Non-invasive metabolomic profiling of culture media of ICSI- and IVF-derived early developmental cattle embryos via Raman spectroscopy.

The aim of the present study was to compare differences in composition between in vitro cultured early developmental embryos resulting from either in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Non-invasive metabolomic profiling of culture media was conducted with laser tweezer Raman spectroscopy (LTRS), providing molecular information that was used to aid the diagnosis or treatment of embryos that were adversely affected by ICSI treatment, ultimately improving the ICSI embryonic developmental potential. Cattle embryos were generated via ICSI and IVF with development to the 2-, 4-, 8-, 16-,32-cell, and blastocyst stages with individual in vitro culturing occurring for 4 h. The culture media for embryos in different developmental stages were separately analyzed using LTRS. The resulting composition of culture media used for culturing IVF- and ICSI-derived embryos was mainly altered in contents of carbohydrates, lipids, DNA, and proteins. Bands at 1004 cm-1 (phenylalanine) and 1529 cm-1 (-C = C-carotenoid) had specific patterns related to the metabolicactivity of embryos; using LTRS, and these may be considered as biomarkers for embryonic development. Furthermore, the vibrations of lipids at different stages increased more with assessment of ICSI culture media than in IVF media. Discriminant function analysis can be utilized for the classification of culture media used for culture of ICSI- and IVF-derived embryos. In conclusion, LTRS can be used for development of an independent assay to assess embryo status during both ICSI and IVF procedures, which provides novel insights into differences in structure and components of single cells.