What is Stem Cell: [StemCells] New way to grow hES

UC Riverside researcher develops novel method to grow human embryonic
stem cells
Published: Tuesday, August 19, 2008 - 21:42 in Biology & Nature

The majority of researchers working with human embryonic stem cells
(hESCs) – cells which produce any type of specialized adult cells in
the human body – use animal-based materials for culturing the cells.
But because these materials are animal-based, they could transmit
viruses and other pathogens to the hESCs, making the cells unsuitable
for medical use. Now, a stem-cell scientist at UC Riverside has
devised a method of growing hESCs in the lab that uses no animal-
derived materials – an important advance in the use of hESCs for
future medical purposes.

Because of their tremendous potential, hESCs are considered promising
sources for future cell therapy to treat diseases such as Parkinson's
disease and diabetes mellitus.

Noboru Sato, an assistant professor of biochemistry, developed the
new method, which is not only cleaner and easier to use than
conventional methods of culturing hESCs but also results in hESCs
whose pluripotency – the potential to differentiate into any of the
specialized cells of the body such as neurons, cardiac muscles, and
insulin-producing cells – is uncompromised.

Currently in labs worldwide, many researchers grow hESCs on Matrigel-
coated culture plates, Matrigel being the trade name for a gelatinous
extract, taken from mouse tumor cells, that contains extracellular
matrices (ECMs), made up of special proteins. The Matrigel coating
provides the scaffolding to which the hESCs first attach and then
grow in undifferentiated colonies before differentiating into
specialized cells.

"The development of animal-free coating methods for hESCs still
remains a major challenge due to the complexity of ECMs and
insufficient knowledge about how hESCs control cell-cell and cell-ECM
interactions," explained Sato, who led the research project.

His lab identified a specific signaling pathway, called Rho-Rock,
which the hESCs use during colony formation and which plays an
important role in physical interactions between hESCs. When the
researchers blocked the pathway, they found, as expected, that the
normal colony formation of hESCs was considerably impaired. They also
found that the hESCs maintained their pluripotency.

"Until now, it was generally assumed that the hESC colony formation
was pivotal for maintaining pluripotency," Sato said. "But we show
that pluripotency can be retained independent of close cell-cell
contact."

Prue Talbot, the director of UCR's Stem Cell Center of which Sato is
a member, noted that Sato's discovery could affect the way embryonic
stem cells are grown in the future.

"His work is certainly an important step forward in both
understanding signal transduction pathways in stem cells and in the
development of an improved methodology for culturing stem cells," she
said.

Study results appear online in the Aug. 20 issue of the Public
Library of Science (PLoS) ONE.

In the study, Sato's group extensively screened various types of
scaffold materials in combination with Y27632, a chemical compound
that blocks the Rho-Rock pathway, and found that the Matrigel coating
could be replaced with "poly-D-lysine," a chemically synthesized ECM.
The major advantages of poly-D-lysine over Matrigel are that poly-D-
lysine is completely animal-free, easy to handle, and its quality is
consistent.

"We found that the growth of the hESCs under this novel culture
condition was almost identical to the growth of hESCs on Matrigel-
coated culture plates, with no compromise in pluripotency," Sato
said.

Having started his career as a physician in Japan, Sato began
researching stem cell biology as a research fellow at The Rockefeller
University, NY, one of the foremost research centers in the world. He
accepted a faculty position in the Department of Biochemistry at UCR
in 2006. He was joined in the research project by Nicole Harb of UCR
and Trevor K. Archer of the National Institute of Environmental
Health Sciences (NIEHS), NC.

The research was a collaboration between UCR and NIEHS, and funded by
UCR start-up funds to Sato and a grant to Archer from the National
Institutes of Health.

"Our research goal is to understand the basic mechanisms underlying
unique biological functions of pluripotent stem cells, and to
translate the obtained knowledge into future medical applications,"
Sato said.

His group is now focusing on applying his technique to the latest
stem cell technology, "induced pluripotent stem (iPS) cells," which
are pluripotent stem cells artificially derived from adult cells
without using embryos. "Our next step is to produce new animal-free
iPS cell lines," Sato said.

UCR's Office of Technology Commercialization has applied for a patent
on Sato's discovery and is looking for industrial partners interested
in further developing it.

Source: University of California - Riverside

http://esciencenews.com/articles/2008/08/19/uc.riverside.researcher.de
velops.novel.method.grow.human.embryonic.stem.cells

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