Comparison of ex vivo and in vitro human fibroblast ageing models

Several studies have analyzed modulation of gene expression during physiological ageing with interesting, but often contradictory results, depending on the model used. In the present report we compare age-related metabolic and synthetic parameters in human dermal fibroblasts (HDF) isolated from young and old subjects (ex vivo ageing model) and cultured from early up to late cumulative population doublings (CPD) (in vitro ageing model) in order to distinguish changes induced in vivo by the aged environment and maintained in vitro, from those associated with cell senescence and progressive CPD. Results demonstrate that fibroblasts from aged donors, already at early CPD, exhibit an impaired redox balance, highlighting the importance of this parameter during ageing, even in the presence of standard environmental conditions, which are considered optimal for cell growth. By contrast, several proteins, as those related to heat shock response, or involved in endoplasmic reticulum and membrane trafficking, appeared differentially expressed only during in vitro ageing, suggesting that, at high CPD, the whole cell machinery becomes permanently altered. Finally, given the importance of the elastic component for a long-lasting connective tissue structural and functional compliance, this study focuses also on elastin and fibulin-5 synthesis and deposition, demonstrating a close relationship between fibulin-5 and ageing.

Research highlights▶ The phenotype of human dermal fibroblasts is differently modulated in the ex vivo and in the in vitro ageing models. ▶ Differences in fibroblast phenotype are mainly observed during in vitro ageing, independently from donor's age. ▶ Parameters of redox balance are markedly modified with in vitro ageing and changes depend also on donor's age. ▶ Extracellular elastin deposition is dramatically reduced with in vitro ageing and is associated to intracellular accumulation. ▶ Fibulin-5 represents a very sensitive ageing marker and may be also involved in the redox balance.