HSEC from Creative Bioarray are isolated from human spleen. HSEC are cryopreserved at passage one and delivered frozen. Each vial contains >5 x 105 cells in 1 ml volume. HSEC are characterized by immunofluorescence with antibodies specific to VWF/Factor VIII and CD31 (P-CAM), and by uptake of DiI-Ac-LDL. HSEC are negative for HIV-1, HBV, HCV, mycoplasma, bacteria, yeast and fungi. HSEC are guaranteed to further expand for 15 population doublings under the conditions provided by Creative Bioarray.