Fritz Verzár was born 120 years ago: His contribution to experimental gerontology through the collagen research as assessed after half a century

F. Verzár's experiments on the age-dependent increase of cross-linking of rat tail tendons in the 1950s represented the first demonstration of age-dependent modifications of extracellular matrix (ECM) macromolecules. This discovery preceded by several years the demonstration of cell-aging and showed that body constituents considered as metabolically “inert” do exhibit age-dependent modifications at the molecular level. Progressively the physiological mechanisms of collagen cross-linking were elucidated and it became clear that this mechanism does not explain the Verzár phenomenon. It was progressively elucidated that the Maillard reaction was involved in the age-dependent cross-linking of collagen. The role of advanced glycation end products (AGEs) in collagen cross-linking, as well as their reaction with other macromolecules was convincingly demonstrated as an important factor of age-dependent modifications of cells and tissues. The Verzár phenomenon completed by the detailed chemistry of the Maillard reaction became thus a dominant paradigm in tissue aging. Verzár's name and discovery should therefore remain associated with these important progresses in aging research. The purpose of this review is to recall some of the details of Verzár's work which paved the way to his discovery and extended well beyond collagen aging.