BACKGROUND Exosome therapy shows potential for cardiac repair after injury. However, intrinsic challenges such as short half-life and lack of clear targets hinder the clinical feasibility. Here, we report a noninvasive and repeatable method for exosome delivery through inhalation after myocardial infarction (MI), which we called stem cell-derived exosome nebulization therapy (SCENT). METHODS Stem cell-derived exosomes were characterized for size distribution and surface markers. C57BL/6 mice with MI model received exosome inhalation treatment through a nebulizer for 7 consecutive days. Echocardiographies were performed to monitor cardiac function after SCENT, and histological analysis helped with the investigation of myocardial repair. Single-cell RNA sequencing of the whole heart was performed to explore the mechanism of action by SCENT. Last, the feasibility, efficacy, and general safety of SCENT were demonstrated in a swine model of MI, facilitated by 3-dimensional cardiac magnetic resonance imaging. RESULTS Recruitment of exosomes to the ischemic heart after SCENT was detected by ex vivo IVIS imaging and fluorescence microscopy. In a mouse model of MI, SCENT ameliorated cardiac repair by improving left ventricular function, reducing fibrotic tissue, and promoting cardiomyocyte proliferation. Mechanistic studies using single-cell RNA sequencing of mouse heart after SCENT revealed a downregulation of Cd36 in endothelial cells (ECs). In an EC-Cd36fl/- conditional knockout mouse model, the inhibition of CD36, a fatty acid transporter in ECs, led to a compensatory increase in glucose utilization in the heart and higher ATP generation, which enhanced cardiac contractility. In pigs, cardiac magnetic resonance imaging showed an enhanced ejection fraction (Δ=11.66±5.12%) and fractional shortening (Δ=5.72±2.29%) at day 28 after MI by SCENT treatment compared with controls, along with reduced infarct size and thickened ventricular wall. CONCLUSIONS In both rodent and swine models, our data proved the feasibility, efficacy, and general safety of SCENT treatment against acute MI injury, laying the groundwork for clinical investigation. Moreover, the EC-Cd36fl/- mouse model provides the first in vivo evidence showing that conditional EC-CD36 knockout can ameliorate cardiac injury. Our study introduces a noninvasive treatment option for heart disease and identifies new potential therapeutic targets.

中文翻译：

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可吸入干细胞外泌体促进心肌梗塞后的心脏修复。


背景技术外泌体疗法显示出损伤后心脏修复的潜力。然而，半衰期短和缺乏明确靶点等内在挑战阻碍了临床可行性。在这里，我们报告了一种在心肌梗塞（MI）后通过吸入进行外泌体递送的无创且可重复的方法，我们将其称为干细胞衍生的外泌体雾化疗法（SCENT）。方法对干细胞衍生的外泌体进行尺寸分布和表面标记物的表征。 MI模型C57BL/6小鼠通过雾化器连续7天接受外泌体吸入治疗。 SCENT 后进行超声心动图监测心脏功能，组织学分析有助于心肌修复的研究。对整个心脏进行单细胞 RNA 测序，以探索 SCENT 的作用机制。最后，通过 3 维心脏磁共振成像，在 MI 猪模型中证明了 SCENT 的可行性、有效性和总体安全性。结果 通过离体 IVIS 成像和荧光显微镜检测 SCENT 后外泌体向缺血心脏的募集。在 MI 小鼠模型中，SCENT 通过改善左心室功能、减少纤维化组织和促进心肌细胞增殖来改善心脏修复。 SCENT 后使用小鼠心脏单细胞 RNA 测序进行的机制研究揭示了内皮细胞 (EC) 中 Cd36 的下调。在 EC-Cd36fl/- 条件敲除小鼠模型中，抑制 EC 中的脂肪酸转运蛋白 CD36 导致心脏中葡萄糖利用率的代偿性增加和更高的 ATP 生成，从而增强心肌收缩力。在猪中，心脏磁共振成像显示射血分数增强（Δ=11.66±5.与对照组相比，MI 后第 28 天 SCENT 治疗后缩短分数 (Δ=5.72±2.29%)，并且梗塞面积减小，心室壁增厚。结论 在啮齿动物和猪模型中，我们的数据证明了 SCENT 治疗急性心肌梗死损伤的可行性、有效性和总体安全性，为临床研究奠定了基础。此外，EC-Cd36fl/-小鼠模型提供了第一个体内证据，表明条件性EC-CD36敲除可以改善心脏损伤。我们的研究引入了心脏病的无创治疗方案，并确定了新的潜在治疗靶点。