Confocal Raman spectroscopy and multivariate data analysis for evaluation of spermatozoa with normal and abnormal morphology. A feasibility study

This paper investigates a feasibility of using confocal Raman spectroscopy (CRS) and multivariate analysis for classification of sperm cells. The spectral based classification is compared with the morphological analysis, which is the main criterion for sperm selection in intracytoplasmic sperm injection procedure. The spectral analysis is conducted using the data driven soft independent modeling of class analogies method. The supervised classification reveals numerous outliers that pass from the 'normal' class to the 'abnormal' class, and vice versa. The ultimate result shows that the initial morphological discrimination overlaps with the spectral classification only partly. It is shown that CRS provides additional information regarding the nuclear DNA stability and helps to reveal spermatozoa with fragmented and defective DNA. This can be a promising direction for future evaluation of spectra from live, unfixed cells.