Species-specific developmental timing is maintained by pluripotent stem cells ex utero

Abstract

How species-specific developmental timing is controlled is largely unknown. By following human embryonic stem (ES) cell and mouse epiblast stem (EpiS) cell differentiation through detailed RNA-sequencing time courses, here we show that pluripotent stem cells closely retain in vivo species-specific developmental timing in vitro. In identical neural differentiation conditions in vitro, gene expression profiles are accelerated in mouse EpiS cells compared to human ES cells, with relative rates of differentiation closely reflecting the rates of progression through the Carnegie stages in utero. Dynamic Time Warping analysis identified 3,389 genes that were regulated more quickly in mouse EpiS cells, and identified none that were regulated more quickly in human ES cells. Interestingly, we also find that human ES cells differentiated in teratomas maintain the same rate of differentiation observed in vitro, in spite of being grown in a mouse host. These results suggest the existence of a cell autonomous, species-specific developmental clock that pluripotent stem cells maintain even out of context of an intact embryo.

Epigenetic Priming of Human Pluripotent Stem Cell-Derived Cardiac Progenitor Cells Accelerates Cardiomyocyte Maturation

“…This segmentation clock results from cyclic activation of Notch, Wnt/β‐catenin, and FGF signaling leading to phasic expression of downstream genes . Species‐specific differences in developmental kinetics also suggest developmental clock function in various progenitor populations . In cardiac development, a developmental clock regulating differentiation and maturation of cardiomyocytes has not been well defined, but our results suggest that subsets of early cardiomyogenic and Notch gene expression programs are involved in this function.…”

“…Although environmental cues clearly modulate cardiomyocyte development, there is evidence that cell-intrinsic processes also regulate the time course of maturation. For example, studies comparing mouse PSC and hPSC differentiation demonstrate species-specific differences in the kinetics of differentiation both in vitro and during in vivo teratoma formation suggesting a cell autonomous developmental clock [24]. Consistent with an intrinsic developmental clock, distant cardiomyocytes found in pulmonary and azygous veins show maturational changes in troponin and myosin isoforms that are synchronous in time with cardiomyocytes of the heart proper, although spatially remote and subject to dramatically different hemodynamics and cell signaling [25].…”

P63 expression plays a role in developmental rate, embryo size, and local morphogenesis

“…While changes in rate and period of development can generate healthy phenotypic variation (Minoux and Rijli, 2010;Saiz-Lopez et al, 2015;Barry et al, 2017), developmental timing is also a threshold between normal morphogenesis and malformation, such as in facial dysmorphologies (Lan et al, 2015;Marcucio et al, 2015). Potentially delayed development related to p63 misexpression merits investigation to identify which traits in the p63 mutant phenotype are due to structures that are simply underdeveloped and asynchronous vs. structures that are malformed and pathological.…”

A novel self-organizing embryonic stem cell system reveals signaling logic underlying the patterning of human ectoderm

“…Incorporating WNT or BMP4 has been shown to yield neural crest progenitors (Leung et al, 2016;Tchieu et al, 2017). Achieving pure populations of cells is likely essential in some applications, however the complexity of human development involves multiple self-organizing cell types whose patterning differs notably from other mammals and model organisms (Barry et al, 2017;Bock et al, 2018). Studying human ectodermal patterning requires developing in vitro models in which cells self-organize and spatiotemporal patterns emerge reproducibly in a fashion similar to that of the human embryo in vivo.…”