Abstract
Many liver sinusoidal endothelial cell (LSEC)-dependent processes, including drug-induced liver injury, ischemia-reperfusion injury, acute and chronic rejection, fibrosis, and the HELLP (hemolytic anemia, elevated liver enzymes, low platelet count) syndrome, may have a lobular distribution. Studies of the mechanism of this distribution would benefit from a reliable method to isolate LSEC populations from different regions. We established and verified a simple method to isolate periportal, midlobular, and centrilobular LSEC. Three subpopulations of LSEC were isolated by immunomagnetic separation on the basis of CD45 expression. Flow cytometry showed that 78.2 ± 2.3% of LSEC were CD45 positive and that LSEC could be divided into CD45 bright (28.6 ± 2.7% of total population), dim (49.6 ± 1.0%), and negative populations (21.8 ± 2.3%). Immunohistochemistry confirmed that in vivo expression of CD45 in LSEC had a lobular distribution with enhanced CD45 staining in periportal LSEC. Cell diameter, fenestral diameter, number of fenestrae per sieve plate and per cell, porosity, and lectin uptake were significantly different in the subpopulations, consistent with the literature. Endocytosis of low concentrations of the LSEC-specific substrate, formaldehyde-treated serum albumin, was restricted to CD45 bright and dim LSEC. Acetaminophen was more toxic to the CD45 dim and negative populations than to the CD45 bright population. In conclusion, CD45 is highly expressed in periportal LSEC, low in midlobular LSEC, and negative in centrilobular LSEC, and this provides an easy separation method to isolate LSEC from the three different hepatic regions. The LSEC subpopulations obtained by this method are adequate for functional studies and drug toxicity testing.