AN INJECTION of bone marrow cells could patch up ailing hearts, last week鈥檚
conference heard. Researchers have had promising results with the technique in
mice and pigs.
During a heart attack, muscle cells in the affected area are starved of
oxygen and die. Depending on the extent of the damage, the remaining muscle can
become overstrained and ultimately the heart may fail.
Researchers at Johns Hopkins University and the biotech company Osiris
Therapeutics, both in Baltimore, suspected that stem cells from bone marrow
might be able to repair such damage. Normally, these stem cells give rise to
blood cells, but they are turning out to be rather versatile. Earlier this year,
for example, cultured bone marrow stem cells were persuaded to become
neurons.
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So Mark Pittenger of Osiris and his colleagues injected stem cells from human
bone marrow directly into the hearts of mice that do not reject human cells. To
tell the injected cells apart from mouse cells, the researchers had engineered
them to express a special enzyme.
When Pittenger and his colleagues dissected some of the hearts four days
later, they found that dozens of the human cells had taken up residence in the
heart wall. They all had the characteristic striations of muscle cells and
expressed several proteins only found in heart muscle.
Trials in humans are probably still a few years off, Pittenger says.
Researchers must first make sure that the introduced cells will replace missing
cells in a damaged heart. Parallel experiments with pig marrow cells injected
into pig hearts suggest this should happen.
The replacement cells need not be perfect鈥攐nly safe and at least partly
effective. 鈥淲e鈥檇 like the tissue to be contractile,鈥� Pittenger says. But even if
they鈥檙e not, he thinks they may still do some good. 鈥淚n many cases if you do
nothing the patient will progress to heart failure.鈥�
