脂肪间充质干细胞在继发性淋巴水肿发病机制中的作用研究

Lymphedema is characterized by regional swelling, due to excess accumulation of lymph fluid and fat in tissue, which will cause severe morbidity. A large number of people are suffering from lymphedema, which is a problem for clinical treatment. Local abnormal fat deposition and fibrosis are the important pathological changes, but the mechanism is unknown. Animal experiments showed that the number of fat cells in lymphoid edema tissue increased, but the origin and mechanism of increased fat cells were unclear. ADSCs(adipose-derived stem cells) is the stem cells presented in adipose tissue, which can gradually differentiate into mature adipocytes in the regulation of tissue microenvironment, and the ADSCs are the main source of increased fat cells in adult tissue and organ. ADSCs primarily exert their physiological functions through secreted exosomes and other membrane vesicles. Our previous study found that ADSCs derived from secondary lymphedema patient diseased tissue has stronger adipogenic differentiation ability than normal tissue-derived ADSCs; and the exosomes derived from diseased tissue ADSCs also has contained higher pro-fibrotic miRs than that derived from normal tissue ADSCs. This project aims to compare the adipogenic differentiation ability and transcripts differences of ADSCs derived from normal and diseased tissue of lymphatic edema patients, to explain the molecular mechanisms of lymphedema fat deposition; to further study the role in tissue fibrosis and signaling pathway of the exosomes derived from lymphedema tissue ADSCs; and to lay the foundation of revealing lymphedema pathophysiology, also provide new ideas for lymphedema treatment.

淋巴水肿罹患人数庞大，是临床治疗难题。局部脂肪异常沉积、组织纤维化是其重要病理改变，机制不明。动物实验发现淋巴水肿组织中脂肪细胞数目增多，但增加的脂肪细胞来源及调控机制不清。脂肪间充质干细胞(ADSCs)在组织微环境调控下能分化为成熟脂肪细胞，是组织器官中脂肪细胞数目异常增加的主要来源。ADSCs主要通过外泌小体(exosome)等膜性囊泡形式发挥生理功能。我们前期研究发现继发淋巴水肿患者病变组织来源ADSCs的成脂分化明显强于其正常组织来源ADSCs;其分泌的exosome中多种促纤维化miRs含量亦高于正常ADSCs。本项目旨在比较淋巴水肿患者正常及病变组织ADSCs成脂分化能力及其转录本差异，阐述淋巴水肿脂肪沉积的分子机制;并进一步研究继发性淋巴水肿组织中hADSCs来源exosome在纤维化中的作用及相应信号通路;为揭示淋巴水肿病理生理机制奠定基础，亦为淋巴水肿的治疗提供新的思路。

继发性淋巴水肿是恶性肿瘤患者的常见症状，但保守治疗不能提供持久的缓解，因为它们不能解决潜在的病态脂肪堆积问题。本研究旨在阐明淋巴水肿脂肪组织异常成脂分化的分子机制。我们比较了10例淋巴水肿患者抽脂后的脂肪源性间充质干细胞（ADSCs）与同一患者正常上腹脂肪源性间充质干细胞的增殖和成脂潜能。通过转录组分析，确定两种ADSCs之间的差异。细胞周期依赖性激酶1（CDK1）抑制剂用于治疗淋巴水肿脂肪组织中的异常ADSCs。此外我们对来自3个供体的24358个培养的人ADSCs进行了大规模的单细胞转录组测序。我们提供了一个高质量的数据集，用于分析比较培养的ADSCs的种群内异质性，并在单细胞分辨率上提供谱系模型。我们的结果表明，两种ADSCs在功能和转录组上存在显著差异。其中上调的基因主要参与细胞增殖和分裂，下调的基因主要与免疫应答、炎症、成骨和成肌分化有关。此外，我们发现淋巴水肿脂肪组织中的ADSCs过度增殖和脂肪生成在CDK1抑制剂的作用下能恢复到正常表型。来自淋巴水肿脂肪组织的ADSCs具有较高的免疫抑制作用，与免疫抑制相关的细胞因子显著上调。淋巴水肿相关ADSCs具有更快速的增殖和更高的成脂分化能力。CDK1可能是这些细胞增殖和成脂分化的关键驱动因素，这可能解释了在继发性淋巴水肿中广泛观察到的脂肪组织积累现象，来自淋巴水肿脂肪组织的ADSCs表现出免疫调节功能障碍，免疫调节可能在淋巴水肿的发病机制中起重要作用。