Computer-Aided Sperm Analysis (CASA) of sperm motility and hyperactivation

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Within the male reproductive system, the epididymis is a secretory tubule attached to the testis in which spermatozoa will sequentially interact with extracellular factors to acquire their motility and fertilizing ability. Although this post-testicular maturation process is essential for the control of male reproductive functions, the cellular and molecular mechanisms involved remain obscure. In this context, my NSERC-funded research program aims to decipher the fundamental intercellular communication mechanisms that control epididymal functions and sperm maturation. In particular, we are exploring the role of mediators of extracellular communication such as the primary cilia (PC) and extracellular vesicles (EV) in the transfer of bioactive molecules from a donor cell to a recipient cell. Among other things, we unveiled the presence of EVs derived from CP in the male reproductive system (unpublished data) and the existence of a paracrine communication system between the somatic cells of the epididymis (Jerczynski et al. al, PLoSOne 2016, Principal investigator, transgenic mouse model) as well as between somatic cells and spermatozoa (Sharma et al, Science, 2016, Collaborator, murine and bovine models; Alves et al, 2020, Frontiers in Cell and Developmental Biology, Principal investigator) via the vesicular transport of small non-coding RNAs. Although EV and other extracellular factors ensure the change in the sperm molecular pattern, we wish to evaluate their contribution in the acquisition of sperm motility, an essential parameter for maintaining male fertilizing abilities. In this perspective, we wish to acquire state-of-the-art kinetic imaging equipment such as the Computer Assisted Sperm Analysis (CASA). This equipment is essential for the quantitative and standardized analysis of sperm factors such as progressive motility, morphology, concentration and the presence of DNA fragmentation. Hamilton Thorne Inc's IVOS II-CASA system is an example of a CASA system that is used by leading andrology laboratories around the world for its versatility since it can be used in fundamental studies on small rodents (e.g. transgenic mice or mice genetically invalidated for ciliary or vesicular components) and large mammals (e.g. bovines). Beyond improving our understanding of the cellular and molecular mechanisms that govern the control of the fertilizing power of mammals, the use of this cutting-edge equipment in the context of our work will open up new perspectives for the breeding industry where the increase in the inbreeding coefficient of animals affects reproductive performance.