A team of scientists in the US, including one from Ireland, have built a chip based replica of the network of blood vessels that supply but also protect the brain, the so-called blood-brain barrier (BBB).

The development is important because it is the first time such chips have been produced, offering a new method for studying the effects of drugs and disease on the brain and its blood vessels.

The BBB is a unique structure of vessels that enables oxygen and nutrients to cross from the blood into the brain and waste molecules from the brain into the blood.

But the BBB is also capable of preventing toxins and other damaging substances from crossing into our grey matter.

Certain drugs, such as methamphetamine, can disrupt this mechanism, exposing neurons to possible damage.

Trying to establish how the BBB actually works, and the influence it has on the regulation of the brain, has been a challenge for scientists for some time.

Attempts have been made to study this by manipulating cells in a dish and natural human brain tissue, but the former has proven too simple and the latter too complex.

But scientists at the Wyss Institute for Biologically Inspired Engineering in the US, including Irish researcher Edward FitzGerald who is now studying for a PhD at Uppsala University, say they have developed a chip-based system to overcome these challenges.

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The invention mimics the BBB, linking the flow of microfluids across three polymer chips that have channels lined with human cells.

"The beauty of this work is that it opens up another dimension for neurological research that no other method could by decoupling a very dense organ to unveil new interactions between the different structures within the brain," said first author Ben Maoz, Ph.D., a former Technology Development Fellow at the Wyss Institute and current Assistant Professor at Tel Aviv University, Israel.

The first chip supplies the second with an artificial cerebrospinal fluid that contains the cells that support the BBB.

The third chip gathers the fluid as it flows out of the second one.

The second chip's flow channel is separated by a semipermeable membrane from a compartment that has human brain neurons and other cells in it.

Fluid can then flow from each chip to the next, allowing scientists an unprecedented opportunity to study what happens at each stage.

Evidence of this was apparent when the researchers tested what happens when methamphetamine is added to the model, to see whether it disrupts the junctions of the cells of the BBB as it does in human tissue.

They found the model does respond to meth, just as the human brain does, and as a result it could become an important tool for understanding how drugs and other substances work and for developing new treatments.

The research team also discovered that the cells in the chips were somehow influencing each other to maintain proper cell function and established that the health of our blood vessels could have a direct impact on how our minds function.

"Blood vessels are frequently thought to just be a barrier or a transporter of chemicals. But when we looked at the linked BBB-Brain Chips, we noticed that there seemed to be some crosstalk between the endothelial cells and the neurons," explained co-author Anna Herland, Ph.D., a former Postdoctoral Fellow at the Wyss Institute who is now an Associate Professor at the Royal Institute of Technology and the Karolinska Institute in Stockholm, Sweden.

The research is published in the journal Nature Biotechnology.