Purpose Recently, it has been emphasized that hepatic progenitor/oval cells (HPCs) are significantly involved in liver fibrogenesis. We evaluated the multipotential population of HPCs by transmission electron microscope (TEM), including relations with adherent hepatic nonparenchymal cells (NPCs) in rats with biliary fibrosis induced by bile duct ligation (BDL). Methods The study used 6-week-old Wistar Crl: WI(Han) rats after BDL for 1, 6, and 8 weeks. Results Current ultrastructural analysis showed considerable proliferation of HPCs in experimental intensive biliary fibrosis. HPCs formed proliferating bile ductules and were scattered in periportal connective tissue. We distinguished 4 main types of HPCs: 0, I, II (bile duct-like cells; most common), and III (hepatocyte-like cells). We observed, very seldom presented in literature, cellular interactions between HPCs and adjacent NPCs, especially commonly found transitional hepatic stellate cells (T-HSCs) and Kupffer cells/macrophages. We showed the phenomenon of penetration of the basement membrane of proliferating bile ductules by cytoplasmic processes sent by T-HSCs and the formation of direct cell-cell contact with ductular epithelial cells related to HPCs. Conclusions HPC proliferation induced by BDL evidently promotes portal fibrogenesis. Better understanding of the complex cellular interactions between HPCs and adjacent NPCs, especially T-HSCs, may help develop antifibrotic therapies in the future.
The obtained results suggest the beneficial anti-apoptotic potential of flunarizine and the anti-necrotic potential of cinnarizine against glutamate-induced death of cultured hippocampal neurons. Nimodipine can protect neurons against necrosis, but has an intensified adverse pro-apoptotic effect on cultured neurons in the experimental model of excitotoxic injury.
The pathogenesis of autoimmune hepatitis (AIH) is poorly understood. Up to now, little is known of the involvement of liver sinusoidal endothelial cells (LSECs), accounting for approximately 40% of nonparenchymal hepatic cells, in AIH morphogenesis in pediatric patients. The study objective was ultrastructural analysis of LSECs from pretreatment biopsies of 19 children, aged 4-17 years (14 girls), with clinically and histologically diagnosed AIH. Our study is the first to describe alterations in LSECs, from swelling to necrosis, demonstrating their important role in the morphogenesis and progression of pediatric AIH. Frequently damage to LSECs coexisted with significantly activated Kupffer cells, fibrogenesis and fibrosis, but not cirrhosis, accompanied by the appearance of transitional hepatic stellate cells. Interestingly, even though in half of the AIH children the sinusoidal vessels were found to undergo transformation of discontinuous into continuous endothelium showing features of defenestration, the true basement membrane did not form underneath. The fact that the basement membrane is not formed, even when LSECs are markedly damaged, may seem to indicate some regenerative capacities of these cells and lesion reversibility.
Our results suggest the protective potential of both studied nootropics against Aβ-induced death of cultured hippocampal neurons with more powerful neuroprotective effects of LEV.
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