Stem cell-based genesis
Stem cells are the seeds of organisms, with the capacity to multiply, generate specialized cells, and organize into sophistically patterned and functional tissues and organs. Stem cells achieve such complex behaviour via their genetically encoded molecular networks and dynamic communication mechanisms, which allow them to take both autonomous and coordinated decisions.
We seek for the general principles underlying the organization of stem cells that lead to the formation of organisms. To reveal these principles, we form models of organisms in-a-dish by harnessing the intrinsic potential of stem cells to self-organize. This approach allows to more systematically modulate and analyse behaviour, while generating large numbers of embryo models for drug and genetic screens, biochemistry and genomic analysis.
Our group gathers embryologists, stem cell biologists, genetic engineers, and computational biologists, and is grounded in fundamental stem cell biology and in technology development including microsystems, 3D high-content imaging screens, single cell genomics, computational analysis, and collaborations with theoretical physicists.
We develop these novel embryo models not only to investigate the design principles governing development but also with the long-term goal of improving global health problems related to reproduction. Indeed, the first weeks of human pregnancy are crucial as early abnormalities or insults result in infertility. Therapeutics acting at the onset of embryonic development would offer opportunities to improve public health through effective family planning and to reduce an ongoing global fertility decrease with profound economic, social, environmental, and geopolitical consequences. Unfortunately, a drug development program on human embryos is unfeasible due to the inaccessibility and scarcity of embryos, and to ethical issues associated with them. As a result, the attrition rate of drugs for reproductive health is high for all major In Vitro Fertilization (IVF) and pharmaceutical companies. Because stem cells can be largely multiplied, blastoids provide a scalable and ethical alternative amenable to drug screens, thus opening numerous possibilities for therapeutic breakthroughs.
We created an in vitro model of the mammalian blastocyst that we called blastoid. Blastoids comprise analogs of the 3 founding cell types (epiblast, trophoblast, primitive endoderm), and recapitulate aspects of development and implantation.
We develop technologies based on microfabrication, synthetic biology, high-content imaging, and single cell transcriptomic in order to understand self-organization.
Stem cells have the inherent capacity to self-organise and recapitulate development. Capitalising on this, we guided stem cells to form the first model of a blastocyst in-a-dish (blastoids). Blastoids form through the assembly of trophoblast stem cells and embryonic stem cells (mouse) and through the self-organization of PXGL pluripotent stem cells (human). They morphologically and transcriptionally resemble the pre-implantation blastocyst and upon in vitro development, form analogs of the three founding cell types of the conceptus (epiblast, trophoblast, primitive endoderm) and acquire the capacity to recapitulate aspects of implantation in utero and in vitro for mouse and human blastoids, respectively.
Blastoids are scientific models that reveal the design principles of development. Up to now, they exposed that, at this early stage, the embryonic cells produce numerous inductive signals that guide the proliferation, self-renewal, morphogenesis, and patterning of the trophoblast cells (the future placenta). Altogether, these embryonic inductions gatekeep the potential for the embryo to implant in utero. Blastoids reveal principles for promoting stem cell self-organisation in a dish, and could contribute, on the long term, to understand and test solutions to problems of infertility, pregnancy failure or the embryonic origin of diseases.
1: Human blastoids model blastocyst development and implantation. Kagawa H, Javali A, Khoei HH, Sommer TM, Sestini G, Novatchkova M, Scholte Op Reimer Y, Castel G, Bruneau A, Maenhoudt N, Lammers J, Loubersac S, Freour T, Vankelecom H, David L, Rivron N. Nature. 2022 Jan;601(7894):600-605. doi: 10.1038/s41586-021-04267-8. Epub 2021 Dec 2. PMID: 34856602
2. Embryonic signals perpetuate polar-like trophoblast stem cells and pattern the blastocyst axis. Frias-Aldeguer J, Kip M, Vivié J, Li L, Alemany A, Korving J, Darmis F, van Oudenaarden A, Van Blitterswijk CA, Geijsen N, Rivron NC*. BioRxiv 510362; doi: https://doi.org/10.1101/510362
3: Chemically-defined induction of a primitive endoderm and epiblast-like niche supports post-implantation progression from blastoids. Vrij EJ, Scholte op Reimer YS, Frias Aldeguer J, Misteli Guerreiro I, Kind J, Koo BK, van Blitterswijk CA, Rivron NC*. BioRxiv 510396; doi: https://doi.org/10.1101/510396.
4: Blastocyst-like structures generated solely from stem cells. Nicolas C Rivron [corresponding author], Javier Frias-Aldeguer, Erik J Vrij, Jean-Charles Boisset, Jeroen Korving, Judith Vivié, Roman K Truckenmüller, Alexander van Oudenaarden, Clemens A van Blitterswijk *, Niels Geijsen * [* equal contribution]. Nature. 2018.
5: In vitro generation of blastoids from trophoblast and embryonic stem cells. Nicolas C Rivron. Protocol exchange. 2018.
6: Kicheva A, Rivron NC. Creating to understand - developmental biology meets engineering in Paris. Development. 2017 Mar 1;144(5):733-736. doi:10.1242/dev.144915. PubMed PMID: 28246208.
Self-organization is a fascinating family of mechanisms underlying the formation of patterns of behaviors in populations. It has been mathematically resolved to explain the behaviour of populations of animals (e.g., ants, bees). For example, fish schools, ant colonies and bird flocks coordinate their collective behaviors to control the emergence and progression of patterns and functions. This broad range of mechanisms is decentralized, adaptive, and based on dynamic local interactions. However, it remains unknown to which extent the same mechanisms apply to the multicellular processes of embryonic development. We explore how self-organization complements traditional hierarchical genetic (e.g., HOX genes collinearity) and molecular (e.g., morphogen gradients) processes to shape the mammalian organism.
Unleashing the intrinsic potential for stem cells to spontaneously organize in-a-dish requires to precisely control simple boundary conditions (e.g., cell number, confinment, multicellular geometry). We developed microfabrication, computational, and genetic technologies to establish these boundary conditions, modulate and monitor behaviours at the single cell level. These tools increase the reproducibility, throughput, and prediction of stem cell behaviours, and are thus empowering for scientific discoveries.
1: Kicheva A, Rivron NC. Creating to understand - developmental biology meets engineering in Paris. Development. 2017 Mar 1;144(5):733-736. doi:10.1242/dev.144915. PubMed PMID: 28246208.
2: Vrij E, Rouwkema J, LaPointe V, van Blitterswijk C, Truckenmüller R, Rivron N. Directed Assembly and Development of Material-Free Tissues with Complex Architectures. Adv Mater. 2016 Jun;28(21):4032-9. doi: 10.1002/adma.201505723. Epub 2016 Mar 22. PubMed PMID: 27000493.
3: Vrij EJ, Espinoza S, Heilig M, Kolew A, Schneider M, van Blitterswijk CA, Truckenmüller RK, Rivron NC. 3D high throughput screening and profiling of embryoid bodies in thermoformed microwell plates. Lab Chip. 2016 Feb 21;16(4):734-42. doi: 10.1039/c5lc01499a. Epub 2016 Jan 18. PubMed PMID:26775648.
4: Leferink A, Schipper D, Arts E, Vrij E, Rivron N, Karperien M, Mittmann K, van Blitterswijk C, Moroni L, Truckenmüller R. Engineered micro-objects as scaffolding elements in cellular building blocks for bottom-up tissue engineering approaches. Adv Mater. 2014 Apr 23;26(16):2592-9. doi: 10.1002/adma.201304539. Epub 2014 Jan 7. PubMed PMID: 24395427.
5: Fennema E, Rivron N, Rouwkema J, van Blitterswijk C, de Boer J. Spheroid culture as a tool for creating 3D complex tissues. Trends Biotechnol. 2013 Feb;31(2):108-15. doi: 10.1016/j.tibtech.2012.12.003. Epub 2013 Jan 18. Review. PubMed PMID: 23336996.
6: Rivron NC, Vrij EJ, Rouwkema J, Le Gac S, van den Berg A, Truckenmüller RK, van Blitterswijk CA. Tissue deformation spatially modulates VEGF signaling and angiogenesis. Proc Natl Acad Sci U S A. 2012 May 1;109(18):6886-91. doi:10.1073/pnas.1201626109. Epub 2012 Apr 17. PubMed PMID: 22511716; PubMed Central PMCID: PMC3344996.
7: Rivron NC, Raiss CC, Liu J, Nandakumar A, Sticht C, Gretz N, Truckenmüller R, Rouwkema J, van Blitterswijk CA. Sonic Hedgehog-activated engineered blood vessels enhance bone tissue formation. Proc Natl Acad Sci U S A. 2012 Mar 20;109(12):4413-8. doi: 10.1073/pnas.1117627109. Epub 2012 Mar 2. PubMed PMID:22388744; PubMed Central PMCID: PMC3311342.
8: Rouwkema J, Rivron NC, van Blitterswijk CA. Vascularization in tissue engineering. Trends Biotechnol. 2008 Aug;26(8):434-41. doi:10.1016/j.tibtech.2008.04.009. Epub 2008 Jun 26. Review. PubMed PMID: 18585808.
9: Rivron NC, Rouwkema J, Truckenmüller R, Karperien M, De Boer J, Van Blitterswijk CA. Tissue assembly and organization: developmental mechanisms in microfabricated tissues. Biomaterials. 2009 Oct;30(28):4851-8. doi:10.1016/j.biomaterials.2009.06.037. Epub 2009 Jul 9. PubMed PMID: 19592088.