No donor age effect of human serum on collagen synthesis signaling and cell proliferation of human tendon fibroblasts.

The aging process of tendon tissue is associated with decreased collagen content and increased risk for injuries. An essential factor in tendon physiology is transforming growth factor-β1 (TGF-β1), which is presumed to be reduced systemically with advanced age. The aim of this study was to investigate whether human serum from elderly donors would have an inhibiting effect on the expression of collagen and collagen-related genes as well as on cell proliferative capacity in tendon cells from young individuals. There was no difference in systemic TGF-β1 levels in serum obtained from young and elderly donors, and we found no difference in collagen expression when cells were subjected to human serum from elderly versus young donors. In addition, tendon cell proliferation was similar when culture medium was supplemented with serum of different donor age. These findings suggest that factors such as the cell intrinsic capacity or the tissue-specific environment rather than systemic circulating factors are important for functional capacity throughout life in human tendon cells.