Researchers in China have successfully frozen and thawed human brain tissue, after which it regained normal function.
They hope the new technique will improve ways of studying neurological conditions.
Usually, brain tissue doesn’t survive freezing and thawing – although that hasn’t stopped people paying to have either just their brains or their entire bodies cryogenically frozen in the hope of being reanimated in the future.
However, Dr Zhicheng Shao and his colleagues at Fudan University in Shanghai, China, have successfully developed a solution which can keep brain tissue alive while frozen.
The team used human embryonic stem cells to grow brain organoids – small clusters of self-organising brain cells – for three weeks, after which they developed into different types of brain cells.
They then placed the organoids in different chemical compounds they hoped may help preserve the tissue while frozen in liquid nitrogen for at least 24 hours – including sugars and antifreeze.
After thawing the samples, the team monitored them for growth and cell death over the next two weeks. Based on the most successful, the researchers then repeated the process using different combinations of the chemical compounds, eventually finding one that led to the least cell death and most growth after thawing.
The winner is called ‘Medy’, short for the four compounds methylcellulose, ethylene glycol, DMSO and Y27632.
Further testing of Medy revealed not only that the brain organoids continued to grow for up to 150 days after thawing, but the compound was also effective for use in freezing and thawing living brain tissue. The team tested 3-millimetre cubes of brain tissue removed from a 9-month-old girl with epilepsy, and found they continued to remain active for at least two weeks after being thawed.
Writing in the journal Cell Reports Methods, the team said: ‘Fresh, viable human brain tissue with natural pathological features is a more reliable model to study neural diseases [than organoids].
‘However, with limited accessibility and manipulability, cryopreservation and reconstruction of living brain tissue with specific pathological features remain hugely challenging, as it is hard to maintain the survival of large amounts of functional neurons.
University of Birmingham professor Dr João Pedro Magalhães said he was impressed with the findings, and the solution’s ability to prevent cell death and preserve function.
‘We know brain cells are very fragile and sensitive to stress,’ he said, adding that one day the work could be ‘one small step’ towards freezing entire brains.
‘Thinking decades or centuries ahead, we can imagine patients being cryopreserved when they have a terminal condition or astronauts being cryopreserved in order to travel to other star systems,’ he said.
