Biochemical and physiological characterization of human spermatozoa using novel optical technologies - A new understanding of sperm functional competence

• Applicant: Professor Dr. Stefan Schlatt
• Subject Area: Reproductive Medicine, Urology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 491360700

Clincial and experimental sperm analysis relies on cellular features estimated by light microscopy. Sperm count, morphology and motility are currently determined as the primary endpoints. While these parameters present valuable readouts on gamete production in the testis, the functional features of spermatozoa and specifically their competence to fertilize is not adequately addressed. In recent years several biochemical tests were developed to better identify sperm functional competence. Such strategies are mandatory to improve sperm analysis and sperm selection in human and veterinary medicine. Our group has entered an alternative track by exploring the application of novel and innovative optical strategies for sperm analysis. We obtained many new insights into sperm integrity and function in a number of species and created several new diagnostic strategies. We hypothesize, that non-invasive optical strategies can be applied to obtain functional parameters in individual human spermatozoa. Such endpoints will enable us to describe more precisely the cascade of events a sperm needs to pass before fertilization can occur. Such new findings will change our concept for sperm function and may provide novel strategies for sperm assessment. In this project we describe various parameters on individual sperm providing insights into the integrity and indications for sperm quality. We consider that techniques such as Multiparametric Flow Cytometry (MFC) coupled to cell sorting and Raman Micro-spectroscopy (RM) offer outstanding diagnostic opportunities. We expect, that such findings change the understanding of the mechanisms rendering spermatozoa fertilization competent. Combination of several endpoints offers the potential to assess sperm quality/function far beyond cytological/microscopic parameters. The new optical technologies waived technical limitations and now enable exploration of individual sperm. We can identify quantitatively subpopulations of sperm with none, one or several defects. For the first time, we can determine simultaneously the relationship between various functional cellular features. Our hypothesis-driven approach has the potential to revolutionize our understanding of sperm function and may lead to novel applications for sperm analysis and sorting.

• DFG Programme: Research Grants
• International Connection: Portugal
• Cooperation Partner: Dr. Sandra Amaral