Frozen human brain tissue works perfectly when thawed 18 months later

In good news for future animation figureheads, there might be a new way to revive frozen brains without damaging them. Scientists in China have developed a new chemical concoction that lets brain tissue function again after being frozen.

Freezing is effective at keeping organic material from decomposing, but it still causes damage. As the water inside turns to ice, the crystals tear apart the cells. That’s why frozen meat or fruit goes a bit mushy after it’s defrosted – but a bigger problem is that it also happens with organs or tissues chilled for transplant or research.

For the new study, scientists at Fudan University in China experimented with various chemical compounds to see which ones might work to preserve living brain tissue during freezing. They started by testing out promising chemicals on brain organoids – small, lab-grown lumps of brain tissue that develop into different types of related cells.

The organoids were submerged in the various chemicals, then frozen in liquid nitrogen for 24 hours. Then they were quickly defrosted in warm water, and checked for function, growth and signs of cellular damage over time. The chemicals that protected the mini-brains the best then went through to the next round, which involved trying various combinations in similar freezing and defrosting tests.

Eventually, the researchers arrived at the most promising mixture, which they called MEDY, after the four main ingredients: methylcellulose, ethylene glycol, DMSO and Y27632. The team grew mini-brains to different ages, from four weeks to more than three months, froze them in MEDY, thawed them out, then continued monitoring them for a few weeks after.

Intriguingly, brain organoids preserved in MEDY showed similar growth and function patterns to those that had never been frozen. Incredibly, one batch was frozen in MEDY for as long as 18 months, and still showed similar protections against damage after thawing.

The team also froze samples of living brain tissue taken from a human epilepsy patient, and found that MEDY protected them from damage. The process didn’t disrupt the structure of the brain cells, and even preserved the pathologies of epilepsy – that’s important, because it means samples can be frozen for later study or analysis without damage from the freezing process confusing the results.

The most immediate impacts for the new freezing tech are that it allows brain organoids and samples to be stored longer for biomedical research, but eventually it could be applied to whole brains, and other tissues.

The research was published in the journal Cell Reports Methods.

Source: Fudan University via New Scientist