In a scientific feat that almost defies imagination, Canadian researchers have transformed human skin into different types of blood cells.
The achievement by McMaster University scientists is being hailed as a breakthrough that could one day help patients needing transfusions for surgery, to treat potentially deadly blood disorders or to offset the destructive side-effects of chemotherapy.
But it also raises the possibility that other cell types, such as neurons to repair brains damaged by disease or injury, could also be directly induced and grown in the lab using a mere scrap of a person’s own skin.
Principal investigator Mick Bhatia, scientific director of McMaster’s Stem Cell and Cancer Research Institute, said his team was able to produce oxygen-carrying red blood cells, two kinds of immune cells and the cells that produce platelets needed for clotting.
“We have shown this works using human skin,” Bhatia said. “We know how it works and believe we can even improve on the process.”
What’s significant about the research, published online Sunday in the journal Nature, is that the scientists were able to coax mature blood cells from skin without the intermediate step of producing stem cells that would then need to be differentiated into the various blood cell types.
While blood cells could be derived from both embryonic stem cells and what are known as induced pluripotent stem (iPS) cells, the process is far more complicated and time-consuming, as well as being fraught with potential safety problems.
Such blood cells would also be “fetal” in nature — not mature adult cells — with properties that make them unsuitable for transfusion, Bhatia said from Hamilton.
“Because we were starting out with adult fibroblasts (skin cells), we actually made adult blood, which we are predicting is going to be far more useful.”
Skin cells used to generate blood cells came from six individuals who ranged in age from newborn to 65-plus, said Bhatia. “What we found was it didn’t make a difference. We were able to convert all of the human skin cells to blood independent of how aged the person was.”
The skin cells-turned-blood cells were grown in Petri dishes in the lab, then transplanted into specially bred lab mice to see how they behaved.
So far, tests have turned up no evidence of cancerous tumours developing, a danger with both embryonic and iPS cells.
Dr. Cynthia Dunbar of the U.S. National Heart, Lung and Blood Institute said no one has been able to produce mature adult blood cells from embryonic or iPS stem cells, so the McMaster team’s ability to beget them — while detouring around stem cells — is an exciting achievement.
“The ability to do this is going to open a lot of doors in terms of being able to study biology,” Dunbar said from Bethesda, Md.
“In terms of whether it’s going to be put into patients in the next five years, I think that’s very unlikely. But that doesn’t take away from how important it is scientifically and how important it is conceivably for eventual clinical applications.”
Cancer treatment is one area in which a supply of healthy blood cells is critical, said Christine Williams, director of research at the Canadian Cancer Society. For instance, the technique could potentially provide a new source of non-cancerous blood replacement for people with leukemia, who now rely on bone marrow transplants.
For patients with solid organ tumours who are taking high doses or a prolonged regimen of chemotherapy, being able to generate new blood cells from a patient’s own skin would mean not having to interrupt treatment when the drugs begin destroying the blood system.
“The problem is that because of that stop in time to recover, you also give the tumour a chance to regrow and you often risk regrowing tumour cells that are resistant to the chemotherapy,” Williams said. “So that pause in treatment can be a real problem and can also allow a window of time for metastases to grow out.”
“So the other potential advantage of this discovery is that we could take the patient’s blood cell progenitors and treat the patient and allow the continual treatment with chemotherapy.”
Bhatia said it also might be possible to freeze red blood cells and those that produce platelets created from the skin of people with rare blood types, not only for personal use but also for others with the same blood signature who need a transfusion.
The McMaster team also plans to use the cells for testing experimental drugs, in what he calls “a clinical trial in a dish.”
There are, of course, a number of hurdles to overcome: finding a way to produce large quantities of the cells, ensuring their safety and seeking regulatory approval for their use. The team also has to determine the proper recipes for pulling out other cells that make up blood, including key disease-fighting white cells.
Still, Bhatia and his colleagues are already moving ahead — determining what other cellular building blocks of the human body they can draw from skin.
“So we’re hoping this is not just limited to blood,” he said. “We’re hoping we can also get other cell types (and) we already have encouraging evidence.”