Forget the Jetpack - Where Are My Replacement Organs?Welcome to Ask a
Biogeek, a column about cutting-edge biology by UC Berkeley
researcher Terry Johnson.
April 3, 2008
Knowing which organs you can live without is all well and good, but
wouldn't you rather have replacement organs? Tissue engineers already
have some pretty good ones if you happen to lose your skin or
severely damage your bones. And there are some other organs we're
cooking up for you too, as long as you can hold out for a few more
years.
Tissue engineered skin has been used on humans since 2001, though
initially it was merely a replacement for cadaver skin as a temporary
solution for burn patients whose skin was damaged too extensively to
consider skin grafts. More permanent solutions designed to more
closely mimic the structure of skin are on the way, with several
different designs currently under research or in the clinic. We're a
long way from a tissue engineered donor-free face transplant, but
we'll get there. There are non-medical benefits to this work as well -
a variation on tissue engineered skin called Episkin is being
marketed in Europe as an alternative to animal testing of cosmetics.
One of the advantages of skin from an engineer's point of view is
that it's easy to feed. Thin sheets do not require a system of blood
vessels to supply the cells inside the sheet with adequate oxygen and
fuel. Cartilage is another tissue that can do pretty well without a
vasculature, and has a tendency to heal poorly - a combination that
sends clinical researchers off to write grants. If you're looking at
total knee replacement in the future, keep in mind that there's
already one therapeutic alternative and several others in the works.
If you're a sports fan, at one time or another you've probably had
your team's season imperiled by a player's torn ligament. While these
lingering injuries may be a boon to broadcasters and sports writers,
for athletes they can be career-ending events. A biodegradable
polyester combined with cells from undamaged ligament may be the
solution - in rabbit knees, these engineered ligament replacements
already rival transplants. The thing about a transplant is, that
transplant tissue has to come from somewhere. If from another body,
you've got tissue rejection to look forward to. If from you, getting
there requires a scalpel and seriously good painkillers. These
engineered alternatives, using cells from the patient cultured
outside of the body, do a lot less hurting to get to the healing.
Most bone breaks heal on their own with a little immobilization, but
not all, and fractures aren't the only problem one can have with
bone. A man in Finland lost his upper jaw to a tumor, but doctors
were able to create a replacement. A biomaterial scaffold was created
in the shape of the missing part, then seeded with mesenchymal stem
cells from a culture of the cells in a sample of the patient's fat.
The whole device was then implanted in the man's abdomen, where it
was given nine months to develop before being removed and implanted
into the jaw. That may sound a little roundabout, but considering the
only other option was hacking enough bone out of the man's leg to
rebuild the jaw, you can see the attraction. Similar work has been
done in Germany using the patient's back as an incubator instead of
the abdomen, giving you a potential choice of scars as well.
If that same fellow ended up a few teeth shy, or you're worried about
encroaching denturehood, engineered teeth are possible as well - in
mice. Until it's working in humans, I strongly suggest you floss
regularly.
There's a lot of exciting work in kidneys, but if you know any
potential donors try and stay on their good side. There are already a
few tissue engineered bladders engaged in their usual duties inside
patients.
Heart disease is a leading cause of death in the United States, and
to some, the holy grail of tissue engineering. Replacing clogged
blood vessels or valves with healthy engineered tissue would save
lives and wear and tear on the parts of the body where we usually go
scrounging for healthy vessels to replace the damaged bits with. It
doesn't get much tricker than a complete engineered heart transplant -
a machine that requires incredible timing, physical power, a highly
specific vasculature, and most importantly, a vanishingly small
failure rate. One approach is to cheat - that is, take an existing
donor heart and remove all of the cells, leaving the structure
intact. The deheartinated hearts are then seeded with heart cells
from the would-be patient. Rat hearts treated in this manner can be
coaxed into beginning to beat anew, though as of yet not hard enough
to replace an ailing ticker.
Do you have questions you've always wanted to ask a biogeek? You can
email me at tdj@io9.com.
http://io9.com/
organs
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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