July 7, 2022

Reprogramming forges ahead

Scientists use reprogrammed cells to create ALS stem cell line

Developments with
stem cells come so thick and fast nowadays that it’s hard for journalists to
sift footnotes from headlines. Time
magazine described the recent conversion of reprogrammed stem cells into nerve
cells as a “scientific milestone”: “After nearly a decade of setbacks and false
starts, stem-cell science finally seems to be hitting its stride”. This
development, by researchers at Harvard and Columbia Universities, made use of
the induced pluripotent stem cells created by Japanese scientist Shinya
Yamanaka last November. The cells had been taken from patients with ALS
(amyotrophic lateral sclerosis, or Lou Gehrig’s disease) and could someday be
used to create tailor-made cells to treat the debilitating disease.

Was this a
milestone? Probably not. It is just the natural progression for this line of
research. But it is also progress of another kind. Scientists who were formerly
partisans of human embryonic stem cell research are becoming convinced that
this is a cul de sac. As bioethics commentator Wesley J. Smith points out, scientists
have been trying to create stem cell lines for diseased tissue for ten years
using embryonic stem cells. No way. Now, within months of Yamanaka’s discovery,
they have succeeded.

Of course,
reprogrammed cells have their problems, notably a tendency to form tumours
because Yamanaka used viruses to tweak four genes in skins cells which morph
them into cells which behaved like embryonic stem cells. But even this problem
is being overcome. In another development this week, Rudolf Jaenisch and his
team at MIT showed that one of the genes can be tweaked without using viruses.
"This is a good start toward using external cues instead of genetic
manipulation to reprogram cells," says one
of the researchers
. "But we still need to eliminate the need for
retroviruses for the three other genes."

Many stem cell
researchers are still convinced that despite the evident superiority of the
reprogrammed cells, research on human embryonic stem cells – which can only be
done by destroying embryos – is still necessary. “It’s the gold standard for
stem cell research,” is a common explanation. But, as one stem cell scientist
told BioEdge, this is a bit odd. After
ten years of toil across the world, scientists have still not created a human
embryonic stem cell line. How can a non-existent line be a “gold standard”?