Neurotrophin 3 Shows Promise
in CMT
A pilot study of eight people with Charcot-Marie-Tooth
(CMT) disease, a disorder in which signals in the peripheral
nervous system are impaired, has found that treatment with neurotrophin
3 (NT3) improved sensory function and nerve regeneration.
Neurologist Zarife Sahenk at the Columbus Children’s
Research Institute Neuromuscular Program at Ohio State University
led the study team, which received MDA funding. Jerry Mendell,
a neurologist and MDA clinic co-director at Ohio State University
Hospitals, was also an investigator.
NT3 is a natural substance that belongs to a group of compounds
known as “neurotrophic” (nerve-nourishing) factors.
The investigators, who published their findings online July
6 in Neurology, studied eight people with CMT1A, a form of CMT
that results from an abnormally duplicated PMP22 gene on chromosome
17.
The function of the PMP22 protein, which normally contributes
to an insulating sheath that covers nerves running between muscles
and the spinal cord (peripheral nerves), is disrupted, impairing
sensory (related to temperature, pain, vibration and pressure)
and motor (related to voluntary movement) signals.
After establishing that NT3 was apparently effective in mice
with PMP22 defects, the research team randomly assigned four
adults with CMT1A to receive injections of NT3 three times a
week for six months. Another four people with CMT1A were assigned
to receive an inert substance (placebo) that looked exactly
the same.
At the end of the study, the placebo group’s scores on
a standardized scale of generalized neuropathy-related impairment
had worsened, while scores in the treated group had improved.
There were no significant changes in specific sensory or motor
tests in the placebo group at six months, but the NT3 group
showed improved vibratory sensation assessed by a tuning fork
test. Their reflexes also improved. Motor function did not improve
in either group.
Biopsies of the sural nerve, located in the calf, showed some
regeneration of the nerve tissue in the NT3-treated participants.
“We hope that this approach with neurotrophic agents
can be applied to peripheral neuropathies, where there are few
treatment options,” Sahenk said.
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