Pilot Study Success Story
Published on June 29, 2021
Animal Free Research UK funding has enabled Dr Paul Holloway at Oxford University to secure a £150,000 grant with Cambridge University and an Oxford-based biotech company to use their organ-on-a-chip system to test a novel therapeutic approach to treat genetic stroke disorders.
Here is an overview of Paul’s project:
“Stroke is the largest cause of adult disability and a leading cause of death worldwide. Despite significant research efforts, over 1000 prospective drugs tested in animals have failed to deliver an effective treatment in humans. However, methods for testing stroke drugs in human cells in a dish (in vitro) do not replicate the complex 3D interactions between different brain cell types that underlies brain function.
Animals are often used to study events that occur during stroke, such as disruption of the specialist barrier formed by brain blood vessels that protect the brain (the blood brain barrier). This work has helped develop an in vitro stroke model that uses organ-on-a-chip technologies to create 3D brain blood vessels which interact and communicate with brain cells providing a system that much better reflects the structure of the blood brain barrier (image 1).
These vessels can be blocked with miniature clots to mimic stroke enabling new possibilities to test stroke drugs in human cells to improve prediction of drug efficacy whist also removing the need for animals in research.
Image 1. Organ-on-chip techniques allow for models that better reflect the blood vessels of the brain. A). Brain blood vessels in animal testing. B) traditional cell culture of brain blood vessel cells just form a flat layer. C. Organ on chip systems can create brain blood vessels that are much closer to those in the brain.
Human brain cells however are difficult to obtain and researchers often use either cancerous cells or cells left over from neurosurgery, which may not reflect the normal functioning of these cells. To overcome this limitation we have used induced pluripotent stem cell (iPSC) technologies. iPSCs are adult cells which have been reprogrammed to become like stem cells. Then, like stem cells, they can then be further developed to become any type of cell in the body (in this case, brain cells).
From a single adult donor we can turn these cells into stem cells and then direct their growth specifically into cells of the brain (image 2). In our organ-on-a-chip system we are able to create a model that represents a specific patient.
In fact, funding from Animal Free Research UK for this pilot study has enabled a new collaboration with laboratories in Cambridge to create specific brain blood vessel models of patients that have genetic mutations that cause stroke. Their funding has also lead to us securing a £150,000 grant with Cambridge University and an Oxford based biotech company to use this system to replace the use of animals needed in testing a novel therapeutic approach to treat stroke disorders.
Image 2. iPSC technologies were used in this project to create the different brain cells that make up the blood brain barrier: blood vessel cells (endothelial cells), Vessel support cells (Pericytes), Brain support cells (Astrocytes) and neurons.
Funding from Animal Free Research UK has also enabled us to further develop our organ-on-a-chip brain blood vessel model (image 3) to study how cell interactions can breakdown following stroke.
We can mimic stroke either by removing glucose and oxygen from the device or by blocking the flow through the vessels (as occurs in stroke) with miniature clots. Both techniques starve the cells of oxygen and glucose and cause cells to die, breakdown of cell-cell communication and disruption of the blood brain barrier. This mimics a number of important disease processes in stroke and allows us to study certain therapeutic approaches in this model which were only previously possible in animals.
We are now using this in our lab to do exactly this. We’re also now collaborating with groups from Imperial College London and Brunel University to use this model to replace the use of animals in testing novel anti-inflammatory drugs for stroke.
Image 3. The Organ on chip device, based on our collaborative work with Abe Lee at the University of California Irvine uses miniature channels in a flexible transparent silicone (A) to position brain cells in a gel (B). Fluid flow over the cells stimulates cellular self-assembly into brain blood vessels (C) which are perfused with dyes (red) to assess the function of the blood brain barrier.
This Animal Free Research UK funded Pilot Study Grant has jump started a number of projects that will ultimately replace the use of animals in stroke research and will allow more human relevant research. We will continue to collaborate with key players in the stroke field to promote and further characterise this model. We also aim to further develop this model to study how white blood cell interact with vessels and post-stroke inflammatory responses to allow wider impact, better pre-clinical predictive power and continue to replace animals used in research.”
Dr Paul Holloway
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