C57BL/6 Mouse Liver Sinusoidal Endothelial Cells

Hypoxia Promotes the Proliferation of Mouse Liver Sinusoidal Endothelial Cells: miRNA–mRNA Expression Analysis

In the early stage of liver regeneration (LR), hepatocytes and liver sinusoidal endothelial cells (LSECs) proliferate under the conditions of hypoxia. However, the role and molecular mechanism of LSECs under hypoxic conditions are still not fully understood. In this study, Qing’s team screened the miRNA–mRNA regulatory network involved in the proliferation of hypoxic LSECs.

First, they detected the proliferation of LSECs under hypoxic conditions to clarify the relationship between LSECs and liver regeneration in the early stage due to the hypoxic microenvironment. As shown in Figure1, EdU staining revealed more proliferation of LSECs in hypoxic conditions for 24 hours compared to normoxic conditions. These data suggest that hypoxia promotes LR through LSECs. Next, to explore the potential mechanism of hypoxia on LSEC proliferation, they performed high-throughput sequencing on LSECs under hypoxia (Group B) and normoxia (Group A), with n=3 per group. A total of 1,837 differentially expressed (DE) mRNAs (including 1,056 upregulated and 781 downregulated mRNAs) and 17 DE miRNAs (including 7 upregulated and 10 downregulated miRNAs) were identified. The target genes of DE miRNAs predicted by miRanda and TargetScan were intersected with DE mRNAs to obtain negatively correlated miRNA–mRNA pairs.

LSEC Morphology and Fenestration in Glmpgt/gt Livers in situ

Liver sinusoidal endothelial cells (LSECs) clear blood-borne waste through scavenger receptors, yet little is known about the role of LSECs in liver disease. Glmpgt/gt mice develop a chronic liver injury and fibrosis due to the deficiency in lysosomal membrane protein transport and represent an ideal model to study LSEC dysfunction. Here, Antwi et al. determined the role of Glmp in LSEC scavenger function and morphology.

To investigate LSEC morphology in Glmpgt/gt mice, liver tissues from 4-month-old (n=4) and 9–10-month-old (n=4) Glmpgt/gt male mice and WT controls (n=4, 4–6 months old) were scanned by EM. Tissues were sorted based on their median "% FITC-fluorescence area per liver tissue area". The LSECs in WT livers were highly fenestrated and possessed sieve plates with few gaps (>400 nm holes) (Fig. 2A1 and A2). In Glmpgt/gt, LSECs also retained fenestrations (circled) in the areas with fibrosis and inflammatory cell infiltration (Fig. 2B–D). Although, increased gaps were found near damaged hepatocytes and immune cells (Fig. 2C1, D1 and D2). Thick-walled non-fenestrated capillaries were also found in the areas with severe hepatocyte necrosis and destroyed sinusoids that possibly reflect neovascularization (Fig. 2D3).