A WOMAN in Pittsburgh has been injected with human neural tissue grown in the
lab to repair brain damage caused by a stroke. If her pioneering operation is a
success, the same method could be tried on other disorders such as Parkinson鈥檚
disease and spinal cord injuries.
In the past, a few such transplants have been performed on Parkinson鈥檚
patients using fetal tissue
(鈥淏rain repair kit鈥�, 快猫短视频, 21 March, p 40),
but they have never been tried with stroke victims, and never
using cultured cells. Cultured neurons could eventually provide a endless supply
of tissue, eliminating the practical and ethical problems of taking brain cells
from aborted fetuses.
Doctors injected around 2 million cultured nerve cells into the brain of a
62-year-old woman who has been unable to speak or move her right arm or leg
since a stroke last September. Over a fifth of stroke victims suffer severe and
permanent disabilities because parts of their brains have died from lack of
blood.
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The neurons were injected with a syringe through three tiny holes drilled in
the patient鈥檚 skull, and should link up with the live neurons surrounding the
dead tissue. Researchers have already shown that the motor and learning skills
of rats that have suffered strokes improve if they are given human neuron
transplants.
The operation, which was performed on 23 June, is the first of 12 approved by
the US Food and Drug Administration, and larger trials will follow if it is
successful. 鈥淭his is what we鈥檝e been waiting for,鈥� says Douglas Kondziolka of
the University of Pittsburgh in Pennsylvania, the neurosurgeon who led the
project. 鈥淥ver a matter of months, hopefully we will see improvement.鈥�
Twenty-four weeks after the operation, researchers plan to measure the
implanted neurons鈥� activity using positron emission tomography. They will also
look for changes in the patient鈥檚 ability to move and talk.
The transplanted neurons came from a cell line established a decade ago, when
cells were taken from a patient with a rare testicular tumour containing
embryonic cells. These cells have the potential to specialise and form many
types of tissue, and researchers were able to isolate embryonic nerve cells.
When transplanted into rodent brains, they took on the appearance and function
of nearby neurons.
The nerve cells, grown by a company called Layton BioSciences in Atherton,
California, can be frozen and thawed just before a brain operation. They are
treated with drugs that prevent cell division and the possibility of cancer.
Large enough quantities could be produced to treat millions of stroke
survivors.
Lab cultures offer enormous advantages over other sources of neurons, such as
tissue from human fetuses, which cannot be frozen in storage then thawed. 鈥淓ven
if you get away from the ethics issue, procurement of the tissue鈥攇etting
it from abortion clinics鈥攊s difficult,鈥� comments Paul Sanberg, who runs a
fetal tissue transplant trial to treat Parkinson鈥檚 disease at the University of
South Florida in Tampa.
Other researchers have proposed using neural tissue from pigs, but this
raises concerns about cross-species disease transmission. And animal tissue
might provoke a strong immune response, causing rejection. Although the cultured
human neurons may also produce an immune response, it will hopefully be small
enough to control safely with immunosuppressive drugs.