IT鈥橲 no good transplanting organs if they鈥檙e not up to the job. So
bioengineers who are culturing muscle tissues in the lab have resorted to giving
their creations a regular work-out.
The shortage of tissue and organs for transplants could be solved by building
replacements in the lab. However, creating tissue with the right properties is
difficult. After being transplanted, it may adapt to the body鈥檚 demands. 鈥淏ut
there鈥檚 no reason we can鈥檛 do some of that remodelling prior to implanting it,鈥�
says Robert Nerem of the Georgia Institute of Technology in Atlanta. He has
demonstrated his point with artificial blood vessels constructed by growing
smooth muscle cells in a tubular mould and then slipping it over an inflatable
piece of silicon. Initially, the vessels were not strong enough. Maximum blood
pressure is about 192 millimetres of mercury during exercise鈥攂ut the
lab-grown vessels ruptured at 150 millimetres.
So Nerem鈥檚 team 鈥渆xercised鈥� the vessels, forcing pressurised air through them
every second for up to 8 days. The resulting denser packing of cells could
withstand pressures up to 300 millimetres of mercury鈥攕trong enough to
replace veins. However, they may not yet be tough enough to replace arteries,
where blood pressure is higher.
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