快猫短视频

FOR people with malignant brain tumours, the prospects are often bleak. The
tumours resist drugs and radiotherapy, and are difficult to remove surgically
because they tend to be widely spread. But help could one day come from neural
stem cells鈥攑rimitive cells that can develop into other types of brain
cells.

Gaetano Finocchiaro and his colleagues at the Carlo Besta National
Neurological Institute in Milan knew from earlier studies that neural stem cells
can spread throughout the brain once they have been injected into it. So they
decided to test whether these cells could be used to transport anticancer agents
into tumours.

The researchers genetically engineered rat and mouse neural stem cells to
produce interleukin-4, a chemical that encourages the immune system to attack
cancer cells. When they injected the cells into rats and mice with malignant
brain tumours, the animals survived significantly longer than untreated animals.
Magnetic resonance imaging showed that the larger tumours had become
smaller.

鈥淚t鈥檚 a cool study. It raises lots of exciting possibilities for using neural
stem cells to deliver therapeutic agents to disseminating brain tumours,鈥� says
Thor Ostenfeld of the Centre for Brain Repair at Cambridge University. Viruses
have previously been used to shuttle the gene for interleukin-4 into the
rodents鈥� brains, and this too improved the animals鈥� survival. However, viruses
are short-lived and cannot infiltrate the brain easily.

The Italian researchers were surprised to discover that their rodents lived
longer than untreated animals even if they were given stem cells that had not
been engineered to secrete interleukin-4. They found that the cells secrete
another, unknown substance that slows the division of cancer cells. 鈥淲e need to
find out what factor is being released by the cells to stop proliferation,鈥� says
Finocchiaro.

Being able to treat rodents with brain tumours does not necessarily translate
into a treatment for people, however. The human brain is larger, Finocchiaro
points out, so cells would have to migrate further. What鈥檚 more, the brain
tumours the team studied are far less diffuse than many malignant human brain
tumours.

In a separate development, Mark Noble of the Huntsman Cancer Institute in
Salt Lake City suggests that neural stem cells could help people with brain
tumours by repairing the brain damage caused by chemotherapy and radiotherapy.
鈥淚t鈥檚 an absolutely horrific problem,鈥� Noble says.

Animals studies have shown
that neural stem cells can repair damage to the central nervous system such as
spinal cord lesions and the destruction of myelin, an insulating tissue around
nerve fibres
(快猫短视频, 6 February1999,p 23).
Noble suggests that
stem cells be tested for their ability to repair brain damage in cancer
patients. 鈥淭his could be the bone marrow transplant of the future,鈥� he says.