The use of patient stem cell-derived mini-brains to study A-T

Research Project information

Principal researcher: Dr Samuel Nayler
Institute: University of Oxford
Cost: £98,200 over 12 months in partnership BrAshA-T
Start Date: 1st of September 2019

What are the researchers proposing to do?
Dr Nayler and team are proposing to make cerebellar organoids or ‘mini-brains’ from induced pluripotent stem cells (iPSCs). iPSCs have been made from the skin of patients with A-T, some of which have had ‘genetic correction’, meaning the faulty ATM gene has been restored to normal. They will make mini brains using established protocols in the Becker lab at the University of Oxford using iPSCs supplied by Malcolm Taylor and Steve Jackson in the UK, and Ernst Wolvetang in Australia. Cells from cerebellar organoids will be sequenced at the Wellcome Trust Centre for Human Genetics. Data will be analysed in a collaborative initiative to provide insight into the dysfunction of Purkinje cells in the cerebellum. This will enable the team to pinpoint the dysfunctional cellular machinery in Purkinje cells allowing them to identify compounds which may be therapeutically viable in A-T.

Animal models of the ‘cerebellum’ (a part of the brain that coordinates and regulate muscular activity) do not accurately demonstrate the neurological aspect seen in human A-T.  Therefore, they cannot be used to further understand A-T and offer limited use in testing drugs that may be effective in human A-T patients. Organoids provide the most relevant model of the human brain which can currently be created. The team have demonstrated that they can derive cell types among those affected in the disease of A-T, including Purkinje neurons (cells that are affected in the cerebellum of A-T patients). They will use cutting edge sequencing technologies to isolate thousands of cells, individually from multiple organoids, to gain the clearest picture yet of the functional consequence of ATM deficiency (the gene affected in A-T). This will allow them to pinpoint defective cellular machinery that could be targeted with drugs to treat the neurological dysfunction in A-T.

How will the research be done?
iPSCs will be grown and differentiated into cerebellar organoids using a defined protocol which makes use of molecules that reproduce development of the cerebellum in vitro (in a dish). Organoids will be validated using a variety of biochemical and immunohistochemical techniques. This involves testing of genetic material and cutting/staining sections of the mini brains to assess they have made the right cell types to learn about the cerebellum. Organoids will be prepared for single-cell sequencing, in collaboration with the core facility at the Wellcome Trust Centre for Human Genetics. This means the team can examine one cell at a time, from thousands of replicates, from large numbers of organoids, giving them the best resolution to dissect out the genetic basis of dysfunctional ATM in Purkinje neurons. Data will be analysed both in-house and with collaborators.

How could it make a difference to the lives of those affected by A-T?
The lab in Oxford are developing a new tool to be used in the fight against A-T. This is a tool that they want other researchers globally to use and to drive their own specific A-T research. They hope that this tool will tell us about how and why the Purkinje neurons suffer in A-T patients and this is the first step to being able to fix them. These tools, once made and validated would offer the ability for ‘avatars’ of A-T patients to be screened with thousands of drugs/compounds from which potential candidates could be selected for future therapeutic testing/use in A-T patients.