Did you know that nanoparticles (the very tiny particles) in polluted air might enter the
human brain, which could be an environmental factor that contribute to Alzheimer’s disease?
But how nanoparticles enter the brain remains unknown and is a topic on intensive research.
I’m Dr. Zhiling Guo. I am a research fellow at the University of Birmingham. I have worked as a Marie
curie research fellow in the Environmental Nanoscience group over the past two years.
My marie curie project studies the transport of engineered nanomaterials across the
blood-brain-barrier to understand both the benefits for medicine and the potential risks,
with results just published in the journal Proceedings of the National Academy of Sciences.
The blood-brain barrier, known as the BBB, is a physical barrier
composed of a tightly packed single cell layer that lines all blood vessels , and separates the
blood from the brain Thanks to the BBB, the human brain is a well-protected organ.
The BBB keeps potentially dangerous toxins and pathogens outside the brain, while allowing oxygen
and essential nutrients in. The BBB is extremely good at what it does, however, it isn’t perfect.
So here at University of Birmingham we’ve made a recent discovery - we’ve found that
nanoparticles have the potential to pass， from the bloodstream to brain using a cellular model,
and are exploring how the nanoparticles do this. Nanoparticles can be naturally generated
(think volcanos or diesel exhausts from cars) or manufactured for different application purposes.
There are already thousands of different types of engineered nanomaterials on the market, for
example, zinc oxide nanomaterials which have been widely used in sunscreen cream and nappy cream.
And these nanomaterials are made with different characteristics such as different composition,
shape, size, surface charge and coatings. These characteristics can make their biological effects
and behaviour distinct from each other, and these characteristics are the key
to understanding their potential transport across BBB.
We created a library of metallic nanomaterials with different particle compositions, sizes,
and shapes, including ones similar to those widely applied in commercial products such as
silver, iron oxide, zinc oxide and cerium oxide nanoparticles.
To analyse their transport across BBB, we used a well-established in vitro cell-based model
and a set of new analytical techniques. With these We were able to
quantify and image the transport and transformation of the nanoparticles inside the
BBB and determine the small portion that were able to reach the brain side of the cellular barrier.
We found that the physiochemical properties of metallic nanomaterials influences how
effective they are at penetrating the in vitro model of the blood brain barrier and their
potential levels of toxicity in the brain. . Higher concentrations of spherical and
disc-like silver nanomaterials and zinc oxide, which have high dissolution, for example, may
damage cells and cause increased permeability of the BBB, therefore, allowing even more NMs to
cross the BBB by squeezing in between the cells, in a process called paracellular transport.
Also, nanomaterials can transport through well-regulated transport routes used to nourish
the brain, called the transcytosis-mediated routes, although this portion was relatively low.
The data presented in our study not only provide important new insights into nanomaterials
interactions with, and transport through and from the BBB, but also will help to design
safer nanomaterials and could open up new ways of targeting hard-to-reach locations
when treating brain diseases such as Alzheimer’s and brain cancer.
Although you may not know it, nanoparticles are part of our daily lives being present in
cosmetics and health-care products. It is important to understand that our work was
performed in a model system and as such doesn’t yet prove that they can cross the
human BBB – indeed the body has multiple other barriers that particles have to cross in order to
even reach the blood stream (the air-lung barrier for example), but the in vitro model
data do suggest that there is this potential and that to ensure human safety we need to continue
researching these important questions. Thank you for listening and watching.
If you want to know more the paper is available in the link below.