Applied Optics and Biophotonics Laboratory, Department of Physics, Indian Institute of Technology Delhi, Delhi, India.
Department of Physics and Technology, UiT The Arctic Univ. of Norway, Tromsø, Norway.
Sci Rep. 2019 Mar 5;9(1):3564. doi: 10.1038/s41598-019-39523-5.
Semen quality assessed by sperm count and sperm cell characteristics such as morphology and motility, is considered to be the main determinant of men's reproductive health. Therefore, sperm cell selection is vital in assisted reproductive technology (ART) used for the treatment of infertility. Conventional bright field optical microscopy is widely utilized for the imaging and selection of sperm cells based on the qualitative analysis by experienced clinicians. In this study, we report the development of a highly sensitive quantitative phase microscopy (QPM) using partially spatially coherent light source, which is a label-free, non-invasive and high-resolution technique to quantify various biophysical parameters. The partial spatial coherence nature of light source provides a significant improvement in spatial phase sensitivity and hence reconstruction of the phase of the entire sperm cell is demonstrated, which was otherwise not possible using highly spatially coherent light source. High sensitivity of the system enables quantitative phase imaging of the specimens having very low refractive index contrast with respect to the medium like tail of the sperm cells. Further, it also benefits with accurate quantification of 3D-morphological parameters of sperm cells which might be helpful in the infertility treatment. The quantitative analysis of more than 2500 sperm cells under hydrogen peroxide (HO) induced oxidative stress condition is demonstrated. It is further correlated with motility of sperm cell to study the effect of oxidative stress on healthy sperm cells. The results exhibit a decrease in the maximum phase values of the sperm head as well as decrease in the sperm cell's motility with increasing oxidative stress, i.e., HO concentration. Various morphological and texture parameters were extracted from the phase maps and subsequently support vector machine (SVM) based machine learning algorithm is employed for the classification of the control and the stressed sperms cells. The algorithm achieves an area under the receiver operator characteristic (ROC) curve of 89.93% based on the all morphological and texture parameters with a sensitivity of 91.18%. The proposed approach can be implemented for live sperm cells selection in ART procedure for the treatment of infertility.
精液质量通过精子计数和精子形态和运动等细胞特征来评估，被认为是男性生殖健康的主要决定因素。因此，精子细胞的选择在用于治疗不孕不育的辅助生殖技术（ART）中至关重要。传统的明场光学显微镜广泛用于基于经验丰富的临床医生的定性分析对精子细胞进行成像和选择。在这项研究中，我们报告了一种使用部分空间相干光源的高灵敏度定量相显微镜（QPM）的开发，该技术是一种无标记、非侵入性和高分辨率的技术，可定量测量各种生物物理参数。光源的部分空间相干性质显著提高了空间相位灵敏度，从而实现了整个精子细胞的相位重建，这在使用高度空间相干光源时是不可能的。该系统的高灵敏度使得能够对相对于介质（如精子尾部）具有非常低折射率对比度的标本进行定量相成像。此外，它还可以准确地量化精子细胞的 3D 形态参数，这可能有助于不孕不育的治疗。在过氧化氢（HO）诱导的氧化应激条件下，对超过 2500 个精子细胞进行了定量分析。进一步将其与精子细胞的运动能力相关联，以研究氧化应激对健康精子细胞的影响。结果表明，随着氧化应激（即 HO 浓度）的增加，精子头部的最大相位值以及精子细胞的运动能力降低。从相位图中提取了各种形态和纹理参数，随后采用基于支持向量机（SVM）的机器学习算法对对照和应激精子细胞进行分类。该算法基于所有形态和纹理参数实现了接收者操作特征（ROC）曲线下面积为 89.93%的分类，灵敏度为 91.18%。该方法可用于 ART 程序中的活精子细胞选择，以治疗不孕不育。
