FTIR Spectroscopy to Reveal Lipid and Protein Changes Induced on Sperm by Capacitation: Bases for an Improvement of Sample Selection in ART

• Main Authors: Maria Pachetti, Luisa Zupin, Irene Venturin, Elisa Mitri, Rita Boscolo, Francesco D’Amico, Lisa Vaccari, Sergio Crovella, Giuseppe Ricci, Lorella Pascolo
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: International Journal of Molecular Sciences
• Subjects: sperm; infertility; FTIR; lipids
• Online Access: https://www.mdpi.com/1422-0067/21/22/8659
• ISSN: 1661-6596; 1422-0067

Although being a crucial step for Assisted Reproduction Technologies (ART) success, to date sperm selection is based only on morphology, motility and concentration characteristics. Considering the many possible alterations, there is a great need for analytical approaches allowing more effective sperm selections. The use of Fourier Transform Infrared (FTIR) may represent an interesting possibility, being able to reveal many macromolecular changes in a single measurement in a nondestructive way. As a proof of concept, in this observational study, we used a FTIR approach to reveal features related to sperm quality and chemical changes promoted by in vitro capacitation. We found indication that α-helix content is increased in capacitated sperm, while high percentages of the β-structures seem to correlate to poor-quality spermatozoa. The most interesting observation was related to the lipid composition, when measured as CH₂/CH₃ vibrations (ratio 2853/2870), which resulted in being strongly influenced by capacitation and well correlated with sperm motility. Interestingly, this ratio is higher than 1 in infertile samples, suggesting that motility is related to sperm membranes stiffness and lipid composition. Although further analyses are requested, our results support the concept that FTIR can be proposed as a new smart diagnostic tool for semen quality assessment in ART.