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Frontiers
Replacement Parts: Creating Artificial Tissues and Organs That Work
November 1996
Move over Robocop, human bodies do better with
stimulated cell growth and a stronger understanding of biochemistry.
According to Bob Langer of MIT, the next generation of "artificial" organs
will be custom-grown body parts, which, in the end, won't have much
that's artificial at all.
NSF-funded Langer and his Harvard colleague Jay Vacanti start these in
vitro organs by using computer-aided designs to create plastic
versions of skin, cartilage, and internal organs. The polymer model
provides a scaffolding. Seed cells are expected to attach to the
plastic and grow. Once the cells have covered the scaffolding, the
polymer degrades into carbon dioxide and water.
So far, several biomedical companies have used the team's general
techniques to create artificial skin and other tissues. These products
are in clinical trial, says Langer, and will be distributed within
10 years.
In addition, Langer and Vacanti say, growing more complicated organs
isn't as far-fetched as it might seem.
"This [scaffolding] approach
is based on the following observations," they write in the journal Science, "i)
Every tissue undergoes remodeling; ii) Isolated cells tend to reform
the appropriate tissue structure under experimental conditions."
In other words, body parts are constantly being rejuvenated by new
cells. And given the correct signals, cells will switch jobs as needed.
With skin, the system is working. Other tissues and organs should follow,
the researchers write.
While these projects come to fruition, researchers at NSF's newest
Engineering Research Center, the University of Washington Engineering
Biomaterials (UWEB ) center, are developing a new generation of biomaterials
that "talk" to tissue and actively induce healing.
Even though the current generation of medical devices and biomaterials
saves and improves the quality of millions of lives, there is room
for improvement.
The body does not recognize the molecules that make up plastic, metal,
and ceramic implants. And so it isolates these implants, walling them
off with scar tissue. The implants--such as glucose sensors or blood
vessel replacements--never work as well as they might with normal healing.
Started September 1996, UWEB is headed by bioengineer Buddy Ratner,
includes researchers from a wide range of disciplines, and has the
corporate support of 3M, Baxter Healthcare, Dow Corning, and others.
The center's approach is to study healing at different levels--from
the macro animal models, to the micro, sub-cellular chemistry, explains
bioengineer Joan Sanders, leader of the medical applications group.
For example, her group is studying the biochemical signals bodies
send out to heal wounds. If implants were designed to encourage cells
to send out those signals, potentially the body would "heal" the implant
rather than wall it off. "We're getting the cells to do the work for
us," she says.
UWEB researchers hope to begin animal trials of the first materials
in about three years.
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