SIRT1 and osteoarthritis: Although human chondrocytes from osteoarthritis cartilage samples, human knee articular chondrocytes [63,64], and chondrosarcoma HTB-94 cells express SIRT1 [64], their expression decreases with age, contributing to a higher risk of osteoarthritis development in humans and mice [64,65]; this is due to a shift in chondrocyte activity toward catabolic proteolysis, increasing the rate of apoptosis, together with lower chondrogenic action [64], decreasing autophagy, and accelerating chondrocyte senescence [66].