Failed experiment helps patients
2008-05-07 12:29
Bethesda - An experiment that went
wrong may provide a new way to treat multiple sclerosis, a
Canadian researcher said on Tuesday.
Patients who got bone marrow stem cell transplants -
similar to those given to leukaemia patients - have enjoyed a
mysterious remission of their disease.
And Dr Mark Freedman of the University of Ottawa is not
sure why.
"Not a single patient, and it's almost seven years, has
ever had a relapse," Freedman said.
Multiple sclerosis or MS affects an estimated one million
people globally. There is no cure.
It can cause mild illness in some people while causing
permanent disability in others. Symptoms may include numbness
or weakness in one or more limbs, partial or complete loss of
vision, and an unsteady gait.
Freedman, who specialises in treating MS, wanted to study
how the disease unfolds. He set up an experiment in which
doctors destroyed the bone marrow and thus the immune systems
of MS patients.
Then stem cells known as haematopoietic stem cells,
blood-forming cells taken from the bone marrow, were
transplanted back into the patients.
"We weren't looking for improvement," Freedman told a stem
cell seminar at the US National Institutes of Health.
"The actual study was to reboot the immune system."
Once MS is diagnosed, Freedman said, "you've already missed
the boat. We figured we would reboot the immune system and
watch the disease evolve. It failed."
Stem cell repair
They had thought that destroying the bone marrow would
improve symptoms within a year. After all, MS is believed to be
an autoimmune disease, in which immune system cells mistakenly
attack the fatty myelin sheath that protects nerve strands.
Patients lose the ability to move as the thin strands that
connect one nerve cell to another wither.
Instead, improvements began two years after treatment.
Freedman reported to the seminar about 17 of the patients
he has given the transplants to.
"We have yet to get the disease to restart," he said.
Patients are not developing some of the characteristic brain
lesions seen in MS. "But we are seeing this repair."
MS patients often have hard-to-predict changes in their
symptoms and disease course, so Freedman says his team must
study the patients longer before they can say precisely what is
going on.
"We are trying to find out what is happening and what could
possibly be the source of repair," Freedman said.
But he has found some hints that may help doctors who treat
MS by using drugs to suppress the immune system.
"Those with a lot of inflammation going on were the most
likely to benefit (from the treatment)," he said.
"We need some degree of inflammation." While inflammation
may be the process that destroys myelin, it could be that the
body needs some inflammation to make repairs, Freedman said.
Immune cells secrete compounds known as cytokines. While
these are linked with inflammation, they may also direct cells,
perhaps even the stem cells, to regenerate.
The treatment itself is dangerous - one patient died when
the chemicals used to destroy his bone marrow also badly
damaged his liver.