IF methods were described previously (8 (link)). Antibodies used were: 1:100 rat anti-mouse CD31 antibody (BD, 550274), 1:200 Alexa Fluor® 488 goat anti-rat antibody (Invitrogen, A11006), and 1:500 monoclonal mouse anti-α-smooth muscle actin (SMA) Cy3 antibody (Sigma, C6198). Slides were mounted with Vectashield Hardset Mounting Medium with DAPI (Vector Labs) and imaged on a Zeiss CLSM 710 or 700 Spectral Confocal Laser Scanning Microscope.