More than 20 years ago, the lab of developmental biologist Olivier Pourquié discovered a sort of cellular clock in chicken embryos where each “tick” stimulates the formation of a structure called a somite that ultimately becomes a vertebra.
In the ensuing years, Pourquié and others further illuminated the mechanics of this so-called segmentation clock across many organisms, including creation of the first models of the clock in a lab dish using mouse cells.
While the work has improved knowledge of normal and abnormal spine development, no one has been able to confirm whether the clock exists in humans — until now.
Pourquié led one of two teams that have now created the first lab-dish models of the segmentation clock that use stem cells derived from adult human tissue.
The achievements not only provide the first evidence that the segmentation clock ticks in humans but also give the scientific community the first in vitro system enabling the study of very early spine development in humans.
“We know virtually nothing about human development of somites, which form between the third and fourth week after fertilization, before most people know they’re pregnant,” said Pourquié, professor of genetics in the Blavatnik Institute at Harvard Medical School and a principal faculty member of the Harvard Stem Cell Institute. “Our system should be a powerful one to study the underlying regulation of the segmentation clock.”
“Our innovative experimental system now allows us to compare mouse and human development side by side,” said Margarete Diaz-Cuadros, a graduate student in the Pourquié lab and co-first author of the HMS-led paper, published Jan. 8 in Nature. “I am excited to unravel what makes human development unique.”