Horneffer Verena, Linz Norbert, Vogel Alfred
University of Lübeck, Institute of Biomedical Optics, Peter-Monnik Weg 4, D-23562 Lübeck, Germany.
J Biomed Opt. 2007 Sep-Oct;12(5):054016. doi: 10.1117/1.2799194.
Separation and transport of defined populations of living cells grown on a thin membrane can be achieved by laser microdissection (LMD) of the sample of interest, followed by a laser-induced forward transport process [laser pressure "catapulting" (LPC)] of the dissected cell cluster. We investigate the dynamics of LMD and LPC with focused and defocused UV-A laser pulses by means of time-resolved photography. Catapulting is driven by plasma formation when tightly focused pulses are used, and by confined thermal ablation at the bottom of the sample for defocused catapulting. With both modalities, the initial specimen velocity amounts to about 50 to 60 ms. Time-resolved photography of live cell catapulting reveals that in defocused catapulting, strong shear forces arise when the sample is accelerated out of the culture medium covering the cells. By contrast, pulses focused at the periphery of the specimen cause a fast rotational movement that minimizes the flow of culture medium parallel to the sample surface, and thus the resulting shear stresses. Therefore, the recultivation rate of catapulted cells is much higher when focused pulses are used. Compared to collateral damage by mechanical forces, side effects by heat and UV exposure of the cells play only a minor role.
通过对感兴趣的样本进行激光显微切割（LMD），然后对切割后的细胞团进行激光诱导正向传输过程[激光压力“弹射”（LPC）]，可以实现生长在薄膜上的特定活细胞群体的分离和运输。我们通过时间分辨摄影术，利用聚焦和散焦的UV-A激光脉冲研究了LMD和LPC的动力学。当使用紧聚焦脉冲时，弹射是由等离子体形成驱动的，而对于散焦弹射，是由样品底部的受限热烧蚀驱动的。在这两种模式下，初始标本速度约为50至60米/秒。活细胞弹射的时间分辨摄影显示，在散焦弹射过程中，当样品从覆盖细胞的培养基中加速出来时，会产生强大的剪切力。相比之下，聚焦在标本周边的脉冲会引起快速的旋转运动，从而使平行于样品表面的培养基流动最小化，进而使产生的剪切应力最小化。因此，使用聚焦脉冲时，弹射细胞的再培养率要高得多。与机械力造成的附带损伤相比，细胞受热和紫外线照射产生的副作用只起次要作用。
