1/n Fun journey continues: Our new @CellStemCell paper out on how the Inherent & Dormant Plasticity of mouse naive PSCs can be "Exaggerated" to Directly form ~E8.5 Transgene-Free (TF) Mouse SEMs & WITHOUT inducing 8-16-Morula-like "Embryo Founder Cells". https://www.cell.com/cell-stem...
2/n a)We previously made mouse SEMs solely from naive PSCs (nPSCs), by use of transgenes to separately induce TE & PrE (Tarazi et al. 2022, https://tinyurl.com/yc7d35tb) b)However, we could make human SEMs from naive PSCs without transgenes (Oldak et al. 2023 https://tinyurl.com/yc623v48)?
3/n c)Human blastoids r made from naive PSCs by simultaneous induction of PrE & TE by CONFUSING the aggregate with a mix of cytokines/small molecules that promote PrE/TE yet maintain some nPSCs. Thus, we wanted to make mouse transgene free TF-SEMs & induce PrE/TE in the same mix?
4/n i)Oldak et al. 2023 we found enhancers of extra-embryonic master regulators largely open in human nPSCs, but not mouse nPSCs, possibly explaining why human SEMs could be made W/O Tg. ii)Consistently, Chambers & co reported HDACi enables TF mouse TSCs https://tinyurl.com/27z9tuz4.
5/n we aimed for "confusing mixed signaling" that partially promote mouse TE & PrE, but retain some PSCs. We tested molecules reported to promote TE/PrE but also boosted iPSCs (alongside HDACi). Briefly, Deng chemical iPSC molecules were top hits (c Fig1) https://tinyurl.com/3bsatkat
6/n 4-day rapid induction & maturation regimen from naive mouse ESCs showed TF induction of TE & PrE that correspond to E3.5-E4.5. Pls note PrE & TE are the only newly induced populations over 4 day time-course!, & there are NO induced 8-16-morula-like embryo founder cells.
7/n Naive pluripotent cells just partially drift towards PrE and TE as can be easily seen below.
8/n consistently given no emergence of new cell populations besides PrE and TE in the induction phase, defining 16cell-morula-like embryo founder master markers genes (https://tinyurl.com/4n23x9h9) were not induced .
9/n We then used electronically controlled ex utero culture device & EUCM conditions we previously developed in Aguilera-Castrejon 2021 http://tinyurl.com/2nuddrnw & generated E8.5 mouse TF-SEMs @enhanced efficiency, from many ESCs & iPSCs & with better quality & somites #
@enhanced 10/n i never get bored from watching them change day by day
@enhanced 11/n My favorite result, is that we could MAINTAIN in this naive alternative condition (AC) media, OCT4/NANOG+ naive PSC colonies that contained OCT4+/Cdx2+ TE primed or OCT4/GATA6 PrE primed double positive cells that self renew for >30 passages. Triple+ cells were very rare!
@enhanced 12/n Naive ESCs in AC-MEF conditions generated advanced E8.5 TF-SEMs. So we developed a rapid induction regimen , and also along-term induction and maintenance based route to make mouse TF-SEMs.
@enhanced 13/n AC-MEF cells were blastoid competent! and TF-SEM competent. They also lacked any 2C-like or 8-16 cell-morula-like embryo founder cells during expansion!
@enhanced 14/n In summary, embryo founder-like cells r neither induced nor involved in TF-SEM formation. there is no evidence that mouse nPSCs need to first go to an earlier "embryo founder cells" & only then give rise to TE/PrE/Epi.
@enhanced 15/n But rather, naive PSCs have minimal plasticity in 2i/LIF shown by Brickman https://tinyurl.com/yhzrducz & our conditions boost amplify this propensity by using alternative signaling conditions. Naive PSCs are de facto totipotent and have "multiple personalities!" C the Matrix!
@enhanced end / Thanks to all Hanna lab members, great collaborators, funders and our lead Heroes from Turkey, @GulbenGurhan and @alperen98yilmaz for the hard work despite of all the noise around.
@jacob_hanna @CellStemCell Congratulations !! Also 👏 to Alperen and @GulbenGurhan !
@Tamer_Onder @CellStemCell @GulbenGurhan Thank u dear Tamer for such great training and sending them my way. @alperen98yilmaz
@jacob_hanna @CellStemCell Congrats Jacob and the team! Can’t wait to read it in detail!
@MoEbrahimkhani @CellStemCell Thank dear MO
@jacob_hanna @CellStemCell Congratulations unbelievable you got this done given the circumstances. I’m so sorry for everybody. I can’t get into it in social media, but the situation is terrible and I’m amazed actually flabbergasted you could do this.
@rweichselbaum @CellStemCell Thank you dear Ralph .. it has been very hard and slow but we do our best. It is so sad all around us and trying to make it despite all.
@jacob_hanna @CellStemCell Congrats Jacob! Looking forward to reading it
@muggi_ @CellStemCell Thank u dear Mehmet . Feel free to send us ur critiques !
@jacob_hanna @CellStemCell Love it!!! 😍
@JonathanBayerl @CellStemCell Thank u and we all miss u Jo