Endothelial-specific expression of LKLF and claudin-5 in the normal human aorta.

(A) Overview of a section of the thoracic aorta of a 13-year-old female stained with nuclear fast red. Nonradioactive mRNA in situ hybridizations was performed on consecutive sections, using antisense riboprobes of LKLF (B,D,E), claudin-5 (H), cytochrome P450 1B1 (I), and the endothelial-specific marker von Willebrand factor (VWF) (C,F,G). The detection of the mRNA-probe hybrid results in a blue color associated with the nuclei. Panels E and G show no significant expression of the LKLF mRNA (E), whereas VWF (G) is consistently and specifically expressed in the endothelium of the entire specimen. Stacks of nuclei are visible because of the thickness of the sections (16 μm) and the conical shape of the branching artery. Claudin-5 was specifically expressed in the endothelium (H), but detection of the cytochrome P450 1B1 mRNA was too close to background hybridization levels (I).