In Vitro Tests

 Collagen, Elastin and Hyaluronic Acid Production

These assays will typically use human three dimensional tissue equivalents containing both an epidermal layer of keratinocytes and a dermal layer of fibroblasts.  Alternatively, cultured fibroblasts can be used.  Collagen synthesis can be quantified by measuring the amount of procollagen fragments that accumulated in the culture media of the tissues, while elastin and hyaluronic acid are directly measured.  Histology samples of human full thickness tissue equivalents are shown below.

Verhoeff's Elastic Stain: collagen in the dermis is stained red, cell nuclei are stained black and the epidermis is stained dark brown.		Alcian Blue (pH 2.5) Stain: Hyaluronic acid in the dermis is stained blue.  Nuclear fast red was used to counterstain the epidermis.