Professor Andrew Hill and Dr Lesley Cheng, together with collaborators at CSIRO Australia and the Australian Imaging, Lifestyle and Biomarker Group, are working to develop a blood test for Alzheimer’s disease (AD); scanning cell secretions, called exosomes, to harness their contents for biomarker discovery.
A global problem
According to the 2015 World Alzheimer’s Report, someone in the world develops dementia every three seconds. Of those, up to 70% will have AD. The disease often begins with memory lapses or problems with language, eventually leading to short and long term memory loss. Behavioural and cognitive abilities are also affected, culminating in complete dependence and, ultimately, death.
AD is often recognisable by its symptoms, but a definitive diagnosis can only be obtained post-mortem or through neuroimaging: a procedure that involves the injection of compounds into the patient that are then tracked, via scanning, to identify changes to the brain. “We want to develop a diagnostic test that is less invasive for the patient, more cost-effective and amenable to routine testing,” said Dr Cheng.
Professor Hill and Dr Cheng are three years into game-changing research that may lead to an AD diagnosis via a simple blood test. Exosomes, they believe, contain the material that may provide the genetic answers needed to achieve this.
“Exosomes are particles that are secreted by cells and end up in the bloodstream where they can be collected and isolated,” explained Dr Cheng. “They are packed with protein and genetic cargo, including microRNA (miRNA), which contain genetic signatures that can indicate particular disease states.”
Using next generation deep sequencing, Professor Hill and Dr Cheng screened the exosomal miRNA in an initial trial study and identified 16 abnormal miRNA species (out of 2,500 known miRNAs) in the blood of AD patients when compared to healthy participants.
The next stage of the project, supported by a Dementia Collaborative Research Centres grant, will determine whether the 16 abnormal miRNA are also found in exosomes isolated from post-mortem tissue in the brain.
Professor Hill and Dr Cheng hope their findings will result in a blood test that is able to detect AD in its earliest stages. “A cost effective, early diagnostic test will allow us to administer therapeutic treatments aimed at limiting neurodegeneration before the appearance of symptoms,” said Professor Hill.