The symposium will take place at the Fira de Montjuïc congress centre in Barcelona from 12 to 14 November. Researchers from the UAB and other institutions will be presenting a new way to preserve human sperm in extreme conditions, research on the harmful effects of microplastics on mammalian reproduction, and the identification of new molecular mechanisms involved in male infertility.
The 13th edition of the ASEBIR embryology association congress, which this year breaks the record for attendees (over 600) and communications (over 240), will take place for the first time in Barcelona, at the Fira de Montjuïc congress centre, from 12 to 14 November. The opening ceremony will be presented by biologist Anna Veiga, founder of ASEBIR; Antonio Urries, president of ASEBIR; Lluís Tort, UAB lecturer and dean of the Association of Biologists of Catalonia; and Marta Villanueva Cendán, Barcelona City Council Health Councillor.
UAB researchers will present several works, including the following:
Can lyophilisation of human sperm be considered a real option for cryopreservation in extreme environments?
A collaboration between the Biology team at Dexeus Dona and the Department of Cell Biology at the Universitat Autònoma de Barcelona demonstrates that lyophilisation does not cancel out the fertilisation capacity of sperm, since once injected into hamster oocytes, transcription of sperm DNA is observed.
Sperm preservation by lyophilisation has been shown to be effective in multiple species. Fertilisation, embryonic development, and offspring have been achieved after microinjection of lyophilised and subsequently rehydrated sperm into mice, rats, rabbits, and horses, suggesting that the functional capacity of sperm DNA is maintained. However, experience with human sperm is very limited. Preliminary studies have already observed that lyophilised sperm do not regain their motility after rehydration for reproductive purposes.
The novelty of this study is that it has demonstrated that freeze-dried human sperm, after being rehydrated and microinjected into hamster oocytes (the most similar to human oocytes available for experimental use), have the capacity to activate the oocyte, sustain the formation of pronuclei, and transcribe its DNA. The results open up the possibility of evaluating the use of this technique in extreme situations or remote places, such as desert areas or outer space, where it is not possible to cryopreserve human sperm with current techniques due to the impossibility of using liquid nitrogen.
Impact of exposure to nanoplastics on mammalian gametes and preimplantation embryos
One of the factors that has been linked to the recent increase in human infertility is exposure to emerging environmental pollutants. Among these are microplastics and nanoplastics. In this study, which will be presented in one of the two invited papers of the inaugural session, the direct toxic effects of nanoplastics on oocytes, spermatozoa and preimplantation embryos of mammals were evaluated, using mice as models.
The results demonstrate that nanoplastics are capable of adhering to the plasma membrane of sperm, compromising essential parameters for their fertilisation capacity such as motility, membrane integrity, and the ability to carry out the acrosomal reaction. In contrast, oocytes and preimplantation embryos would be protected from the harmful effects of these contaminants thanks to the zona pellucida that surrounds them. However, damage to this protective barrier or its loss during the natural process of embryonic hatching facilitates the internalisation of nanoplastics in the cells, reducing the viability and quality of the embryos and potentially compromising their implantation capacity.
These findings highlight the urgent need to continue investigating the effects of nanoplastics on human reproductive health and to promote measures to reduce environmental exposure, with the aim of protecting fertility and guaranteeing the health of future generations. The study was led by Dr Elena Ibáñez de Sans from the Department of Cell Biology, Physiology and Immunology at the UAB.
New molecular mechanisms involved in male infertility
The UAB Genetics of Male Fertility research group will present two significant advances in understanding the molecular basis of male infertility, a condition that affects approximately 7% of men of reproductive age. The studies reveal both new biomarkers for the diagnosis of infertility, and fundamental cellular mechanisms in sperm formation.
In the work entitled "Sperm mRNA Transcriptomics as a Diagnostic and Prognostic Tool in Male Infertility", sperm transcriptome is presented as a precision diagnostic tool. Researchers analysed the expression profile of messenger RNA (mRNA) in sperm from fertile and infertile men, in collaboration with the Dexeus University Hospital, Fertilab and Reproclinic. The study identified a set of genes with differential expression that would explain the differences in semen characteristics between fertile donors and infertile patients, and the variations observed between patients with good or poor results in assisted reproductive techniques (ART). These results suggest that certain sperm mRNA transcripts could be used as diagnostic and prognostic tools, allowing a more precise and personalised assessment of male infertility.
The second study, entitled "Homologous Chromosome Pairing Precedes Meiosis Onset and is Regulated by SYCP3 and SIRT7," reveals a novel role for SYCP3 and SIRT7 before meiosis. The research reveals that homologous chromosome pairing, a key step in sperm formation, begins before the onset of meiosis. Using mouse models, the researchers demonstrated that the absence of the SYCP3 and SIRT7 genes significantly reduces the ability of germ cells to correctly pair homologous chromosomes, which could compromise the formation of viable gametes. This discovery redefines the initial stages of spermatogenesis and provides new clues about the molecular mechanisms that ensure male fertility.
Both studies received support from projects funded by the Carlos III Health Institute, the Agency for Management of University and Research Grants (AGAUR), and the Universitat Autònoma de Barcelona (UAB) itself.
The congress organised by ASEBIR has been held continuously since 2001 and its objective is to promote research and knowledge in the field of reproductive science, as well as to encourage the exchange of opinions and the establishment of new contacts between professionals.
