胰腺癌的早期诊断对于患者生存率的提高具有重要意义，但目前临床上胰腺癌的早期诊断方法仍不理想。研究表明，磷脂酰肌醇聚糖-1（GPC1）在胰腺肿瘤细胞来源外泌体表面高度表达，GPC1阳性外泌体是一种高灵敏度高特异性的胰腺癌早期诊断生物标志物。但由于缺少灵敏、便捷、准确的GPC1阳性外泌体定量检测方法，其临床应用受到了较大限制。本课题首次提出了将外泌体转化为可扩增检测的核酸信号分子的定量分析策略，拟利用不同序列核酸分子标记的抗体探针与免疫磁珠表面富集的外泌体进行特异性结合，从而实现外泌体信号向核酸信号的转化，采用级联核酸侵入反应对不同核酸信号分子同时进行扩增检测，建立一种基于核酸扩增的高灵敏度、低成本且无需昂贵设备的GPC1阳性外泌体检测新方法。通过将该方法用于临床血清样品的检测，评价其对胰腺癌早期诊断的价值，以期为临床提供一种胰腺癌早期筛查的新方法。

Early diagnosis of pancreatic cancer is imperative to improve the survival rate of patients, however clinical methods for early diagnosis of pancreatic cancer still remains unsatisfying. Studies have shown that glypican-1 (GPC1) specifically enrich on cancer-cell-derived exosomes and GPC1+ exosomes are a highly sensitive and specific biomarker for pancreatic cancer. Nonetheless, the clinical application of GPC1+ exosomes is limited due to a lack of sensitive, convenient and accurate GPC1+ exosomes quantification method. In this study, a novel quantitative detection strategy is proposed, in which the detection of exosomes is transformed into amplifiable oligonucleotide signal molecules. The transformation is achieved by marking immunomagnetic beads enriched exosomes by antibody probes labeled with different sequence oligonucleotide. The oligonucleotide specific to different exosomes are then amplified and detected by a cascade invasion reaction, simultaneously. In this way, a highly sensitive and low cost novel quantification method for of GPC1+ exosomes will be established based on oligonucleotide amplification. The proposed method will be further validated by clinical samples and applied to early diagnosis of pancreatic cancer.