Department of Clinical Laboratory, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China (mainland).
Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China (mainland).
Med Sci Monit. 2018 Jun 29;24:4481-4488. doi: 10.12659/MSM.908567.
BACKGROUND Serum biomarkers are associated with eye diseases, which results in the need for cryopreservation of serum samples. However, the effect on serum biomarker levels of repeatedly freezing and thawing remains poorly understood. The aim of this study was to evaluate the effects of repeated freeze-thaw on the serum levels of the protein, complement C3c (C3c), the micromolecule, uric acid (UA), and the enzyme, angiotensin-converting enzyme (ACE). MATERIAL AND METHODS Serum samples were obtained from 50 patients who attended an ophthalmic outpatient department. Following baseline measurements, the serum samples from each subject were divided into aliquots and stored at -80°C for further analysis, following between one to six freeze-thaw cycles. The serum levels of C3c, UA, and ACE were measured immediately after the stored serum samples were thawed. RESULTS The serum level of C3c was significantly changed after the first freeze-thaw cycle (p<0.05), and a significant alteration in serum ACE levels occurred after the third freeze-thaw cycle (p<0.05). The serum UA level remained unchanged after all freeze-thaw cycles. Repeated freeze-thaw cycles significantly increased the serum levels of C3c and decreased the serum levels of ACE. The serum levels of C3c, UA, and ACE, respectively were significantly correlated (p<0.001), while the correlation coefficient for C3c and UA were improved when compared with ACE. CONCLUSIONS Repeated freeze-thaw can have variable effects on the serum levels of biomarkers, C3c, UA and ACE, which supports the need for quality control of cryopreserved serum for biomarker evaluation.
血清生物标志物与眼部疾病相关，这导致需要对血清样本进行冷冻保存。然而，反复冻融对血清生物标志物水平的影响仍知之甚少。本研究旨在评估反复冻融对蛋白 C3c（C3c）、小分子尿酸（UA）和酶血管紧张素转化酶（ACE）的血清水平的影响。
从参加眼科门诊的 50 名患者中获得血清样本。在基线测量后，将每个受试者的血清样本分成等分试样，并在 -80°C 下储存以备进一步分析，在一到六个冻融循环之间。在储存的血清样本解冻后立即测量 C3c、UA 和 ACE 的血清水平。
第一次冻融循环后 C3c 的血清水平明显改变（p<0.05），第三次冻融循环后 ACE 水平发生明显改变（p<0.05）。所有冻融循环后 UA 血清水平保持不变。反复冻融循环显著增加 C3c 的血清水平，降低 ACE 的血清水平。C3c、UA 和 ACE 的血清水平分别呈显著相关（p<0.001），而与 ACE 相比，C3c 和 UA 的相关系数得到改善。
反复冻融对 C3c、UA 和 ACE 等生物标志物的血清水平有不同的影响，这支持了对用于生物标志物评估的冷冻保存血清进行质量控制的需要。
