Kidney researcher wins University of Manchester 3Rs prize

A researcher from The University of Manchester has bagged a prize for developing a powerful way to minimize suffering in animals when studying kidney disease. 

The new tool –  now used across the world – was developed by research fellow Dr Richard Naylor who made it possible to use zebrafish larvae to easily and quickly screen new drugs for treating different kidney diseases. 

Replacement, reduction and refinement – known collectively as the 3Rs –  are an increasingly important area of biological research. 

By law scientists must demonstrate they have adhered to the principles of the 3Rs before their project license is granted by the Home Office. 

Dr Naylor will pick up his award today (14 November) at the second ever University of Manchester  3Rs symposium, organised by the University’s animal unit, where  scientists will hear about the latest advances in 3Rs science. 

Using organisms that are not able to feed independently and are therefore considered to be minimally sentient – the judges recognised the tool as a novel alternative to mammals but also for its ability to reduce animal numbers and enhance the care they receive. 

Kidney disease is a major cause of illness and accounts for 10% of all deaths in humans. 

Protein in urine is produced when kidneys do not work properly and is easily tested in humans with a simple dipstick. 

Zebrafish- which have similar genetics to humans and possess 80% of human disease-causing genes – are a popular species used by research scientists because they produce large numbers of eggs (200 to 300 per week per female), which develop externally. 

In the past it was virtually impossible to test for protein in the urine of zebra fish larvae because the tiny amounts of urine produced are immediately diluted in the fish tank. 

However, a new genetically modified zebrafish larvae model, designed and generated by Dr Naylor and his team, contains a luminescent molecule called NL-D3 in its blood. 

When kidneys are damaged, NL-D3 leaks out of the kidneys and into the urine. NL-D3 can easily be detected in embryos using a luminometer which measures the light produced by urine in the water. 

As a result, scientists can now easily test for the level of protein in high numbers of the organisms which – at less than 5 days old – are not considered to be fully sentient under the law. 

The team tested the new tool by generating a zebrafish model of Alport syndrome, a kidney disease characterized by protein in the urine, publishing their results in the prestigious journal Kidney International. 

In Alport zebrafish, levels of NL-D3 increased but could be subsequently reduced using captopril, a drug that lowers blood pressure, demonstrating the efficacy of the tool. 

Dr Naylor said: “Finding 3Rs solutions to animal research is incredibly important because as scientists we care about the welfare of the animals we are privileged to work with. 

“That is why it is so exciting we have demonstrated how is possible to conduct fundamental research on kidney disease without necessarily relying on mammalian models. 

“Testament to this, we have had seven research groups in the US and Europe request embryos be sent to them. 

“And even more excitingly, we are currently collaborating with a large pharmaceutical company to model acute kidney injury and screen drugs to treat it.” 

Dr Maria Kamper, Director of the animal unit at the University of Manchester said: “As Director of the Biological Services Facility, I am delighted to present our inaugural University of Manchester 3Rs prize to Dr Naylor and his team. 

“Their innovative work exemplifies our commitment to advancing scientific discovery while upholding the highest standards of animal welfare. The widespread adoption of this model by kidney disease researchers worldwide proves it is an outstanding achievement in the 3Rs space.” 

Replacing mouse models
Until now, protein in the urine as a marker of kidney dysfunction in disease and in response to drug treatments was mainly used in mouse models or from human patients. But with the new tool, the ability to use zebrafish to accurately monitor kidney dysfunction increases the appeal of pre-independent feeding stage zebrafish to model kidney disease for researchers worldwide. 

Fewer numbers needed
Previously, high numbers of embryos were needed due to high variability in methods used to test kidney dysfunction in zebrafish. The new tool, however, has reduced the number of procedures needed to be performed on zebrafish embryos to zero.  As the scientists now only need to analyse embryo medium, no animals are injected or are required to be anaesthetized. And fewer larvae are needed to achieve statistical significance. 

No need to anaesthetize the embryos
Before the paper was published, the only way to measure kidney dysfunction in zebrafish was to inject fluorescent dextran directly into the animals and observe how quickly the fluorescence was lost from the blood vasculature over the subsequent days. The approach meant having to anaesthetize zebrafish embryos repeatedly, which is now lo longer necessary.

• The paper A novel nanoluciferase transgenic reporter measures proteinuria in zebrafish is published in Kidney International
• Images are of zebrafish larvae