Lehrstuhl für Experimentelle Genetik, Technische Universität München , 85350 Freising-Weihenstephan, Germany.
German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany.
J Proteome Res. 2018 Jan 5;17(1):203-211. doi: 10.1021/acs.jproteome.7b00518. Epub 2017 Nov 28.
Prolonged storage of biospecimen can lead to artificially altered metabolite concentrations and thus bias data analysis in metabolomics experiments. To elucidate the potential impact of long-term storage on the metabolite profile, a pooled human plasma sample was aliquoted and stored at -80 °C. During a time period of five years, 1012 of the aliquots were measured with the Biocrates AbsoluteIDQ p180 targeted-metabolomics assay at 193 time points. Modeling the concentration courses over time revealed that 55 out of 111 metabolites remained stable. The statistically significantly changed metabolites showed on average an increase or decrease of +13.7% or -14.5%, respectively. In detail, increased concentration levels were observed for amino acids (mean: + 15.4%), the sum of hexoses (+7.9%), butyrylcarnitine (+9.4%), and some phospholipids mostly with chain lengths exceeding 40 carbon atoms (mean: +18.0%). Lipids tended to exhibit decreased concentration levels with the following mean concentration changes: acylcarnitines, -12.1%; lysophosphatidylcholines, -15.1%; diacyl-phosphatidylcholines, -17.0%; acyl-alkyl-phosphatidylcholines, -13.3%; sphingomyelins, -14.8%. We conclude that storage of plasma samples at -80 °C for up to five years can lead to altered concentration levels of amino acids, acylcarnitines, glycerophospholipids, sphingomyelins, and the sum of hexoses. These alterations must be considered when analyzing metabolomics data from long-term epidemiological studies.
生物标本的长时间储存可能导致代谢物浓度人为改变，从而影响代谢组学实验中的数据分析。为了阐明长期储存对代谢物谱的潜在影响，将一份混合人血浆样本等分并储存在-80°C。在五年的时间内，1012 份等分样本通过 Biocrates AbsoluteIDQ p180 靶向代谢组学测定法在 193 个时间点进行了测量。对随时间推移的浓度变化进行建模表明，111 种代谢物中有 55 种保持稳定。统计学上发生变化的代谢物平均分别增加或减少了+13.7%或-14.5%。具体而言，观察到氨基酸（平均：+15.4%）、己糖总和（+7.9%）、丁酰肉碱（+9.4%）和一些长链超过 40 个碳原子的磷脂（平均：+18.0%）的浓度水平升高。脂质倾向于表现出浓度降低，以下是平均浓度变化：酰基辅酶 A，-12.1%；溶血磷脂酰胆碱，-15.1%；二酰基磷脂酰胆碱，-17.0%；酰基-烷基磷脂酰胆碱，-13.3%；鞘磷脂，-14.8%。我们得出结论，将血浆样本储存在-80°C 长达五年可能导致氨基酸、酰基辅酶 A、甘油磷脂、鞘磷脂和己糖总和的浓度水平发生改变。在分析来自长期流行病学研究的代谢组学数据时，必须考虑这些变化。
