[tt] eurekalert: hESCs => cartilage tissue

[Alejandro Dubrovsky]

(
http://www.media.rice.edu/media/NewsBot.asp?MODE=VIEW&ID=9935
)

09/05/2007

Embryonic stem cells used to grow cartilage
Rice method is first to yield cartilage-like cells, engineer human
cartilage

BY JADE BOYD
Rice News Staff

Rice bioengineers have developed a new technique for growing cartilage
from human embryonic stem cells, a method that could be used to grow
replacement cartilage for the surgical repair of knee, jaw, hip and
other joints.

"Because native cartilage is unable to heal itself, researchers have
long looked for ways to grow replacement cartilage in the lab that could
be used to surgically repair injuries," said lead researcher Kyriacos A.
Athanasiou, the Karl F. Hasselmann Professor of Bioengineering. "This
research offers a novel approach for producing cartilage-like cells from
embryonic stem cells, and it also presents the first method to use such
cells to engineer cartilage tissue with significant functional
properties."

 KYRIACOS athanasiou, gwen hoben and eugene koay
KYRIACOS ATHANASIOU, GWEN HOBEN and EUGENE KOAY
The results are available online and slated to appear in the September
issue of the journal Stem Cells. The study involved cells from a stem
cell line sanctioned by the National Institutes of Health.

Using a series of stimuli, the researchers developed a method to convert
stem cells into cartilage cells. Building upon this work, the
researchers then developed a process for using the cartilage cells to
make cartilage tissue.

The results show that cartilage can be generated that mimic the
different types of cartilage found in the human body, such as hyaline
articular cartilage -- the type of cartilage found in all joints -- and
fibrocartilage -- a type found in the knee meniscus and the jaw joint.
Athanasiou finds the results exciting, since they suggestthat similar
methods may be used to convert the stem cell-derived cartilage cells
into robust cartilage sections that can be used clinically.

Tissue engineers, like those in Athanasiou's research group, are
attempting to unlock the secrets of the human body's regenerative system
to find new ways of growing replacement tissues like muscle, skin, bone
and cartilage. Athanasiou's Musculoskeletal Bioengineering Laboratory
specializes in growing cartilage tissues.

The idea behind using stem cells for tissue engineering is that these
primordial cells have the ability to become more than one type of cell.
In the human body, many types of "adult" stem cells are at work. Adult
stem cells can replace blood, bone, skin and other tissues in the body.
Stem cells become specific cells based upon a complex series of chemical
and biomechanical cues, signals that scientists are just now starting to
understand.

Unlike adult stem cells, which can become only a limited number of cell
types, embryonic stem cells can theoretically become any type of cell in
the human body.

Athanasiou's group has been one of the most successful in the world at
studying cartilage cells, especially engineering cartilage tissues. He
said that for his research the primary advantage that embryonic stem
cells have over adult stem cells is their ability to remain malleable.

"Identifying a readily available cell source has been a major obstacle
in cartilage engineering," Athanasiou said. "We know how to convert
adult stem cells into cartilage-like cells. The more problematic issue
comes in trying to maintain a ready stock of adult stem cells to work
with. These cells have a strong tendency to convert from stem cells into
a more specific type of cell, so the clock is always ticking when we
work with them."

By contrast, Athanasiou said his research group has found it easier to
grow and maintain a stock of embryonic stem cells. Nonetheless, he is
quick to point out that there is no clear choice about which type of
stem cell works best for cartilage engineering.

"We don't know the answer to that," Athanasiou said. "It's extremely
important that we study all potential cell candidates, and then compare
and contrast those studies to find out which works best and under what
conditions. Keep in mind that these processes are very complicated, so
it may well be that different types of cells work best in different
situations."

Athanasiou began studying embryonic stem cells in 2005. Since funding
for the program was limited, he asked two new graduate students in his
group if they were interested in pursuing the work as a secondary
project to their primary research. Those students, Eugene Koay and Gwen
Hoben, are co-authors of the newly published study. Both are enrolled in
the Baylor College of Medicine Medical Scientist Training Program, a
joint program that allows students to concurrently earn their medical
degree from Baylor while pursuing Ph.D. studies at Rice.

"Eugene and Gwen are both outstanding students," Athanasiou said. "Each
earned their undergraduate degree from Rice and each worked in my
laboratory as undergraduate students. They have chosen to do this
research because they think this may represent the future of
regenerative medicine."