Chronological aging is defined as a time-dependent decline of tissue homeostasis which severely impacts skin. Understanding the mechanisms of skin aging is an active research area limited by the lack of relevant in vitro models. Being a component of aging, replicative or stress-induced senescence is repeatedly used to mimic skin aging in vitro, thus presenting only a partial view of the complexity of aging. Herein, we aimed to clarify whether primary normal human dermal fibroblasts retained age-related characteristics when cultured in 2D monolayer, and could be used as a relevant model for aging research. We compared three groups of fibroblasts isolated from different aged donors. We observed strongly decreased population doubling capacities, a reduced clonogenic ability, an impairment in extracellular matrix production together with modifications of respiratory metabolism with an increase in age. These disruptions were particularly marked when comparing fibroblasts isolated from old individuals (over 70 years old) to those isolated from young individuals (18-37 years old), while cells from middle-aged donors exhibited an intermediate profile. These alterations of cell features can be related to the signs of dermis aging, thus showing that cultured primary cells indeed retain some characteristics of the original tissue from which they were extracted.
Keywords: aging; clonogenicity; extracellular matrix; fibroblast; mitochondria; population doubling; skin.