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EARA Newsletter

October 6th 2025

 
 

EARA News Digest 2025 - Week 41


Welcome to your Monday morning update, from EARA, on the latest news in biomedical science, policy and openness on animal research. 

This week: Zebrafish larvae could guide cancer therapies; Gerbils reveal how hearing works; Tracking Alzheimer's brain alterations in living mice.

Zebrafish larvae could guide cancer therapies 

Researchers in Canada were able to mimic children’s response to cancer therapies in zebrafish larvae, which could provide a platform to inform clinical decisions in real-time. 

The ability to identify specific genes contributing to a patient’s cancer has revolutionised cancer treatment, but 30% of aggressive cancers in children do not have specific genetic alterations, making it difficult to select an appropriate therapy. In these cases, an alternative is to transfer cells from the tumour of each patient into a mouse to study how the tumour would respond to different therapies. However, this process is long and in certain cases the tissue does not form tumours in mice. 

Researchers at the CHEO Research Institute have tested a similar approach using zebrafish. The team injected tumour cells from ten patients being treated for different cancers into fish larvae and treated the water with different therapies to analyse how the tumours responded to therapies. Then, the researchers compared the effect of the drugs on the size of the tumours both with the clinical outcomes and the effects of the drugs in mice with tumours from the same patients. The zebrafish platform accurately predicted the responses to 11 of 12 treatments and the researchers could grow tumours from all patients, whereas in mice the process failed in three cases. 

Jason Berman, leader of the study published in Cancer Research Communications, said: "Our research shows that these small tropical fish provide fast, accurate information about how a child may respond to different therapies, saving time and guiding personalized treatment decisions that have a higher likelihood of working for each child." 

 

 

Gerbils reveal how hearing works

Scientists in the US, in a study using gerbils, have kept tissue from a crucial inner ear organ alive outside the body, creating an unprecedented system that could allow researchers to understand how hearing works and test potential treatments for hearing loss. 

The cochlea is a spiral-shaped organ in the inner ear that has a crucial role in hearing. This organ contains approximately 16,000 sensory cells, called cochlear hair cells, which amplify and transform sound into electrical signals that can be interpreted by the brain. Damage in these cells is responsible for most hearing loss. Researchers at Rockefeller University removed tiny pieces of tissue from gerbils’ cochlea, whose hearing range is similar to humans, and placed them in a chamber that kept the tissue warm and bathed in nutrient-rich fluids, imitating the environment inside the body. The team then played sounds on a tiny speaker and observed how the cochlea responded. 

With this system, the researchers observed directly that a process called Hopf bifurcation - which is a tipping point that allows even faint sounds to be amplified - previously seen in other animals such as bullfrogs, was also central to how mammals hear.  

"So far, no drug has been approved to restore hearing in sensorineural loss..." said Francesco Gianoli, co-author of the two studies published in PNAS and Hearing Research. "But now we have a tool that we can use to understand how the system works, and how and when it breaks - and hopefully think of ways to intervene before it's too late." 

 

 

Tracking Alzheimer's brain alterations in living mice     

A team based in the UK and Italy has developed a method to monitor a key brain alteration found in Alzheimer’s disease in the brain of living, freely moving mice using optic fibres. 

Alzheimer's disease is marked by the buildup of amyloid plaques in the brain. Until now, most ways of studying these deposits required directly observing the brain tissue. Researchers at the University of Strathclyde, UK, and the Italian Institute of Technology implanted a device with tapered optical fibres into living mice to capture light from the brain. By injecting mice with a dye that goes into the brain and turns amyloid plaques fluorescent, the researchers observed fluorescence only in mice genetically altered to show Alzheimer’s symptoms and not in healthy animals. The intensity of the fluorescent light increased with age, which is consistent with disease progression.  

While this approach, published in Neurophotonics, cannot distinguish individual plaques, it reveals fluorescent levels in different depths of the brain, allowing scientists to track changes long-term in deep brain regions and opening the door to study how treatments affect disease progression. 

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