Harvard scientists have managed to
transform one type of pancreas cell in living mice into another – the type of
cell that secrets the hormone insulin, which is destroyed in type 1 diabetes. The
discovery marks a step forward in stem cell research, giving scientists the opportunity
to study the possibility of converting cells of all types into another type
that could replace the cells that are destroyed in some diseases.
Compared to another pioneering method, in
which researchers transform adult cells into embryonic-like stem cells that may
serve as a sort of repair system for the human body, the new technique opens up
the possibility of converting, for example, a bit of heart tissue into cardiac
muscle cells for people who suffered a heard attack and it is faster.
The new method, detailed in the journal
Nature, has been tested only in mice and it combines gene therapy and stem cell
research. “The goal is to create cells that are missing or defective in people.
It’s very exciting,” said Douglas A. Melton, a cell biologist and co-director
of the Harvard Stem Cell Institute, in Cambridge,
Massachusetts, who led the study.
The Harvard scientists called the method “direct
reprogramming.” But the clinical trials in diabetes patients will begin within
two to five years, the researchers said. The advantage is that the biology of
pancreatic development is closely related in mice and humans.
The researchers used three genes of an
ordinary virus in order to transform a common pancreatic cell known as an
exocrine cell into the beta cell that produces insulin. Without the cells that
regulate the level of sugar in patient’s bloodstream, patients are forced to take
insulin and to constantly monitor their blood sugar levels. Type 1 diabetes
affects almost 3 million Americans.
But before they start experiments in
humans, scientists want to find a way to transform cells without using a virus.
The viruses used by Melton’s team are called adenoviruses and they have been
frequently used in gene therapy trials.
The research is the latest in a series of
advances in stem cell research. In previous studies, US scientists managed to
transform skin cells taken from ALS (amyotrophic lateral sclerosis) persons
into the motor neurons, which are exactly the type of cells that degenerate in
patients who suffer from this disease, also known as Lou Gehrig’s disease,
using a cell reprogramming technique. A team of US scientists managed to
produce a library of stem cells, which are called iPS cells and are made using
a technique pioneered by Shinya Yamanaka of Kyoto
University in Japan. The discovery
enables researchers to model thousands of conditions using classical cell
culture techniques, said investigator George Daley.
Compared with the technique which uses
embryonic stem cells, the new method poses “no moral problem,” because the
tissues are no longer obtained by destroying embryos.
The findings were published in the journal
Nature. Stem cell researchers not involved in the study also called the advance
promising. The findings may help researchers in the fight with diabetes and
genetic diseases because it supports the theory that almost any cell in the
body can function as a stem cell and is capable of being reprogrammed into many
different cells in the body.
