Huang Yanqin, Mu Jiayi, Qi Lina, Ge Weiting, Fang Xuefeng, Song Yongmao, Yuan Ying, Zheng Shu
Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Key Laboratory of Molecular Biology in Medical Sciences, Zhejiang Province), The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang Province, P.R. China.
Department of Medical Oncology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, P.R. China.
Clin Chem Lab Med. 2020 Mar 28;58(9):1451-1459. doi: 10.1515/cclm-2020-0078. Print 2020 Aug 27.
The objective of this study was to determine the features of fragment length for circulating cell-free DNA (cfDNA) from plasma and serum samples.
Plasma and serum samples from different sources were randomly collected. Circulating cfDNA was extracted and purified by a precipitation-enriched and spin-column-based kit. The concentration of the purified DNA was immediately measured by a highly sensitive dsDNA quantitative assay, and then the fragment length was analyzed by capillary electrophoresis. The abundance of a specific fragment was estimated by the area under curve (AUC) for the fragment peak in the capillary electrophoresis.
A total of 199 plasma and 117 serum samples were extracted and analyzed. The average yield of cfDNA from the serum samples (131.67 ng/mL) was significantly higher than that from the plasma samples (32.78 ng/mL, p < 0.001). The average abundance of the 20-400 bp fragments in plasma cfDNA (84.4%) was significantly higher than that of serum cfDNA (51.9%, p < 0.001). Fragment peaks in serum cfDNA always presented in regions around 190 bp, 430 bp, and 630 bp, but plasma cfDNA generally showed a sharp peak in the 165-190 bp region and a much lower peak in the 300<uni-2013;400 bp region. Large fragments in plasma cfDNA were longer than 1000 bp and peaked around the 3000<uni-2013;4000 bp region while the large fragments in serum cfDNA were always shorter and peaked around the 1000 bp region.
The fragment lengths of serum cfDNA and plasma cfDNA have very different features. Fragment size selection is suitable for plasma cfDNA but may not apply to serum cfDNA.
本研究的目的是确定来自血浆和血清样本的循环游离DNA（cfDNA）的片段长度特征。
随机收集不同来源的血浆和血清样本。采用沉淀富集和基于离心柱的试剂盒提取并纯化循环cfDNA。通过高灵敏度双链DNA定量测定法立即测量纯化后DNA的浓度，然后通过毛细管电泳分析片段长度。通过毛细管电泳中片段峰的曲线下面积（AUC）估计特定片段的丰度。
共提取并分析了199份血浆样本和117份血清样本。血清样本中cfDNA的平均产量（131.67 ng/mL）显著高于血浆样本（32.78 ng/mL，p < 0.001）。血浆cfDNA中20 - 400 bp片段的平均丰度（84.4%）显著高于血清cfDNA（51.9%，p < 0.001）。血清cfDNA中的片段峰总是出现在190 bp、430 bp和630 bp左右的区域，但血浆cfDNA通常在165 - 190 bp区域有一个尖锐峰，在300 - 400 bp区域有一个低得多的峰。血浆cfDNA中的大片段长度超过1000 bp，在3000 - 4000 bp区域达到峰值，而血清cfDNA中的大片段总是较短，在1000 bp区域达到峰值。
血清cfDNA和血浆cfDNA的片段长度具有非常不同的特征。片段大小选择适用于血浆cfDNA，但可能不适用于血清cfDNA。
