Endothelial cells perform multiple physiological functions and are central to many pathological processes. The liver contains two distinct endothelial cell types: vascular and sinusoidal. Sinusoidal endothelial cells (SEC) are microvascular endothelial cells with a unique phenotype reminiscent of dendritic cells and a unique function as antigen-presenting cells for CD4+ T cells. Thus, SEC represent a new type of organ-resident "non-professional" antigen-presenting cell that appears to be involved in the local control of the immune response and the induction of immune tolerance in the liver. The hepatic microenvironment, including the portal venous constituents and soluble mediators from sinusoidal cell populations, tightly control antigen presentation by SEC to avoid immune-mediated damage. SEC express well-characterized surface receptors and differ morphologically and metabolically from large-vessel endothelia. Previous studies have shown that SEC are dynamic regulators of porosity that respond rapidly and locally to environmental zonal stimuli during liver regeneration. SEC dysfunction and structural alterations have far-reaching repercussions for the whole liver. HHSEC from ScienCell Research Laboratories are isolated from human liver. HHSEC are cryopreserved at passage one and delivered frozen. Each vial contains >5 x 105 cells in 1 ml volume. HHSEC are characterized by immunofluorescence with antibodies specific to vWF/Factor VIII and/or CD31 (PECAM1). HHSEC are negative for HIV-1, HBV, HCV, mycoplasma, bacteria, yeast and fungi. HHSEC are guaranteed to further expand for 5 population doublings under the conditions provided by ScienCell Research Laboratories. Note: HHSEC are not expected to proliferate many times in culture, so we recommend using cells for experiments at earliest passage after initial plating. Recommended Medium It is recommended to use Endothelial Cell Medium (ECM, Cat. #1001) for the culturing of HHSEC.