D****g
发帖数: 275 | 1 http://www.sciencemag.org/news/2017/11/blood-young-people-does-little-reverse-alzheimer-s-first-test
Blood from young people does little to reverse Alzheimer’s in first test
By Jocelyn KaiserNov. 1, 2017 , 12:40 PM
The first rigorous clinical test of whether blood plasma donated by healthy
young people can help reverse Alzheimer’s disease in older adults has found
that the treatment produced minimal, if any, benefits.
Caregivers for 16 people with mild or moderate Alzheimer’s disease reported
that their charges performed slightly better at daily tasks after receiving
weekly injections of young plasma, according to the abstract of a talk to
be presented on Saturday at the 10th Clinical Trials on Alzheimer’s Disease
meeting in Boston. But the patients did no better on cognitive tests
administered by researchers—a crucial standard for whether the treatment
had a significant impact. All the same, the sponsor of the trial—startup
company Alkahest in San Carlos, California, is “encouraged” to run more
trials, says CEO Karoly Nikolich.
The notion that young blood may have antiaging or other beneficial
properties comes from 150-year-old experiments that stitched together the
skins of two still-living old and young mice, allowing their circulation to
be shared. Researchers who recently revived the technique have reported that
this so-called parabiosis revitalizes the liver, muscles, and brain of the
old mice. They are now hunting for molecules within young blood that may
explain these apparent antiaging effects.
Three years ago, neuroscientist Tony Wyss-Coray’s lab at Stanford
University in Palo Alto, California, found that injections of the plasma
portion of blood from young mice could achieve the same antiaging effects as
parabiosis in old mice. And his group reported last year that injections of
young mouse plasma improved cognitive function in mice with a form of
Alzheimer’s.
To test whether young plasma could similarly help people with Alzheimer’s,
Alkahest—which Wyss-Coray co-founded—sponsored a small trial led by
Stanford neurologist Sharon Sha. Nine patients with mild to moderate
Alzheimer’s got four once-weekly infusions of either saline (as a placebo)
or plasma from 18- to 30-year-old male donors. After a 6-week break, the
infusions were switched so that the patients who had gotten plasma got
saline, and the patients who had gotten saline received plasma. Another nine
patients received young plasma only, and no placebo. Two patients dropped
out of the trial, one after developing a rash from an infusion and another
who had an unrelated stroke.
After receiving young plasma, the 16 remaining patients performed no better
on objective cognitive tests given by medical staff. However, on average
their scores improved slightly—4.5 points on a 30-point scale—on a
caregiver survey about whether they needed help with daily activities such
as making a meal or traveling. The patients’ scores also improved modestly
on another survey that asks caregivers how well patients can perform simple
tasks like getting dressed and shopping.
Non–Alkahast affiliated Alzheimer’s researchers who have read the abstract
are intrigued but cautious. Howard Feldman of the University of California,
San Diego, calls the results “interesting,” but adds that the study
raises many questions, such as what cellular process in the brain the
treatment is targeting.
That’s what neuroscientist Zaven Khachaturian, who retired from the
National Institute on Aging in Bethesda, Maryland, and is now a scientific
advisor to the Alzheimer’s Association, wants to know. “They need to
explain the potential mode of action,” he says. He wants to keep an “open
mind,” but adds that the positive effects reported by the caregivers could
merely be a placebo effect: “[Patients] could feel better because somebody
paid attention to them.”
Wyss-Coray agrees that not much can be concluded from the small trial, but
says, “It’s tempting to feel hopeful about the improvement in functional
scores.” Because the treatment seemed safe, Alkahest now wants to launch
another trial that will use just the fraction of the blood plasma that
contains growth factors, but not coagulation factors and other components
that may do more harm than good. In animals, this plasma fraction was more
effective at improving cognition in the mice with an Alzheimer’s-like
condition than whole plasma, Wyss-Coray says. Alkahest also wants to test a
range of doses and include patients with more severe Alzheimer’s.
Resolving whether young plasma works has recently taken on an increased
urgency, as a private clinic in California is already offering plasma
infusions for people, sick or healthy, willing to pay $8000 for a 2-day
young plasma treatment. That treatment has been characterized by the company
as a “clinical trial,” but researchers have criticized the effort as
unscientific. |
|
