UCLA researchers find blood stem cells originate and are nurtured in th...(they need. It was previously known ...),Health

It was previously known that blood stem cells could be found in the dorsal aorta, but there were so few located there that scientists reasoned it could not be the sole source of blood stem cells in the embryo. Mikkolas discovery indicates that the blood stem cells are generated in the large arteries of the embryo and placenta, and then move to a specific site, or niche, where they expand and mature.

This recent study indicates that the first niche for expansion of blood stem cells is the placentas vascular labyrinth, where oxygen and nutrients are exchanged between the mother and the fetus. The findings show the placenta harbors two different microenvironments, one area where blood stem cells originate and another area, the labyrinth, that nurtures them, allowing them to expand in number. These niches serve different roles and could provide clues to researchers seeking to grow blood stem cells. Mikkola now is seeking to uncover the critical biological signals and cues during embryonic development that drive blood stem cell generation and expansion and keep the cells from differentiating prematurely.

The labyrinth is a source of many growth factors and cytokines, Mikkola said. We just need to identify what those signaling molecules and cues are that are nurturing those cells when in the placenta.

Mikkola is confident the study can be confirmed in humans.

Everything were learning suggests we will find the same thing in the human placenta, she said.