Advanced Glycation End-products are Retained in Decellularized Muscle Matrix Derived from Aged Skeletal Muscle

Advanced glycation end-products (AGEs) accrue on skeletal muscle collagen in old age, stiffening the matrix and increasing inflammation. Whether decellularized biomaterials derived from aged muscle would suffer from increased AGE cross-links is unknown. We hypothesized that DMM from old muscle would have increased collagen, collagen cross-linking, stiffness, and AGEs. We isolated, decellularized, and characterized gastrocnemii of 1-month, 2-month, and 20-month old C57BlJ6 mice to determine age-dependent changes to collagen in muscle and decellularized muscle matrix (DMM). Total hydroxyproline and soluble hydroxyproline after proteinase K digestion were measured to assay collagen levels and cross-linking, respectively. Muscle fiber and DMM stiffness was determined using atomic force microscopy (AFM).  AGE ELISAs were used to test AGE levels, and the effect of AGE cross-link breaker ALT-711 on DMM was tested. We determined age-dependent increases in collagen amount, cross-linking, and general stiffness are retained on DMM. DMM from old muscle was stiffer compared to younger groups according to shifts in AFM modulus distribution. We measured an increase in AGE-specific cross-links with old age in whole muscle and observed that these changes are countered in DMM by AGE cross-link breaker ALT-711. Future study investigating and countering the biological effects of old age on DMM is warranted.