Immunohistochemical characterization of in vitro human skin equivalents for skin aging
Marjolein Brouwer, Aeon Astron Europe BV, Leiden, the Netherlands
Background Skin ages with time in a complex process. During this process skin becomes wrinkled, dry, and irregularly pigmented. These changes are histologically visible. The dermis and epidermis lose their structural and functional characteristics. In the dermal compartment, there is a decreased deposition of ECM component which decreases skin elasticity. In the epidermis, less cell layers and loss of rete ridges are observed. In vitro skin equivalents are developed and characterized immunohistochemically to study the cellular processes that contribute to aging.
Methods In fibroblast derived matrix (FDM) models, fibroblasts were stimulated to produce their own ECM. On top of this dermal matrix, keratinocytes were seeded to differentiate into a functional epidermis. FDMs were cultured for two or eight weeks air-exposed, mimicking respectively young and aged skin, and immunohistochemically characterized for vital and aging specific biomarkers. Morphology and dermal and epidermal thickness were assessed.
Results Young and aged FDMs showed full epidermal stratification and basement membrane formation. Aged FDMs demonstrated less viable epidermal layers, decreased CD44 expression and increased number of a-SMA positive fibroblasts.
Conclusion Immunohistochemically, in vitro skin models showed similar expression of aging markers compared to native skin. Therefore this model can be used as a representative aging model.