Stem cells are produced by bone marrow and can turn into different types of blood cellsKATERYNA KON / SPL/ Alamy
Human blood stem cells have been made in a laboratory for the first time, which could significantly improve how we treat certain types of cancer.
The lab-grown cells have so far only been tested in mice, but when infused into the animals, the cells became functional bone marrow at similar levels to those seen after umbilical cord blood cell transplants.

Treating cancers such as leukaemia and lymphoma via radiation and chemotherapy can destroy the blood-forming cells in bone marrow. A stem cell transplant means that new, healthy bone marrow and blood cells can grow. Umbilical cords are a particularly rich source of stem cells, but donations are limited and the transplant can be rejected by the body.
The new method would allow researchers to produce stem cells from the actual patient, eliminating the supply issue and reducing the risk that their body would reject them.
First, human blood or skin cells were turned into so-called pluripotent stem cells through a process called reprogramming. “This involves temporarily turning on four genes, with the result that the patient cells revert to an early stage of development when they can become any cell in the body,” says Andrew Elefanty at the Murdoch Children’s Research Institute in Melbourne.
The second stage involved turning the pluripotent cells into blood stem cells. “We first make thousands of small floating balls of cells, a few hundred cells in each ball, and direct them to change from being stem cells to sequentially become blood vessels and then blood cells,” says Elefanty. This process, called differentiation, takes about two weeks and makes millions of blood cells, he says.
These cells were then infused into mice that lacked an immune system and became functional bone marrow in up to 50 per cent of cases. This means it made the same cells that carry oxygen and fight infections as healthy human bone marrow does, says Elefanty. “It is this unique ability to make all the blood cell types for a prolonged period of time that defines the cells as blood stem cells,” he says.
Abbas Shafiee at the University of Queensland in Brisbane says the work is a “magnificent breakthrough” towards new therapies for blood cancers. “It has not been done before and it has a lot of potential for the future.” But even once animal testing is complete, a lot of research in humans needs to be done before the approach can be used in clinics, he says.

Simon Conn at Flinders University in Adelaide, Australia, says a key advantage of the team’s approach is that it could be scaled up to produce “an essentially never-ending supply” of blood stem cells. But he adds that the work was based on either blood or skin cells, with the rate of success and the diversity of the blood cells depending on the initial cell type.
“This suggests the treatment, even at the preclinical stage in mice, is not consistent, which will need to be addressed prior to any clinical trials in human patients,” he says.

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