Figure 1.

Cells isolated from the intima of healthy mouse aortas are endothelial cells (ECs). A, Graph represents relative expression of RNA normalized to the housekeeping gene B2M. RNA was isolated from mouse aortic endothelial cell (MAEC) preparations and whole aortas, from 3 animals each, and expression values are shown for individual mice. Normalized gene expression for the 2 EC markers von Willebrand factor (vWF) and platelet/endothelial cell adhesion molecule 1 (CD31) show significant enrichment in the intimal preparations and are nearly undetectable in the whole aorta samples, whereas the smooth muscle cell (SMC) protein marker ACTA2 is expressed to a much higher level in the whole aorta samples. Error bars show SD for 2 technical replicates. B, Relative transcription levels of 8 different smooth muscle cell protein markers and the EC marker CD31 in MAECs and human aortic endothelial cell (HAEC) cultures as determined by reverse transcription quantitative polymerase chain reaction, normalized to the housekeeping gene B2M. mRNA transcript levels for all SMC protein markers are present in the HAEC cultures, which have been confirmed as SMC free using protein markers and serve as a positive control for our purposes. SMC protein transcript levels for the mouse homologs of these genes show similar expression levels in our intimal preparations, indicating a confidence level of EC purity equal to that for HAEC cultures. Error bars show SE for 6 biological replicates for each sample set. t test: **P <0.01; and ***P <0.005.