Fadhel Muhannad N, Hysi Eno, Strohm Eric M, Kolios Michael C
Department of Physics, Ryerson University, Toronto, ON, Canada.
Institute for Biomedical Engineering, Science and Technology (iBEST), Toronto, ON, Canada.
J Biophotonics. 2019 Sep;12(9):e201800431. doi: 10.1002/jbio.201800431. Epub 2019 Jun 14.
Under stress, red blood cells (RBCs) undergo programmed cell death (eryptosis). One of the signaling molecules for eryptosis, sphingomyelinase (SMase), plays an important role in monitoring the efficacy of vascular targeted cancer therapy. The high optical absorption of erythrocytes coupled with the changes of eryptotic RBCs makes RBCs ideal targets for the photoacoustic (PA) detection and characterization of vascular treatments. In this work, experiments characterizing eryptosis were performed: PA detection of high frequencies (>100 MHz) that enabled analysis at the single-cell level and of low frequencies (21 MHz) that enabled analysis at the RBC ensemble level. Ultrasound spectral analysis was performed on control and SMase-treated RBCs. Spectral unmixing was applied to quantify methemoglobin production as a by-product of RBC death. Validation was performed using a blood gas analyzer and optical spectrometry. Our results indicate that PA radiofrequency spectra could be used to differentiate the biochemically induced morphological changes as RBCs lose their native biconcave shape, and release hemoglobin into the surroundings. Spectral unmixing revealed a 7% increase in methemoglobin content for SMase-treated samples due to the oxidative stress on the RBCs. These findings suggest that PA spectral analysis of RBC death can potentially serve as a biomarker of the efficacy of vascular targeted cancer therapies.
在应激状态下，红细胞（RBCs）会经历程序性细胞死亡（红细胞凋亡）。红细胞凋亡的信号分子之一，鞘磷脂酶（SMase），在监测血管靶向癌症治疗的疗效中起着重要作用。红细胞的高光学吸收以及凋亡红细胞的变化使红细胞成为光声（PA）检测和表征血管治疗的理想靶点。在这项工作中，进行了表征红细胞凋亡的实验：对高频（>100 MHz）进行光声检测，以实现单细胞水平的分析；对低频（21 MHz）进行光声检测，以实现红细胞整体水平的分析。对对照和经SMase处理的红细胞进行了超声光谱分析。应用光谱解混来量化作为红细胞死亡副产物的高铁血红蛋白的产生。使用血气分析仪和光学光谱法进行了验证。我们的结果表明，随着红细胞失去其天然的双凹形状并将血红蛋白释放到周围环境中，光声射频光谱可用于区分生化诱导的形态变化。光谱解混显示，由于红细胞受到氧化应激，经SMase处理的样品中高铁血红蛋白含量增加了7%。这些发现表明，红细胞死亡的光声光谱分析有可能作为血管靶向癌症治疗疗效的生物标志物。
