This ‘Poo Zoo’ is harvesting living cells from animal dung

By Rebecca Cairns, CNN

(CNN) — Professor Suzannah Williams wishes she didn’t have to spend her days analyzing poop samples. It’s a dirty job; but someone’s got to do it.

Biodiversity is rapidly dwindling, with wildlife populations declining by an average of 73% between 1970 and 2020. For Williams, and her small team at Oxford University in the UK, animal feces contain answers that could help conservationists better monitor wildlife, and perhaps even restore dwindling populations.

When animals defecate, they shed living cells from their intestines, and these can be found on the outside of the dung, says Williams, a professor of fertility and reproductive health.

Living cells contain DNA and genetic information, which can help researchers understand species diversity and could inform breeding programs or conservation efforts.

Typically, wild animals would need to be caught and anesthetized to take a tissue sample, such as a small skin biopsy, which is time-consuming, as well as stressful for the animal, says Williams. Additionally, many laws prevent taking samples for research purposes: in the UK and Europe, taking tissue samples is heavily regulated, unless it directly benefits the health of the individual animal, which makes gathering large amounts of data on genetic diversity tricky, says Williams.

That’s why she started the so-called “Poo Zoo,” established in October 2024 with funding from conservation non-profit Revive and Restore. The project builds on previous research conducted by scientists in Japan, which isolated living cells in mouse stools, although the cells were low quality and contaminated with fecal bacteria, says Williams.

By refining and optimizing methods for cell isolation, Williams hopes to improve the cell quality and offer conservationists a non-invasive way to gather living cell samples — which in the long term could contribute to biobanking, repositories of genetic material, which can be used for IVF efforts for elusive and endangered species

“It’s not that it will make a better sample (than from tissue), that’s definitely not the case. But I can’t walk up to a snow leopard in the wild,” says Williams. “If you did find out where they were pooping, you could put a camera trap and go collect samples, whereas there’s no way you’d be able to collect a sample from those animals otherwise.”

‘An ocean of poo’

Starting with mouse poop, which was easily accessible at the university lab, the team experimented with different methods of diluting and straining the scat to get the cells “as clean as possible” as quickly as possible, to preserve the freshness.

After refining a technique for mice, the Poo Zoo set its sights on a bigger goal: elephant dung. While Williams was eager to work on a species that is often central to conservation efforts, its size presented some big problems.

“With mouse poo, you’ve got little dry pellets. With an elephant, you’ve got an enormous bolus that you’re basically holding with two hands. They’re huge. How do you work with that, and turn it into some cells in a tube without it becoming an ocean of poo and liquid?” Williams explains.

Biobanking researcher Dr. Rhiannon Bolton took on the challenge, in partnership with Chester Zoo, which provided access to fresh elephant feces.

“At the zoo, they do quite a lot of work on fecal analysis, be that looking at the microbiome (micororganisms) or hormones within the poo,” says Bolton, which can help zookeepers monitor animal pregnancies or fertility.

Refining the technique — details of which are being kept tightly under wraps until it’s published in a peer-reviewed paper — was “very much trial and error,” says Bolton, ranging from washing the entire bolus to taking tiny external scrapes.

“At the beginning, there was still quite a lot of debris, and now we’re getting far less in our samples,” she adds.

There are other non-invasive ways of collecting samples, such as hair traps, which use pheromones to attract wild animals and glue to collect hair samples. Researchers have previously used this method to study mammal populations, although Bolton says hair samples may provide fewer cells that are more vulnerable to environmental conditions, while feces offers a reliable and plentiful source of cells.

“The unique protocols we have developed are straightforward and cost-effective, and therefore can easily be rolled out en masse,” she adds.

The team has now successfully isolated living elephant cells multiple times, demonstrating the reliability of their technique, says Williams — and she hopes that once the research is published, the technique can be rolled out in the field. Conservationists often track animals via footprints, fur, and feces, which could provide an opportunity for collection in the wild.

“The only limitation, I think, would be the freshness of the sample,” says Williams. As all of the dung they’ve worked with comes from the controlled environment of the zoo, she speculates that weather conditions might impact the dryness of the dung, and, therefore, the sample. “If it’s in the sun, it might not be the best one, so you might want to make sure it’s one that’s in the shade,” she adds.

Excrement into offspring?

Genetic analysis is just one of the possible uses for the Poo Zoo’s research: there’s also potential to extract cells from stool that can be used to create embryos for artificial insemination.

In 2006, Japanese scientist Shinya Yamanaka discovered that some cells can be “reprogrammed” into other cell types, such as sperm and egg cells, for which he won the 2012 Nobel Prize in Physiology or Medicine. Scientists have used these reprogrammed cells, known as induced pluripotent stem cells or iPSCs, to successfully create healthy mice pups, and are now exploring other species.

However, there are several obstacles to overcome before cells isolated from poop can be useful in bio-banking, says Williams: “The biggest challenge has been, which always was and always will be, is to make sure the samples are clean. Collecting cells from such an environment is incredibly dirty and bacteria-ridden.”

Decontaminating specimens like this is “very, very challenging” and resource-intensive says Dr. Thomas Hildebrandt, a professor of reproduction management at Leibniz Institute for Zoo and Wildlife Research in Germany, one of the largest biobanking facilities in Europe. Hildebrandt is not connected with the poo zoo, but has worked with Williams on previous projects, including one on rhino fertility.

“I think this kind of technology will provide you with important information regarding the genetic pattern of this animal, and maybe even the health status,” says Hildebrandt. However, he’s skeptical that the cell quality will ever be sufficiently clean for iPSC and worries that the fecal contamination might change the “epigenetic profile” — when environmental factors alter how genes work. When creating embryos, he adds, “we should start with the best cells.”

Currently, most biobanking deposits are collected from captive animals, says Hildebrandt. Veterinarians regularly take blood samples when animals are unwell, which can be used in biobanking. Although blood is “much more challenging” to extract cells from than a skin biopsy, it’s simple compared to feces, he says, adding that the legal paperwork to use these samples is often more of a barrier than the extraction process itself.

While collecting from wild animals could add to the diversity of the biobanking collection, Hildebrandt says there are a lot of unknowns, including diseases, that could make the samples unsuitable.

Despite his skepticism, Hildebrandt hopes the project will yield results. “I think science can provide new solutions, and sometimes the solution is not so obvious,” he says.

Dung diversity

While the use of these cells in biobanking is still a long way off, Bolton and Williams believe the Poo Zoo could provide a low-cost solution to gather genetic data in both zoos and the wild, and are now exploring more species to refine their methodology.

“We are losing biodiversity at an absolutely alarming and terrifying rate, and species will not survive unless they are genetically diverse,” says Bolton. “Having a non-invasive option can widen that scope. It can ensure more cells are collected, and more diversity is saved.”

The current rapid loss of wildlife and ecosystems is sometimes referred to as the “sixth mass extinction.” As animal populations become smaller and isolated from other groups, inbreeding is more likely to occur. This reduces genetic diversity, making animals less resilient to threats like disease and climate change, and increases the likelihood of negative traits appearing.

A recent meta-analysis showed that genetic diversity is in decline across hundreds of species, affecting two-thirds of the wildlife analyzed. Another study, which used statistical analysis rather than DNA samples, found that 58% of species in its research pool did not have large enough populations to maintain genetic diversity.

“More genetic diversity makes the population of animals more robust, they’re able to resist diseases better,” says Williams.

Williams sees applications for the technology across all species, as extinctions occur more frequently.

“I would love to never have to do any of this work, and for the world to be a beautiful place, where animals are not endangered and people are not hunting them,” says Williams. “If that was an option versus doing this, I’d stop there. But it’s not; therefore we do this kind of work that I think is very, very important.”

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