Immunohistochemistry (IHC)

IHC was performed as previously described (Rittié et al. 2008) on 7-μm-thick frozen skin sections fixed in 2% paraformaldehyde or ice-cold acetone, using the following primary antibodies: anti-laminin-γ2 (ab1207 at a:2000, Abcam, Cambridge, MA); anti-collagen IV and –collagen VII (MAB1910 and MAB1345, both at 1:500, EMD Millipore, Billerica, MA). Slides were mounted with Supermount (Biogenex, Fremont, CA) or with ProLong Gold medium and coverslips (Thermo Fisher Scientific). Imaging was performed with an Axioscope 2 (Carl Zeiss, Thornwood, NY) equipped with a Spot digital camera (Spot Imaging Solutions, Sterling Heights, MI). A microscope micrometer (Thermo Fisher Scientific) was used during imaging for image calibration.