Milestone in quest to make blood cells

Scientists have unveiled two methods for coaxing stem cells into blood cells, a long-sought goal that could lead to new treatments for blood disease, including leukaemia. PHOTO | FILE

What you need to know:

  • They began by inducing both embryonic stems cells and iPS to morph into a form of embryonic tissue that gives rise to blood stem cells.
  • In the second step, they experimented with dozens of proteins known to control gene expression, especially during the formative process of embryo growth.

Scientists have unveiled two methods for coaxing stem cells into blood cells, a long-sought goal that could lead to new treatments for blood disease, including leukaemia.

In separate experiments reported in Nature — one with mice, the other transplanting human stem cells into mouse bone marrow — researchers demonstrated techniques with the potential to produce all types of blood cells.

“This step opens up an opportunity to take cells from patients with genetic blood disorders, use gene editing to correct their genetic defect, and make functional blood cells,” said Ryohichi Sugimura, a doctor at Boston Children’s Hospital and lead author of one of the studies. If proven safe, the proof-of-concept methods could also lead to a “limitless supply of blood” by using cells from universal donors.

Human embryonic stem cells — generic cells which, as the embryo develops, gradually differentiate — were first isolated in 1998. 

THREE STEPS

A decade later, scientists figured out how to generate another type of all-purpose cell from human skin, known as induced pluripotent stem cells, or iPS. These were successfully used to make neurons and heart cells. But the goal of creating blood-forming stem cells in the lab remained out-of-reach. Sugimura and colleagues devised a three-step process to achieve that breakthrough.

They began by inducing both embryonic stems cells and iPS to morph into a form of embryonic tissue that gives rise to blood stem cells. In the second step, they experimented with dozens of proteins known to control gene expression, especially during the formative process of embryo growth.

Five of these transcription factors, working together, yielded the elusive blood stem cells — the starter kit for white and red blood cells, platelets, macrophages and all the other blood cells. Finally, they transplanted these human blood stem cells into the bone marrow of live mice. Within a few weeks, several kinds of human blood cells had formed, and were circulating in the rodents.

In the second study, a team led by Shahin Rafii at Weill Cornell Medicine in New York City used adult mouse cells as their starting material, and then guided them through several steps to create mature blood stem cells in a petri dish.

Taken together, the two experiments “represent a milestone” in stem cell development.

The ability to manufacture blood cells in the laboratory holds enormous promise for cell therapy, drug screening and studies of leukaemia development.