Faculty takes on Alzheimer’s
Biomedical engineers use new imaging technology to better understand disease
By Meghan King
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Alzheimer’s disease is a big health burden … It not only changes the life of the patient, but it changes the life of the whole family.Professor of biomedical engineering|
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A new view
Richard & Loan Hill Professor Xincheng Yao is supported by multiple NIH National Eye Institute grants for functional imaging of the retina. As one part of the central nerve system, the retina offers a unique window to enable noninvasive assessment of neurodegeneration due to AD.
Yao is collaborating with Professor James Lee on a grant proposal to combine the imaging assessment of AD using optical coherence tomography angiography (OCTA). They are also attempting to identify if photo-biomodulation can be used to prevent or delay the neurodegeneration in the retina correlated with the disease.
Yao works with optical coherence topography (OCT) and OCTA, which image the microvasculature of the retina and the choroid. OCTA images show the difference in functional blood flow over time, and they can enhance the visibility of blood vessels.
“We use the blood flow information to enhance the visibility of individual blood vessels so you can compare OCTA to OCT,” Yao said.
Lee and Yao are using functional OCTA to check the retinal degenerations in an AD mouse model. They can use optical imaging technology to access the eye without damaging it or the brain. Using the quantitative analysis of the blood vessels, like density or diameter, will show that some optical features may reflect the retinal defects or are correlated with that function in the future.
Yao said that he and Lee are hoping for earlier detection of Alzheimer’s Disease and examine the progression of the disease or the treatment outcome over time without damage to the animal or human body.
Examining the brain’s defenses
Over the past 15 years, Lee has received NIH grants to support his Alzheimer’s research. As a traditionally trained engineer, Lee applies engineering techniques and principles to investigate the roles of membrane biophysics and mechanics in the pathology of AD.
Through the support of his current NIH grant, Lee is looking into the blood-brain barrier, a controlled border made of endothelial cells that allow transports of biological materials selectively going in and out of the brain, which are essential for the brain’s metabolic activity and neuronal function.
He is using cell models to see what happens if we allow endothelial cells that have direct interactions with toxic proteins found in Alzheimer’s brains—amyloid beta peptide and tau.
When using endothelial cells to make a blood-brain barrier model, these toxic proteins make the model become leaky and stickier to white cells. This model helps explain why increased white blood cells from peripheral blood to get to the brain tissue of AD patients, which may further exacerbate the disease.
“When too many white blood cells exist in the brain, they might cause high levels of neuroinflammatory and oxidative stress,” Lee said.
The blood-brain barrier plays a key role in the generation and maintenance of chronic inflammation during AD.
Inflammation, Lee said, plays a key role in many neurodegenerative diseases, such as Alzheimer’s. It is a double-edged sword as too much inflammation is not good and will exacerbate the disease, however, too low inflammation might prevent healing.
Throughout all his research, Lee is looking to slow down the progression of Alzheimer’s Disease in patients.