Our study “An in vitro model for anteroposterior organisation during human development” is out! nature.com/articles/s4158… @nature @Cambridge_Uni @_Hubrecht A summary: (1/10)
In this study, we used human Embryonic Stem Cells that we disassociate and resuspend together into small, spherical 3D aggregates. Remarkably, these are able to spontaneously break symmetry, and, over 3 or 4 days, they elongate along a single anterior-posterior axis (2/10) 
Using a triple-coloured reporter of the 3 germ layers, we saw that these aggregates had polarised expression of Brachyury at the most distal end, and they express all three fluorescent reporters in an organised manner (3/10)
In embryos, the process of developing 3 germ layers, elongating along an axis and organising the body plan is known as ‘gastrulation’, so we call these structures: #humangastruloids (4/10)
In collaboration with colleagues @_Hubrecht we applied the tomo-seq technique: cryosections of human gastruloids were taken along the AP axis and each slice was RNA-seq profiled to build a picture of the gene expression organisation along the axis of human gastruloids (5/10)
Remarkably, we found that many genes were reproducibly expressed at defined positions along the length of the AP axis. In particular, genes typically found in the tailbud of the mammalian embryo were in the posterior of the human gastruloids, and vice versa (6/10)
However, similar to our previous research using mouse #gastruloids, we found no evidence of anterior neural or extraembryonic cell types in the structures (see nature.com/articles/s4158… for instance) (7/10)
We were, however, surprised to see a signature of somitogenesis along the AP axis of human gastruloids, with genes associated with the tailbud, PSM, and somitic mesoderm expressed in order. In the human embryo, somites appear around day 18-20 of development (8/10)
We are hopeful that our work will open up new avenues for researching human-specific development, including how cell fate decisions are coordinated to establish the organisation of the bodyplan, and investigate molecular mechanisms and general principles of human dev (9/10)
I want to extend a huge thank you to all authors, Kerim Anlas, @SusannevdBrink @annionna Julia Schroder, @SabitriGhimire2 Tina Balayo, @AlexandervanOu1 and @AMartinezArias as well as reviewers and funders for their contribution to this study! (10/10)
