Urine-derived stem cells (USCs) are a valuable stem cell source for tissue engineering because they can be harvested non-invasively. Small intestine submucosa (SIS) has been used as scaffolds for soft tissue repair in the clinic. However, the feasibility and efficacy of a combination of USCs and SIS for skin wound healing has not been reported. In this study, we created a tissue-engineered skin graft, termed the SIS+USC composite, and hypothesized that hypoxic preconditioning would improve its wound healing potential. USCs were seeded on SIS membranes to fabricate the SIS+USC composites, which were then cultured in normoxia (21% O2) or preconditioned in hypoxia (1% O2) for 24 h, respectively. The viability and morphology of USCs, the expression of genes related to wound angiogenesis and reepithelialization, and the secretion of growth factors were determined in vitro. The wound healing ability of the SIS+USC composites was evaluated in a mouse full-thickness skin wound model. USCs showed good cell viability and morphology in both normoxia and hypoxic preconditioning groups. In vitro, hypoxic preconditioning enhanced not only the expression of genes related to wound angiogenesis (VEGF and Ang-2) and reepithelialization (bFGF and EGF) but also the secretion of growth factors (VEGF, EGF, and bFGF). In vivo, hypoxic preconditioning significantly improved the wound healing potential of the SIS+USC composites. It enhanced wound angiogenesis at the early stage of wound healing, promoted reepithelialization, and improved the deposition and remodeling of collagen fibers at the late stage of wound healing. Taken together, this study shows that hypoxic preconditioning provides an easy and efficient strategy to enhance the wound healing potential of the SIS+USC composite.

中文翻译：

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人尿源性干细胞负载小肠黏膜下层的缺氧预处理可增强伤口愈合潜力。

尿源性干细胞 (USC) 是组织工程的宝贵干细胞来源，因为它们可以非侵入性地采集。小肠黏膜下层 (SIS) 已在临床用作软组织修复的支架。然而，USCs 和 SIS 联合用于皮肤伤口愈合的可行性和有效性尚未见报道。在这项研究中，我们创建了一种组织工程皮肤移植物，称为 SIS+USC 复合材料，并假设缺氧预处理会提高其伤口愈合潜力。将 USC 接种在 SIS 膜上以制备 SIS+USC 复合材料，然后分别在常氧（21% O2）中培养或在缺氧（1% O2）中预处理 24 小时。USCs的活力和形态，与伤口血管生成和再上皮化相关的基因的表达，并在体外测定生长因子的分泌。在小鼠全层皮肤伤口模型中评估了 SIS+USC 复合材料的伤口愈合能力。USC 在常氧和缺氧预处理组中均显示出良好的细胞活力和形态。在体外，低氧预处理不仅增强了与伤口血管生成（VEGF 和 Ang-2）和上皮再形成（bFGF 和 EGF）相关的基因的表达，还增强了生长因子（VEGF、EGF 和 bFGF）的分泌。在体内，低氧预处理显着提高了 SIS+USC 复合材料的伤口愈合潜力。它在伤口愈合早期增强了伤口血管生成，促进了上皮再生，改善了伤口愈合后期胶原纤维的沉积和重塑。综合起来，