The prospects of health and longevity from the inhibition of the Maillard reaction in vivo

The Collagen Suprafamily: From Biosynthesis to Advanced Biomaterial Development

Collagen is the oldest and most abundant extracellular matrix protein that has found many applications in food, cosmetic, pharmaceutical, and biomedical industries. First, an overview of the family of collagens and their respective structures, conformation, and biosynthesis is provided. The advances and shortfalls of various collagen preparations (e.g., mammalian/marine extracted collagen, cell-produced collagens, recombinant collagens, and collagen-like peptides) and crosslinking technologies (e.g., chemical, physical, and biological) are then critically discussed. Subsequently, an array of structural, thermal, mechanical, biochemical, and biological assays is examined, which are developed to analyze and characterize collagenous structures. Lastly, a comprehensive review is provided on how advances in engineering, chemistry, and biology have enabled the development of bioactive, 3D structures (e.g., tissue grafts, biomaterials, cell-assembled tissue equivalents) that closely imitate native supramolecular assemblies and have the capacity to deliver in a localized and sustained manner viable cell populations and/or bioactive/therapeutic molecules. Clearly, collagens have a long history in both evolution and biotechnology and continue to offer both challenges and exciting opportunities in regenerative medicine as nature's biomaterial of choice.

An Original Approach to Aging: An Appreciation of Fritz Verzár’s Contribution in the Light of the Last 50 Years of Gerontological Facts and Thinking

The motivation of this review is the 120th anniversary of the birth of Fritz Verzár, founder of experimental gerontology. His major contributions to aging research are shortly reviewed and re-evaluated in the light of modern gerontological research. Verzár undertook aging research after his retirement from the Chair of Physiology at the Medical Faculty of Basel. His first experiments on aging of the rat tail tendon revealed an important mechanism of aging: an exponential increase of cross-linking of collagen fibres. This observation, correctly interpreted by Verzár as a new age-dependent mechanism, was shown later to be attributed to the Maillard reaction, the non-enzymatic glycosylation of protein (and nucleotide bases) amino groups followed by evolution of the reaction to advanced glycation end products (AGEs) involved in a number of harmful reactions. Many of these reactions were shown to be mediated by receptors recognizing AGE products (RAGEs). This was the first example of a post-synthetic (post-translational) reaction involved in the aging of biological macromolecules, especially those of the extracellular matrix. Verzár extended the research activity of his team to several other aspects of aging research, such as loss of muscular strength, nutritional requirements at high altitude, cell loss with aging, and ultrastructural studies, and started also the first longitudinal clinical study of aging in a Basel population. Modern gerontological research confirmed and extended Verzár's observations. His work on collagen cross-linking by glycation became of paramount importance in recent times because of the rapid increase of diabetes type II, combined with the metabolic syndrome, one of the major pathologies of modern times.

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.