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Teknologi stem cell poin untuk
indikator awal skizofrenia
Stem cell technology points to early indicators of schizophrenia
Date:
May 13, 2014
Source:
Salk Institute for Biological
Studies
Summary:
Using new stem cell technology, scientists have shown
that neurons generated from the skin cells of people with schizophrenia behave
strangely in early developmental stages, providing a hint as to ways to detect
and potentially treat the disease early. "This study aims to investigate
the earliest detectable changes in the brain that lead to schizophrenia,"
says one researcher. "We were surprised at how early in the developmental
process that defects in neural function could be detected."
.............................
Using new stem cell technology, scientists at the Salk
Institute have shown that neurons generated from the skin cells of people with
schizophrenia behave strangely in early developmental stages, providing a hint
as to ways to detect and potentially treat the disease early.
The findings
of the study, published online in April's Molecular Psychiatry, support
the theory that the neurological dysfunction that eventually causes
schizophrenia may begin in the brains of babies still in the womb.
"This
study aims to investigate the earliest detectable changes in the brain that
lead to schizophrenia," says Fred H. Gage, Salk professor of genetics.
"We were surprised at how early in the developmental process that defects
in neural function could be detected."
Currently,
over 1.1 percent of the world's population has schizophrenia, with an estimated
three million cases in the United States alone. The economic cost is high: in
2002, Americans spent nearly $63 billion on treatment and managing disability.
The emotional cost is higher still: 10 percent of those with schizophrenia are
driven to commit suicide by the burden of coping with the disease.
Although
schizophrenia is a devastating disease, scientists still know very little about
its underlying causes, and it is still unknown which cells in the brain are
affected and how. Previously, scientists had only been able to study
schizophrenia by examining the brains of patients after death, but age, stress,
medication or drug abuse had often altered or damaged the brains of these
patients, making it difficult to pinpoint the disease's origins.
The Salk
scientists were able to avoid this hurdle by using stem cell technologies. They
took skin cells from patients, coaxed the cells to revert back to an earlier
stem cell form and then prompted them to grow into very early-stage neurons
(dubbed neural progenitor cells or NPCs). These NPCs are similar to the cells
in the brain of a developing fetus.
The
researchers generated NPCs from the skin cells of four patients with
schizophrenia and six people without the disease. They tested the cells in two
types of assays: in one test, they looked at how far the cells moved and
interacted with particular surfaces; in the other test, they looked at stress
in the cells by imaging mitochondria, which are tiny organelles that generate
energy for the cells.
On both
tests, the Salk team found that NPCs from people with schizophrenia differed in
significant ways from those taken from unaffected people.
In
particular, cells predisposed to schizophrenia showed unusual activity in two
major classes of proteins: those involved in adhesion and connectivity, and
those involved in oxidative stress. Neural cells from patients with
schizophrenia tended to have aberrant migration (which may result in the poor
connectivity seen later in the brain) and increased levels of oxidative stress
(which can lead to cell death).
These
findings are consistent with a prevailing theory that events occurring during
pregnancy can contribute to schizophrenia, even though the disease doesn't
manifest until early adulthood. Past studies suggest that mothers who
experience infection, malnutrition or extreme stress during pregnancy are at a
higher risk of having children with schizophrenia. The reason for this is
unknown, but both genetic and environmental factors likely play a role.
"The
study hints that there may be opportunities to create diagnostic tests for
schizophrenia at an early stage," says Gage, who holds the Vi and John
Adler Chair for Research on Age-Related Neurodegenerative Disease.
Kristen
Brennand, the first author of the paper and assistant professor at Icahn School
of Medicine at Mount Sinai, said the researchers were surprised that the
skin-derived neurons remained in such an early stage of development. "We
realized they weren't mature neurons but only as old as neurons in the first
trimester," Brennand says. "So we weren't studying schizophrenia but
the things that go wrong a long time before patients actually get sick."
Interestingly,
the study also found that antipsychotic medication such as clozapine and
loxapine did not improve migration in NPCs (in particular, loxapine actually
worsened migration in these cells).
"That
was an experiment that gave the opposite results from what we were
expecting," says Brennand. "Though in hindsight, using drugs that
treat symptoms might not be helpful in trying to prevent the disease."
The next
steps to this work will be to increase the sample size to a broader range of
patients and to look at hundreds or thousands of patient samples, says
Brennand.
Story
Source:
The above
story is based on materials provided by Salk Institute for Biological Studies. Note:
Materials may be edited for content and length.
Journal
Reference:
- K Brennand, J N Savas, Y Kim, N Tran, A Simone, K Hashimoto-Torii, K G Beaumont, H J Kim, A Topol, I Ladran, M Abdelrahim, B Matikainen-Ankney, S-h Chao, M Mrksich, P Rakic, G Fang, B Zhang, J R Yates, F H Gage. Phenotypic differences in hiPSC NPCs derived from patients with schizophrenia. Molecular Psychiatry, 2014; DOI: 10.1038/mp.2014.22
Cite This
Page:
Salk Institute for Biological
Studies. "Stem cell technology points to early indicators of
schizophrenia." ScienceDaily. ScienceDaily, 13 May 2014.
<www.sciencedaily.com/releases/2014/05/140513142032.htm>.
