- New cyanine compound developed by
scientists can be used to accurately screen for Alzheimer's disease, as
well as an imaging agent
- Compound has low toxicity and may
also have therapeutic potential in Alzheimer's disease
- Alzheimer's disease is a common
neurodegenerative disorder with no cure and current diagnostic methods may
not be very effective and not entirely safe.
Newly discovered cyanine compounds found
to have multiple uses as screening and imaging agents as well as with possible
therapeutic potential. The compound has been invented by scientists at the Hong
Kong Baptist University (HKBU) Chemistry. The invention has received four US
patents as well as a patent by the Chinese government.
The research team was headed jointly by
Professor Ricky Wong Man-shing and Associate Professor Dr Li Hung-wing with
faculty from the Department of Chemistry of HKBU.
Compounds as Screening Agent
Cyanine occurs in nature in blueberries,
and the cyanine compounds employed by the team have been particularly suitable
to detect amyloid.
- The proteins beta amyloid peptide,
tau, and p-tau, in human's cerebrospinal fluid have been linked to Alzheimer's disease
- The proprietary cyanine compounds
have been shown to accurately quantify these proteins when applied on a
nanodetection screening test described below
- The screening test can be done on
body fluids such as saliva, serum, and urine taking only very small
amounts (few microliters). Normally, the protein is measured in the
cerebrospinal fluid which is obtained by inserting a needle into the
spinal cord, which is more risky.
- It is accurate, rapid, low cost and
ultrasensitive in nature compared to existing tests
The Alzheimer's protein (antigen) present
in the body fluids will react with the corresponding antibody incorporated on
the surface of magnetic nanoparticles. To this mixture the cyanine compound is
added. If the protein is present, there will be enhancement of fluorescent
signal which can be quantified on an ultraviolet imaging system.
‘Cyanine compounds shown to accurately detect Alzheimer’s disease associated protein in body fluids, can be used as imaging agent to monitor disease progression and may also have possible therapeutic properties’
Says Dr Li, "This newly developed
assay will be particularly useful as a low-cost
diagnostic and prognostic tool for Alzheimer's
. It can also serve as a novel
alternative non-invasive tool for population-wide screening
disease. This scientific detection assay has a high potential to serve as a
practical diagnosis tool."
However, Li adds that
the amounts of the protein in serum, urine and saliva is much lower than CSF,
making detection more difficult.
The findings of the study titled
"Ultra-sensitive detection of protein biomarkers for diagnosis of
Alzheimer's disease" has appeared in the internationally respected
academic journal Chemical Science
Compounds as Imaging Agents
Interestingly, in yet another study, the
team found one type of cyanine compound
can specifically bind to short chains of beta-amyloid peptides (oligomers) and
this binding results in enhancement of the fluorescent signal.
This unique property of cyanine compound
can be applied to MRI and/or fluorescence imaging to detect beta-amyloid
in the patient and to
monitor disease status
It is these beta amyloid oligomers
in the form of fibrils and senile plaques
that are most neurotoxic and important
in the pathogenesis
of disease, making it all the more important to be able
to detect them accurately than any other form of beta amyloid.
The cyanine compound has in fact been successfully applied to detect and image
beta-amyloid oligomers in Alzheimer's disease
transgenic mice models where
the disease-like pathology has just started to evolve.
Compounds as Potential Treatment Option
It has also been shown that this newly
created compound can cross the blood brain barrier, and is capable of preventing beta amyloid monomers from aggregating and
forming neurotoxic oligomers
and thus has a neuroprotective effect. In
addition the compound displays low toxicity and its properties therefore show
promise as a treatment option in Alzheimer's disease that need to be further
In fact the study team is currently
looking at the neuroprotective effects of this compound on cognitive
improvement in mouse model of Alzheimer's disease.
Should future studies planned establish
the efficacy of cyanine compounds in detecting, imaging and treatment of
Alzheimer's disease, it is indeed good news for patients and their families and
doctors treating the disease.
- Yinhui Li, Di Xu, Anyang Sun, et
al. Fluoro-substituted cyanine for reliable in vivo labelling of amyloid-β
oligomers and neuroprotection against amyloid-β induced toxicity.Chemical