Anatomical Institute José Izquierdo, Faculty of Medicine, Central University of Venezuela, 1050 Caracas, Venezuela.
Acta Histochem. 2011 May;113(3):363-8. doi: 10.1016/j.acthis.2010.01.008. Epub 2010 Feb 6.
When cultured cells are treated with fluorescent organelle probes or photosensitizer agents, a characteristic redistribution of fluorescence in cell structures occurs frequently after light irradiation. It is currently assumed that such changes, referred to as relocalizations of the fluorescent compounds, represent an important aspect of the photodynamic process, which is based on the excitation of photosensitizers by light in the presence of oxygen. As cell damage and death result from the oxidative stress induced by photodynamic treatments, we have studied here the redistribution of acridine orange (AO) and 3,3'-dimethyl-oxacarbocyanine (DiOC(1)(3)) fluorescence after incubation of HeLa cell cultures with these compounds followed by blue light irradiation to achieve lethal effects. The relocalization of dyes from their original labeling sites (AO: lysosomes, DiOC(1)(3): mitochondria) to nucleic acid-containing structures (cytoplasm, nuclei and nucleoli) appeared clearly associated with cell death. Therefore, the relocalization phenomenon simply reflects fluorescence changes due to the different affinity of these dyes for living and damaged or dead cells. As fluorescent probes are often photosensitizers, prolonged light exposures using fluorescence microscopy will produce lethal photodynamic effects with relocalization of the fluorescent signal and changes in the cell morphology.
当培养细胞用荧光细胞器探针或光敏剂处理时，在光照射后，细胞结构中的荧光常常会发生特征性的重新分布。目前认为，这种被称为荧光化合物重定位的变化，代表了光动力过程的一个重要方面，该过程基于在氧气存在下光敏剂被光激发。由于光动力处理引起的氧化应激导致细胞损伤和死亡，我们在此研究了吖啶橙（AO）和 3,3'-二甲基氧杂羰花青（DiOC(1)(3)）在与这些化合物孵育后，用蓝光照射实现致死效应时的荧光重新分布。染料从其原始标记位置（AO：溶酶体，DiOC(1)(3)：线粒体）到含有核酸的结构（细胞质、细胞核和核仁）的重新定位，与细胞死亡明显相关。因此，重定位现象仅仅反映了由于这些染料对活细胞和受损或死亡细胞的不同亲和力而导致的荧光变化。由于荧光探针通常也是光敏剂，因此使用荧光显微镜进行长时间的光照会产生致死的光动力效应，同时荧光信号发生重定位和细胞形态发生变化。
