Laboratory of Fluorescence Dynamics, Biomedical Engineering Department, University of California, Irvine, CA 92697, USA.
Proc Natl Acad Sci U S A. 2011 Aug 16;108(33):13582-7. doi: 10.1073/pnas.1108161108. Epub 2011 Aug 1.
We describe a label-free imaging method to monitor stem-cell metabolism that discriminates different states of stem cells as they differentiate in living tissues. In this method we use intrinsic fluorescence biomarkers and the phasor approach to fluorescence lifetime imaging microscopy in conjunction with image segmentation, which we use to introduce the concept of the cell phasor. In live tissues we are able to identify intrinsic fluorophores, such as collagen, retinol, retinoic acid, porphyrin, flavins, and free and bound NADH. We have exploited the cell phasor approach to detect a trend in metabolite concentrations along the main axis of the Caenorhabditis elegans germ line. This trend is consistent with known changes in metabolic states during differentiation. The cell phasor approach to lifetime imaging provides a label-free, fit-free, and sensitive method to identify different metabolic states of cells during differentiation, to sense small changes in the redox state of cells, and may identify symmetric and asymmetric divisions and predict cell fate. Our method is a promising noninvasive optical tool for monitoring metabolic pathways during differentiation or disease progression, and for cell sorting in unlabeled tissues.
我们描述了一种无标记的成像方法，用于监测干细胞代谢，以区分干细胞在活组织中分化时的不同状态。在这种方法中，我们使用固有荧光生物标志物和荧光寿命成像显微镜的相子方法结合图像分割，引入了细胞相子的概念。在活组织中，我们能够识别内在的荧光团，如胶原蛋白、视黄醇、视黄酸、卟啉、黄素和游离态及结合态 NADH。我们利用细胞相子方法来检测秀丽隐杆线虫生殖系主轴上代谢物浓度的趋势。这一趋势与分化过程中代谢状态的已知变化一致。寿命成像的细胞相子方法提供了一种无标记、无拟合、敏感的方法，可以识别分化过程中细胞的不同代谢状态，感知细胞氧化还原状态的微小变化，并可能识别对称和不对称分裂，预测细胞命运。我们的方法是一种很有前途的非侵入性光学工具，可用于监测分化或疾病进展过程中的代谢途径，以及未标记组织中的细胞分选。
