Tuesday, August 17, 2004

Best kept far from the cafeteria

Careful With That Petri Dish (Wired News - Lakshmi Sandhana - 16 Aug 2004)

Two British researchers are planning to help NASA grow replacement human tissue that astronauts can transplant into their bodies if necessary on their way to Mars. ...

Using NASA's microgravity facilities, the duo hope to develop preventive medicines that the astronauts can take with them to guard against bone-mass loss caused by long-term space exposure. The researchers are also looking for ways to boost the astronauts' own defense mechanisms against space radiation.

"It's about using the body's natural defense system," said Forraz. "Some of your cells are even now becoming cancerous, and the first line of defense against cancer is natural killer cells within the body that detect these mutants and kill them straight away. One of the main limitations to long space travel is space radiation, and we plan to enhance the natural killer cells in astronauts to tackle the damages."

If the astronauts' immunity to radiation cannot be significantly enhanced, then the next step, according to the team, is to grow replacement tissue. They'll begin their research by combining umbilical blood and bone-marrow stem cells with tissues from adults to grow new body tissue in a zero-microgravity environment that mimics conditions in the womb.

"We plan to use adult stem cells derived from the astronauts' blood

Hallelujah! So far they're not lunging at the weakest; they're avoiding the better source; they're using adult stme cells, not fetal stem cells.

and to put that in a zero-G-microgravity-simulating bioreactor," said McGuckin. "Using the right cocktail of stimuli, we can instruct the cells to grow into not only blood, but also the liver or part of the muscles, for example, to regenerate the damaged tissue. The long-term goal would be (to be) able to take those bioreactors on a space flight to regenerate tissue for the astronauts."

Growing body parts on demand has been the Holy Grail of tissue engineering experts all around the world. The main challenge so far has been growing tissue in three dimensions. Because of gravity's effects, cells grown in a flat dish have a sheet-like appearance, behave like individual cells and fail to form the associations that lead to the growth of tissues or organs.

A microgravity environment, however, has distinct advantages -- a bioreactor can mimic weightlessness, allowing the cells to form three-dimensional structures similar to tissues found in the human body.

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