IPSCs were first created in humans only about 10 1/2 months ago. Yet, hurdles to their full use in regenerative medicine fall at a rate not seen with ESCR or, for sure, therapeutic cloning. And now another one. From the story:
Scientists are reporting today that they have overcome a major obstacle to using a promising alternative to embryonic stem cells, bolstering the prospects for bypassing the political and ethical tempest that has embroiled hopes for a new generation of medical treatments.
The researchers said they found a safe way to coax adult cells to regress into an embryonic state, alleviating what had been the most worrisome uncertainty about developing the cells into potential cures. “We have removed a major roadblock for translating this into a clinical setting,” said Konrad Hochedlinger, a Harvard University stem cell researcher whose research was published online today by the journal Science. “I think it’s an important advance.”
So what was the big breakthrough?
Scientists last year shook up the scientific and political landscape by discovering how to manipulate the genes of adult cells to revert them into the equivalent of embryonic cells–entities dubbed “induced pluripotent stem” or “iPS” cells — which could then be transformed into any type of cell in the body. Subsequent work has found that the cells can alleviate symptoms of Parkinson’s disease and sickle cell anemia in mice.
But the first iPS cells were created by ferrying four genes into the DNA of adult cells using retroviruses, which can cause cancer in animals. There was also concern because the viruses integrated their genes into the cells’ DNA in the course of transforming them. In the new work, Hochedlinger and his colleagues used a different type of virus, known as an adenovirus, which does not integrate its genes into a cell’s DNA and therefore is believed to be harmless, to ferry the same four transformative genes into the DNA of mouse skin and liver cells.
“The adenovirus will infect the cells but then will clear themselves from the cells. After a few cell divisions there are no traces of the virus in the cell,” he said. “You can’t tell the virus was ever there.”
This does not resolve the problem with all pluripotent cells, e.g., they cause teratomas–a different tumor issue than the cancer fear with IPSCs that seems to have been overcome. But boy, is this field moving fast.