Grude Olaug, Hammiche Azzedine, Pollock Hubert, Bentley Adam J, Walsh Michael J, Martin Francis L, Fullwood Nigel J
Biomedical Sciences, Department of Biological Sciences, Lancaster University, Lancaster, U.K., and Department of Physics, Lancaster University, Lancaster, UK.
J Microsc. 2007 Dec;228(Pt 3):366-72. doi: 10.1111/j.1365-2818.2007.01853.x.
The identification of stem cells in adult tissue is a challenging problem in biomedicine. Currently, stem cells are identified by individual epitopes, which are generally tissue specific. The discovery of a stem-cell marker common to other adult tissue types could open avenues in the development of therapeutic stem-cell strategies. We report the use of the novel technique of Fourier transform infrared near-field photothermal microspectroscopy (FTIR-PTMS) for the characterization of stem cells, transit amplifying (TA) cells and terminally differentiated (TD) cells in the corneal epithelium. Principal component analysis (PCA) data demonstrate excellent discrimination of cell type by spectra. PCA in combination with linear discriminant analysis (PCA-LDA) shows that FTIR-PTMS very effectively discriminates between the three cell populations. Statistically significant differences above the 99% confidence level between IR spectra from stem cells and TA cells suggest that nucleic acid conformational changes are an important component of the differences between spectral data from the two cell types. FTIR-PTMS is a new addition to existing spectroscopy methods based on the concept of interfacing a conventional FTIR spectrometer with an atomic force microscope equipped with a near-field thermal sensing probe. FTIR-PTMS spectroscopy currently has spatial resolution that is similar to that of diffraction-limited optical detection FTIR spectroscopy techniques, but as a near-field probing technique has considerable potential for further improvement. Our work also suggests that FTIR-PTMS is potentially more sensitive than synchrotron radiation FTIR spectroscopy for some applications. Microspectroscopy techniques like FTIR-PTMS provide information about the entire molecular composition of cells, in contrast to epitope recognition that only considers the presence or absence of individual molecules. Our results with FTIR-PTMS on corneal stem cells are promising for the potential development of an IR spectral fingerprint for stem cells.
在生物医学中，鉴定成体组织中的干细胞是一个具有挑战性的问题。目前，干细胞是通过个体表位来鉴定的，这些表位通常具有组织特异性。发现一种适用于其他成体组织类型的干细胞标志物，可能为治疗性干细胞策略的开发开辟道路。我们报告了使用傅里叶变换红外近场光热显微光谱技术（FTIR-PTMS）对角膜上皮中的干细胞、过渡扩增（TA）细胞和终末分化（TD）细胞进行表征。主成分分析（PCA）数据表明，通过光谱可以很好地区分细胞类型。PCA与线性判别分析（PCA-LDA）相结合表明，FTIR-PTMS能够非常有效地区分这三种细胞群体。干细胞和TA细胞的红外光谱在99%置信水平以上存在统计学显著差异，这表明核酸构象变化是这两种细胞类型光谱数据差异的重要组成部分。FTIR-PTMS是基于将传统傅里叶变换红外光谱仪与配备近场热传感探针的原子力显微镜相结合的概念而新增的现有光谱学方法。FTIR-PTMS光谱目前的空间分辨率与衍射极限光学检测傅里叶变换红外光谱技术相似，但作为一种近场探测技术，具有进一步改进的巨大潜力。我们的工作还表明，在某些应用中，FTIR-PTMS可能比同步辐射傅里叶变换红外光谱更灵敏。与仅考虑单个分子存在与否的表位识别不同，像FTIR-PTMS这样的显微光谱技术能够提供有关细胞整个分子组成信息。我们使用FTIR-PTMS对角膜干细胞的研究结果为开发干细胞的红外光谱指纹图谱带来了希望。
