'Embryonic-like' stem cells not found
25 July 2013, 08:57
Washington - A US company that promoted its stem cell discovery in
partnership with the Vatican has come under fresh scrutiny by
independent scientists who said on Wednesday the cells do not exist.
at Stanford University said in the journal Stem Cell Reports they could
not replicate NeoStem's findings of very small embryonic-like cells
(VSELs) in the bone marrow of lab mice.
These cells have been
touted by the New York-based company as an ethical alternative to stem
cells requiring the destruction of human embryos, with the same
regenerative ability to transform into other cell types in the body.
Earlier this year, NeoStem announced plans to launch the first human trials of the cells for bone growth.
tried as hard as we could to replicate the original published results
using the methods described and were unable to detect these cells in
either the bone marrow or the blood of laboratory mice," said lead
author Irving Weissman, who directs Stanford's Institute for Stem Cell
Biology and Regenerative Medicine.
Weissman's study is the first
to evaluate the biological potency of the cells, and it found they could
not transform into blood cells and contained very little DNA.
researchers found that what purported to be VSELs - about five
micrometers in diameter - were either debris or dead cells.
true pluripotent cell would be able to differentiate into any tissue
type," said Weissman. "But we couldn't confirm that cells of that size
or phenotype could generate hematopoietic cells with any reliability."
response, NeoStem chair and CEO Robin Smith said the company has
studies in progress that will "confirm whether or not VSEL(s) have
characteristics of a pluripotent stem cell."
"We acknowledge that
there is controversy in the VSEL field but this is not unusual for most
new scientific discoveries and theories [Darwin and evolution,
Copernicus and earth orbiting the sun as examples]," Smith said in a
statement e-mailed to AFP.
The cells were first described in 2006 by researchers working with lab mice at the University of Louisville in Kentucky.
author of that first study to describe VSELs, Mariusz Ratajczak, told
the journal Cell Stem Cell, in the edition coming out 1 August, that he
was anxious about the pace.
"I'm a little bit scared because I
know that NeoStem would like to go fast to the clinic," he was quoted as
saying. "I still think we need to do more basic research."
NeoStem has about 20 patent applications that protect the method for isolating the cells.
company along with other partner institutions have also received $4.5m
in government research grants, including from the Department of Defence
and the National Institutes of Health.
In 2010, it partnered with the Vatican on a charity to promote awareness of alternatives to embryonic stem cell research.
own adult stem cells are the perfect ethical and moral alternative to
stem cells derived from other donors or from embryonic stem cells,"
NeoStem says on its website.
According to Ihor Lemischka,
professor of regenerative biology and director of the Black Family Stem
Cell Institute at The Mount Sinai Medical Centre in New York, the money
spent on VSEL research was a "waste of funding."
"My impression is
that this has been a controversial issue since the VSEL cells were
first described," said Lemischka, who was not involved with the
"It is good that the Weissman laboratory, one of the
most prominent stem cell labs in the world, has addressed these issues,"
he told AFP.
"Optimistically, the issue could now be well on the way to being settled," said Lemischka.