Stories about: pluripotency

Poised pluripotency: A glimpse of the early embryo just as it’s implanting

poised pluripotency - a newly defined stem cell state
Fawn Gracey illustration (click to enlarge)

Stem cell researchers at Boston Children’s Hospital have, for the first time, profiled a highly elusive kind of stem cell in the early embryo – a cell so fleeting that it makes its entrance and exit within a 12-hour span. They describe this “poised pluripotent” cell in the journal Cell Stem Cell.

In mice, poised cells appear 4.75 to 5.25 days after egg and sperm join to form the embryo, right at the time when the embryo stops floating around and implants itself in the uterine wall.

“People have had a hard time capturing the peri-implantation period because it’s really hard to define,” says Richard Gregory, PhD, who led the research. “It’s a very dynamic stage. Everything happens within a few hours, which is quite remarkable considering the extent of the changes occurring in the properties of the cells.”

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Biological ‘programmers’ crack new code in stem cells

Stem cell colony Wyss Institute James Collins George Daley complexity
Researchers discovered many small nuances in pluripotency states of stem cells by subjecting the cells to various perturbations and then analyzing each individual cell to observe all the different reactions to developmental cues within a stem cell colony. (Credit: Wyss Institute at Harvard University)

Stem cells offer great potential in biomedical engineering because they’re pluripotent—meaning they can multiply indefinitely and develop into any of the hundreds of different kinds of cells and tissues in the body. But in trying to tap these cells’ creative potential, it has so far been hard to pinpoint the precise biological mechanisms and genetic makeups that dictate how stem cells diverge on the path to development.

Part of the challenge, according to James Collins, PhD, a core faculty member at the Wyss Institute for Biologically Inspired Engineering, is that not all stem cells are created the same. “Stem cell colonies contain much variability between individual cells. This has been considered somewhat problematic for developing predictive approaches in stem cell engineering,” he says.

But now, Collins and Boston Children’s Hospital’s George Q. Daley, MD, PhD, have used a new, very sensitive single-cell genetic profiling method to reveal how the variability in pluripotent stem cells runs way deeper than we thought.

While at first glimmer, it could appear this would make predictive stem cell engineering more difficult, it might actually present an opportunity to exert even more programmable control over stem cell differentiation and development than was originally envisioned. “What was previously considered problematic variability could actually be beneficial to our ability to precisely control stem cells,” says Collins.

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