Lab-grown stem cells could be a ‘breakthrough’ for cancer treatment

Human blood stem cells have been created in a laboratory for the first time, which could significantly improve the way we treat some types of cancer.

So far, the lab-grown cells have only been tested in mice, but when injected into the animals, the cells turned into functional bone marrow at levels similar to those seen after cord blood cell transplants.

Treatment of cancers such as leukemia and lymphoma with radiation and chemotherapy destroys blood-forming cells in the bone marrow. A stem cell transplant means new healthy bone marrow and blood cells can be grown. The umbilical cord is a particularly rich source of stem cells, but donations are limited and transplanted stem cells may be rejected by the body.

The new method will allow researchers to extract stem cells from actual patients, eliminating supply issues and reducing the risk of the patient’s body rejecting the stem cells.

First, human blood or skin cells are converted into so-called pluripotent stem cells through a process called reprogramming. “This involves temporarily switching on four genes, with the result that the patient’s cells revert to an earlier stage of development, at which point they can become any cell in the body,” says Dr. Andrew Elefanti at the Murdoch Children’s Research Institute in Melbourne.

The second stage is to convert the pluripotent cells into blood stem cells. “We first create thousands of floating spheres of cells, with a few hundred cells in each sphere, and then guide them to transform from stem cells to blood vessels and then blood cells,” said Elefanti. This process, called differentiation, takes about two weeks and can produce millions of blood cells, he said.

The cells were then injected into mice lacking an immune system, and in up to 50 percent of cases they became functional bone marrow. That means they made cells that, like healthy human bone marrow, could carry oxygen and fight infection, Elefanty said. “It’s this unique ability to make all blood cell types over an extended period of time that defines these cells as blood stem cells,” he said.

Abbas Shafi Researchers at the University of Queensland in Brisbane said the study was a “major breakthrough” in new treatments for blood cancer. “This is unprecedented and has huge potential for the future,” he said. But he said that even if the animal trials are completed, a lot of research on humans is needed before this approach can be used in the clinic.

Simon Kahn A key advantage of the team’s approach is that it can be scaled up to produce “essentially inexhaustible” blood stem cells, said the researcher from Flinders University in Adelaide, Australia. But he added that the work was based on blood or skin cells, and that the success rate and diversity of blood cells depended on the starting cell type.

“This suggests that even in preclinical stages in mice, this treatment is inconsistent, and this needs to be addressed before any clinical trials in human patients are undertaken,” he said.