New approaches to skin photodamage histology—Differentiating 'good' versus 'bad' Elastin

BACKGROUND: Photodamage creates changes within the skin layers known as solar elastosis. This presents as fragmentation of collagen and elastin fibers, decreases in the extracellular matrix (ECM) ground substance, as well as hyaluronic acid decrease in the thinning epidermis. Traditional immunohistochemistry (IHC) staining has failed to differentiate degenerated elastin from new elastin fibers generated with various topical strategies. AIMS: A combination of stains that can offer a regenerative narrative distinguishing newly formed collagen and elastin from that of degenerated protein, thus distinguishing “good” vs “bad” elastin. METHODS: A series of stains were explored based on their ability to identify early regenerative changes within epidermal, dermal, and ECM areas to examine consistency of outcomes and reliability. RESULTS: A combination of Movat, fibrillin, elafin, and versican for elastogenesis and reversal of solar elastosis. CD44 for HA status (mainly epidermal) and Herovici stain for identifying early collagenesis in the ECM provides a comprehensive range of stains for identifying new elastin and collagen CONCLUSION: This suggested stain combination appears to offer an ideal collection of stains for identifying regenerative events within the skin layers.