Regeneration of chronic skin wounds in tissue is still a key challenge in regenerative medicine because of the accumulation of senescent cells and increasing secretion of "senescence-associated secretory phenotype"-(SASP) in the wound site. Recently, some studies have reported that small extracellular vesicles (sEVs) derived from stem cells can alleviate cellular senescence with very low risk of tumorigenesis and immune responses. As our previous studies have shown that urine-derived stem cells (USCs) can be obtained easily and noninvasively and sEVs derived from USCs (USC-sEVs) have capabilities of regenerating tissue injuries, using USC-sEVs to enhance chronic skin wound healing in aged tissue might be a feasible and efficient strategy. Therefore, in this study, the USC-sEVs were collected and firstly loaded in a human acellular amniotic membrane (HAAM) for controlled releasing and locating the USC-sEVs in the wound site before they were implanted into a chronic skin wound in aged mice. In vivo results showed that the USC-sEVs in HAAM could effectively accelerate the wound healing by ameliorating cellular senescence and reducing the secretion of SASP in the aged skin wounds. To elucidate the mechanism, USC-sEVs were used to in vitro culture human dermal fibroblasts (HDFs) and results showed that USC-sEVs could rejuvenate senescent fibroblasts by reversing the aging phenotypes of senescent HDFs and efficiently reducing the secretion of SASP after they activated the Sirt1 pathway. Therefore, USC-sEVs are efficient for enhancing wound healing in aged mice by ameliorating cellular senescence.

组织中的慢性皮肤伤口的再生仍然是再生医学中的关键挑战，因为衰老细胞的积累和伤口部位“衰老相关分泌表型”（SASP）的分泌增加。近来，一些研究报道，源自干细胞的小细胞外囊泡（sEVs）可以减轻细胞衰老，并且具有极低的肿瘤发生和免疫应答风险。正如我们先前的研究表明，尿液干细胞（USCs）可以轻松，无创地获得，而USCs（sucs-sEVs）衍生的sEVs具有再生组织损伤的能力，使用USC-sEVs可以增强老年人的慢性皮肤伤口愈合组织可能是一种可行且有效的策略。因此，在这项研究中 收集USC-sEV并先将其加载到人脱细胞羊膜（HAAM）中，以便在将USC-sEV植入老年小鼠的慢性皮肤伤口中之前在伤口部位进行控制释放和定位。体内结果表明，HAAM中的USC-sEV可通过改善细胞衰老和减少老年皮肤伤口中SASP的分泌来有效地促进伤口愈合。为了阐明其机理，USC-sEVs用于体外培养人皮肤成纤维细胞（HDFs），结果表明USC-sEVs可以通过逆转衰老的HDFs的衰老表型并活化SASP的分泌而有效地减少衰老的成纤维细胞。 Sirt1途径。因此，USC-sEV可通过改善细胞衰老来有效增强衰老小鼠的伤口愈合。