New technique for growing cartilage from human embryonic stem cells

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New technique for growing cartilage from human embryonic stem cells

http://www.news-medical.net/?id=29585

Rice University biomedical engineers 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. "

The results are available online and slated to appear in the

September issue of the journal Stem Cells. The study involved cells

from an NIH-sanctioned stem cell line.

Using a series of stimuli, the researchers developed a method of

converting the 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

cartilages 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 said the results are exciting, as they suggest

that similar methods may be used to convert the stem cell-derived

cartilage cells into robust cartilage sections that can be of

clinical usefulness.

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 at Rice University 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 all people, there are many types of " adult " stem cells

at work. Adult stem cells can replace the 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 and, 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 undertaking

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. "