Infrared and Raman Microspectroscopic Studies of Individual Human Cells

Spectral cytology, the diagnosis of disease based on objective physical measurements on individual cells and subsequent computer-based algorithmic interpretation, promises to provide faster and more reliable results than classical cytology. The measurements described in this review are based on well-established vibrational microspectroscopic techniques, which provide a snapshot of the biochemical composition of a cell, or parts thereof. The spectral data are subsequently diagnosed by unsupervised and supervised methods of multivariate analysis. More than any other recent attempts to improve on cytology, these spectral methods exhibit exquisite sensitivity toward small changes in cellular conditions. In fact, these cellular conditions, for example, fixation or proliferation state, have to be controlled very carefully to eliminate spurious effects. This chapter provides the ground work for later applications of this methodology in medical diagnostics. Furthermore, the application of novel research tools, such as confocal Raman microscopy, followed by cluster analysis of the hyperspectral data sets, and their relevance to research in cellular biology are described. Keywords: spectral cytology; infrared microspectroscopy; confocal Raman microspectroscopy; multivariate statistical analysis; hyperspectral analysis; principal component analysis; urine cytology; HeLa cells; buccal cells; cervical cells