In connective tissues there is a clear link between increasing age and degeneration. Advanced glycation end-products (AGEs) are believed to play a central role. AGEs are sugarinduced non-enzymatic crosslinks which accumulate in collagen with age and diabetes, altering tissue mechanics and cellular function. Despite ample correlative evidence linking collagen glycation to tissue degeneration, little is known how AGEs impact cell-matrix interactions, limiting therapeutic options. One reason for this limited understanding is AGEs are typically induced using high concentrations of ribose which decrease cell viability, making it impossible to investigate cellmatrix interactions. The objective of this study was to develop a system to trigger AGE accumulation while maintaining cell viability. Materials and Methods:Using cell-seeded high density collagen gels, we investigated the effect of two systems for AGE induction, ribose at low concentrations (30, 100, and 200 mM) over 15 days of culture and riboflavin (0.25 mM and 0.75mM) induced with blue light for 40 seconds (riboflavin-465 nm). Results:We found ribose and riboflavin-465 nm treatment produces fluorescent AGE quantities which match and/or exceed human fluorescent AGE levels for various tissues, ages, and diseases, without affecting cell viability or metabolism. Interestingly, a 40 second treatment of riboflavin-465 nm produced similar levels of fluorescent AGEs as 3 days of 100 mM ribose treatment.Conclusions: Riboflavin-465 nm is a promising method to trigger AGE crosslinks on demand in vivo or in vitro without impacting cell viability and offers potential for unraveling the mechanism of AGEs in age and diabetes related tissue damage.

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In connective tissues there is a clear link between increasing age and degeneration. It is believed advanced glycation end-products (AGEs) play a central role in this degeneration. AGEs are sugar induced non-enzymatic crosslinks which accumulate in collagen with age and diabetes, altering tissue mechanics and cellular function. Despite ample correlative evidence linking collagen glycation to degeneration, little is known how AGEs impact cell-matrix interactions, limiting therapeutic options. One reason for this limited understanding is AGEs are typically induced in vitro using high concentrations of ribose which decrease cell viability and make it impossible to investigate cell-matrix interactions. The objective of this study was to develop a system to trigger AGE accumulation while maintaining cell viability. Using cell-seeded high density collagen gels, we investigated the effect of two different systems for AGE induction, ribose at low concentrations (30, 100, and 200 mM) over 15 days of culture and riboflavin (0.25 mM and 0.75mM) induced with blue light for 40 seconds. We found ribose and riboflavin with blue light are capable of producing a wide range of AGE crosslinks which match and/or exceed reported human AGE levels for various tissues, ages, and diseases, without affecting cell viability and metabolism. Interestingly, a single 40 second treatment of riboflavin and blue light produced similar levels of AGEs as 3 days of 100 mM ribose treatment and matched aged mouse tendon AGE levels. This riboflavin treatment option is an exciting means to trigger AGE crosslinks on demand in vivo or in vitro without impacting cell metabolism or viability and holds great promise for further unraveling the mechanism of AGEs in age and diabetes related tissue degeneration.