Some research techniques are downright pricey. Others, not so much:
Researchers have managed to grow large numbers of blood-forming stem cells in the lab using a surprisingly simple ingredient found in glue. And when injected into mice, the cells started producing key components of blood.
“The finding is very unexpected and exciting,” says John Dick, a stem-cell biologist at the Prince Margaret Cancer Centre in Toronto, Canada.
If the technique can be applied to humans, it could be used to grow blood stem cells for use in people with blood cancers such as leukemia whose immune systems have been damaged by chemotherapy. The approach could also provide a safer way to treat people with blood disorders, such as sickle-cell disease, who currently have to undergo a risky procedure before receiving a bone-marrow transplant.
This sort of thing has been on researchers’ lists of desiderata for years:
Researchers have been trying for decades to grow in the lab large numbers of “hematopoietic” blood stem cells (HSCs), which regenerate themselves and give rise to other blood components. But until now, none had been able to produce the number needed to reliably engraft — or start producing blood cells — when reintroduced into the body.
Stem-cell biologist Hiromitsu Nakauchi, who leads teams at the University of Tokyo and Stanford University in California, reports in Nature on 29 May how his team managed to successfully engraft HSCs in mice1. The researchers first expanded a cluster of mouse HSCs to almost 900 times its original level in just a month, then transplanted them back into a different set of mice, where they thrived and developed into blood components. “This has been my life goal,” he says.
Okay, what’s the trick?
Researchers looking for ways to grow HSCs in large numbers in the lab had tried using growth factors without much success. But Nakauchi found that the reason the cells weren’t surviving was impurities in the medium in which the cells were being grown, a human blood protein called albumin. These impurities, mostly proteins released by immune cells, were stopping the cells from growing, says Nakauchi. “How much money, time, and effort has been wasted because of those impurities!” he says.
Nakauchi screened a bunch of polymers that he thought could replace albumin, and found that a synthetic compound called polyvinyl alcohol (PVA), often used in glues, did the trick. PVA has also been used to culture embryos and embryonic stem cells. “It’s quite easy. People can go to Safeway and get glue,” Nakauchi says. Laboratory versions of PVA work better than those from the supermarket, he says, and the polymer, which is used in tablet coatings, is deemed non-toxic by regulatory agencies.
Cite: Nature 570, 17-18 (2019)