MAP1LC3B and thymus atrophy: mUCMSCs inhibit the expression of the aging-related genes p53 and P16 by promoting the expression of autophagy- and anti-oxidative stress-related genes, such as LC3b, becline1, P62, SOD1, Sirt1 and Sirt3, thereby increasing the level of autophagy in the thymus tissue, inhibiting apoptosis and exerting therapeutic effects on thymus atrophy.