Alterations of biochemical and two-dimensional biomechanical properties ofhuman skin in diabetes mellitus as compared to effects of in vitro non-enzymatic glycation

Objective. The aim of this study was to evaluate whether multiaxial analysi s of diabetes-specific biomechanical changes generated in vitro by non-enzy matic glycation of human skin samples from healthy subjects reflect the cha nges seen in skin from subjects with diabetes mellitus. Design. Descriptive study. Background Non-enzymatic glycation of skin in vitro causes an incre ased stiffness comparable to in vivo changes seen in diabetic patients. The se changes are probably due to increased cross-linking of collagen molecule s, Methods. Skin specimens from 7 subjects with diabetes mellitus and 7 con trols (age range: 74-90) were analyzed for biomechanical changes using a mu ltiaxial tensile testing device. Control skins from healthy individuals in the age range of 50-65 yr were artificially glycated. One part of these sam ples was coincubated with the glycation inhibitor aminoguanidine. Glycation of tissues was determined by measuring fluorescence of solubilized samples . Multiaxial biomechanical analysis allows the determination of maximum (a( I)) and minimum elastic modulus (a(II)). These parameters describe the ampl itude of the elastic stress response, which is exponentially related to str ain. Results. Principal stresses, both maximum and minimum, were increased in skins from diabetic subjects as compared to controls. The increases of t he principal stresses were comparable to those obtained by in vitro glycati on of normal skins. Conclusion. These results, which can be detected unequi vocally with the multiaxial test mode, show that our in vitro model closely reflects changes in skin samples from individuals with diabetes mellitus. Aminoguanidine partially inhibited these as well as biochemical changes.