Assessing Collagen Deposition During Aging in Mammalian Tissue and in Caenorhabditis elegans

: Proper collagen homeostasis is essential for development and aging of any multicellular organism. During aging, two extreme scenarios are commonly occurring: a local excess in collagen deposition, for instance during fibrosis, or a gradual overall reduction of collagen mass. Here, we describe a histological and a colorimetric method to assess collagen levels in mammalian tissues and in the nematode Caenorhabditis elegans. The first method is the polychrome Herovici staining to distinguish between young and mature collagen ratios. The second method is based on hydroxyproline measurements to estimate collagen protein levels. In addition, we show how to decellularize the multicellular organism C. elegans in order to harvest its cuticle, one of the two major extracellular matrices, mainly composed of collagen. These methods allow assessing collagen deposition during aging either in tissues or in whole organisms.