O-003 Mechanics of human embryo compaction

Abstract Study question How the human embryo builds blastocyst is crucial to improve ART, as morphology of a prime determinant assess implantation potential. Summary answer An evolutionarily conserved increase in cell contractility required generate forces driving compaction, which first morphogenetic event shaping body. What known already The begins with during cells come into close contact and form tighter structure. ART studies suggest that embryos fail compaction primarily because defective adhesion. Based on our current understanding animal morphogenesis, other engines, such contractility, could be involved embryo. However, molecular, cellular physical mechanisms morphogenesis remain uncharacterized. design, size, duration A total 54 frozen have been used for this work. use donated research was allowed by Agence de la Biomédecine (approval number RE 17-011R) compliance International Society Stem Cell Research guidelines. Donated were cryopreserved stored at three different centers Paris. Embryos then transferred Institut Curie where they immediately thawed project. Participants/materials, setting, methods Using micropipette aspiration embryos, we mapped surface tensions compaction. Drug inhibition immunostaining cell-cell adhesion reveal what drives tension responsible To evaluate focused F-actin myosin motor proteins, E-cadherin. Main results role chance Mapping reveals 4-fold cell-medium interface, from 0.62 ± 0.04 2.35 0.08 nN/µm (mean SEM 147 measurements 10 Student’s t test p < 10-5), while contacts keep steady ∼0.6 nN/µm. Therefore, increased interface qualitatively similar mouse (from ∼0.2 0.4 nN/µm). Further comparison between but quantitavely mechanical strategies, being mechanically least efficient. Inhibition that, both processes are involvement plays permissive role. Only controls Interestingly, exhibit distinct signatures when faulty. Analyzing signature naturally failing find evidence non-compacting or partially compacting excluded contractility. Limitations, reasons caution Given need research, valuable samples, sample size small sufficient show statistically significant differences. Moreover, these infertile patients undergoing ART. Wider implications findings Excluded aneuploid protect embryonic tissue chromosomal abnormalities. Is there correlation their fact may remains an open question. laws produce breathtaking diversity shapes life? Trial registration ‘not applicable'