and rough endoplasmic reticulum could be seen in the cytoplasm of Kupffer's cells. At the 8th week, steatosis was found in some hepatocytes, some microvilli emerged on a few inter-hepatocytic surfaces and the inter-hepatocytic spaces were enlarged. Large collagen fibrillar bundles filled in the perisinusoidal spaces, and capillarization of hepatic sinusoids was observed. Secretory vesicles filled with collagen fibrils appeared in the cytoplasm of fat-storing cells with large amount of collagenous fiber bundles surround the cells. Rough endoplasmic reticulum increased in Kupffer's cells. At the 10th week, fat-storing cells were activated and transformed into myofibroblasts. At the 12th week, the number of myofibroblasts decreased but that of fibroblasts and fiber cells increased., Conclusion: Activation of fat-storing cells and transformation from fat-storing cells into myofibroblasts are the critical link in the development of hepatic fibrogenesis following schistosome infection. Kupffer's cells, necrotic hepatocytes and sinusoidal endothelial cells may relate to the activation of fat-storing cells. Capillarization of hepatic sinusoids possibly accelerates the development of hepatic fibrosis.

Liver regeneration model following partial hepatectomy was used to study the effect and mechanism of estrogen on hepatocyte regeneration of rats. Each animal in the experimental groups received a single injection of diethylstilbestrol (DES) subcutaneously. Results showed that estrogen had a remarkable promoting effect on hepatocyte regeneration. Both 3H-TdR labelling and mitosis indices of hepatocytes in the experimental groups increased markedly. In DES-treated rats, synthesis of estrogen receptor of hepatocyte increased gradually and the translocation of ER from cytoplasm to nucleus was also enhanced at the same time, indicating that the mechanism of DES on hepatocyte regeneration consisted promoting of the interaction of ER and nucleus. There was no statistically significant difference (P greater than 0.05) found in the number of Kupffer cells between all the experimental and their corresponding control groups. But in ultrastructure, Kupffer cells of animals in the experimental groups presented increase of cell size with abundant cytoplasm; longer and more pseudopodia as well as phagolysosomes, suggesting that DES could activate Kupffer cell and promote its function. The relationship between Kupffer cells and liver regeneration is discussed.