两种冰冻切片包埋剂在解吸电喷雾电离质谱成像分析检测中的性能比较

Performance Comparison of Two Cryosection Embedding Agents Used for Desorption Electrospray Ionization Mass Spectrometry Imaging

目的评估经羧甲基纤维素(carboxylmethyl cellulose,CMC)包埋、最佳切割温度(optimal cutting temperature,OCT)化合物包埋及OCT清洗处理后,对乳腺癌组织样本解吸电喷雾电离质谱成像分析(desorption electrospray ionization mass spectrometry imaging,DESI-MSI)的潜在影响。方法对同一乳腺癌肿瘤组织,采用直接新鲜冰冻、OCT包埋、CMC包埋、OCT包埋后PBS清洗样本切片并进行DESI-MSI实验。最大强度离子比值用于数据重现性检查,特征离子种类和信号强度用于比较处理方式的影响。结果新鲜冰冻样本连续切片DESI-MSI显示,质量与电荷之比(m/z)为281.25、309.28和279.23的3个离子在肿瘤区域信号检出强度最高,其两两比值变异系数分别为19.61%、20.74%和10.18%。与新鲜冰冻肿瘤组织相比,CMC包埋及OCT包埋后清洗样本检测出的特征离子种类基本无异,而OCT包埋样本检出数目不及新鲜冰冻样本的50%。就信号强度而言,相对新鲜冰冻肿瘤组织,CMC包埋后整体无明显差异,而OCT包埋清洗后大多数特征离子信号强度下降(P<0.05)。结论新鲜冰冻组织和CMC包埋处理样本可用于DESI-MSI常规分析,OCT包埋组织无论是否经PBS清洗,其分析可行性均受到影响。对于体积小、易碎或由于其他问题而需固定的组织切片样本,推荐使用CMC包埋。

Objective To evaluate the potential effect of embedding with carboxylmethyl cellulose(CMC)and embedding with optimal cutting temperature(OCT)compound followed by washing with PBS(OCT-W)on the analysis of breast cancer tissue samples with desorption electrospray ionization mass spectrometry imaging(DESI-MSI).Methods DESI-MSI of fresh frozen(FF)tissue samples,OCT-embedded samples,CMC-embedded samples,and OCT-W samples from the same breast cancer tumor tissue were performed.The ratio of maximum abundance ion was used to assess the reproducibility of DESI-MSI analysis.In addition,the effects of the treatment of each group were examined by comparing the characteristic ion species and the ion signal intensity detected by DESI-MSI.Results DESI-MSI of continuous sections of FF samples showed that the coefficient of variation(CV)of the pair-to-pair ratios of m/z 281.25,m/z 309.28 and m/z 279.23 ions,the three ions with the highest intensity in the tumor region,were 19.61%,20.74%and 10.18%,respectively.The characteristic ion species detected by DESI-MSI of CMC embedded tissue and the OCT-W tissue were almost the same,compared with those of the FF tumor tissue.However,ion species detected in OCT embedded samples were less than 50%of the FF samples.In terms of ion signal intensity,the CMC embedded tissue was not affected overall,while the signal of most of the characteristic ions of the OCT-W group showed decreased intensity(P<0.05).Conclusion FF tissue sections and CMC-embedded samples can be used for DESI-MSI routine analysis.OCT embedding affects the feasibility of sample analysis whether or not the sample undergoes washing with PBS.CMC embedding agent is recommended if the tissue sections need to be fixated and supported due to small sample size,fragility,or other problems.