Melatonin‐engineered MSCs‐exosomes deliver USP4 to stabilise ARNTL and inhibit clock rhythmic ferroptosis for enhanced flap survival. - Jiang, Xiaoqiong; Wang, Yu; Zhang, Xuanlong; Deng, Huiming; Fang, Liangyu; Tafadzwa, Chaire; Yao, Jiangnan; Chen, Hao; Ye, Anqi; Zhou, Kailiang; Ling, Xiangwei; Xiao, Jian (Clinical & Translational Medicine, 2026)