Zarnescu Livia, Leung Michael C, Abeyta Michael, Sudkamp Helge, Baer Thomas, Behr Barry, Ellerbee Audrey K
Stanford University, Department of Bioengineering, 443 Via Ortega, Stanford, California 94305, United States.
Stanford University, E.L. Ginzton Laboratory and Department of Electrical Engineering, 450 Serra Mall, Stanford, California 94305, United States.
J Biomed Opt. 2015 Sep;20(9):096004. doi: 10.1117/1.JBO.20.9.096004.
Vitrification is an increasingly popular method of embryo cryopreservation that is used in assisted reproductive technology. Although vitrification has high post-thaw survival rates compared to other freezing techniques, its long-term effects on embryo development are still poorly understood. We demonstrate an application of full-field optical coherence tomography (FF-OCT) to visualize the effects of vitrification on live single-cell (2 pronuclear) mouse embryos without harmful labels. Using FF-OCT, we observed that vitrification causes a significant increase in the aggregation of structures within the embryo cytoplasm, consistent with reports in literature based on fluorescence techniques. We quantify the degree of aggregation with an objective metric, the cytoplasmic aggregation (CA) score, and observe a high degree of correlation between the CA scores of FF-OCT images of embryos and of fluorescence images of their mitochondria. Our results indicate that FF-OCT shows promise as a label-free assessment of the effects of vitrification on embryo mitochondria distribution. The CA score provides a quantitative metric to describe the degree to which embryos have been affected by vitrification and could aid clinicians in selecting embryos for transfer.
玻璃化冷冻是辅助生殖技术中一种越来越流行的胚胎冷冻保存方法。尽管与其他冷冻技术相比，玻璃化冷冻具有较高的解冻后存活率，但其对胚胎发育的长期影响仍知之甚少。我们展示了全视野光学相干断层扫描（FF-OCT）在可视化玻璃化冷冻对活的单细胞（双原核）小鼠胚胎的影响方面的应用，且无需使用有害标记物。使用FF-OCT，我们观察到玻璃化冷冻会导致胚胎细胞质内结构聚集显著增加，这与基于荧光技术的文献报道一致。我们用一个客观指标——细胞质聚集（CA）评分来量化聚集程度，并观察到胚胎的FF-OCT图像的CA评分与其线粒体荧光图像的CA评分之间具有高度相关性。我们的结果表明，FF-OCT有望作为一种无标记方法来评估玻璃化冷冻对胚胎线粒体分布的影响。CA评分为描述胚胎受玻璃化冷冻影响的程度提供了一个定量指标，并可帮助临床医生选择用于移植的胚胎。
