Immunohistology was performed as described previously 16 (link). Briefly, skin OCT-embedded cryo-sections (7μm thick) were fixed in paraformaldehyde. Subsequently, the slides were incubated for 1 hour at room temperature with normal control serum followed by incubation of anti-elastin antibody (Abcam, Cambridge, MA, USA, cat#: ab77804). All sections were lightly counterstained with hematoxylin and were mounted with mounting media (Vector, Laboratories, CA, USA). To visualize elastic fiber, skin sections were stained by Verhoff van Geison staining, which is most commonly used for visualizing elastic fibers.