Science in Mind

Cambridge stool bank helps meet growing need for fecal transplants

A nose-wrinkling procedure to use human feces to treat a serious gut infection gained worldwide attention a year ago, when a top medical journal published a study showing just how effective it was when compared to routine antibiotic treatment. In the meantime, regulators have been wrestling with what sort of oversight should be used on this scatological treatment.

A group of researchers from the Massachusetts Institute of Technology and the Alpert Medical School of Brown University proposed Wednesday that fecal transplants be regulated similarly to tissue or blood.

In fecal transplants, a slurry of feces containing the gut bacteria from a healthy donor are implanted into the intestine, either through a nasal tube or a procedure similar to a colonoscopy. Official guidelines about how to screen donors and ensure samples are safe will help bring clarity and uniformity to a field that has become something of a Wild West. Researchers are concerned because YouTube videos now offer guidance on DIY fecal transplants for at-home use, and misinformation is abundant. The team that wrote the study has received questions from people suffering from gastrointestinal infections who wonder whether their pets could be used as donors. (They cannot.)

Continue Reading Below

The excitement about the successful use of fecal transplants to treat the gastrointestinal infection C. difficile has also led to a premature interest among the general public suffering from ailments for which it is completely unproven and untested.

“I have pretty serious concerns about this,” said Mark Smith, a graduate student in microbiology at the Massachusetts Institute of Technology who co-wrote the paper published in Nature. “It’s an exciting area of research, but it’s not ready for every patient to get their hands on.”

In Cambridge, Smith has cofounded a nonprofit stool bank called OpenBiome that carefully prepares feces samples for doctors to use in treating C. difficile. The stool bank has already sent out more than 130 samples for transplant into patients, for $250 per treatment. Some hospitals are already running their own stool banks, such as Massachusetts General Hospital, according to the article.

Ultimately, researchers hope that a greater understanding of the key bacteria present in healthy stool, which help reestablish a normal community of microbes in the gut, will guide the development of synthetic treatments. But they worry that if fecal transplants are regulated like a drug now, it will seriously hinder doctors’ abilities to administer the treatment because of how difficult and time-consuming it is to submit an investigational new drug application.

The Food and Drug Administration actually announced last May that it was regulating fecal transplants as drugs, a position that it quickly reversed. The FDA said it would not enforce drug requirements when transplants were used to treat C. difficile infections, for the time being. But larger questions still remain about how the material should be classified.

In the meantime, OpenBiome is pioneering a model that may be able to create a steady supply, by taking a page from nonprofit blood banks. So far, there are three active donors providing samples to OpenBiome, with more awaiting clearance of screening tests. The donors are rigorously tested both before and after a 60-day collection period, and the samples are quarantined until those tests come back clean, in order to ensure that they could not transmit diseases to recipients.

On average, donors drop by the laboratory to make two to three deposits a week into the stool bank, Smith said. They are researchers from the broader Harvard and MIT community, and are paid $40 per donation. Smith has even created a kind of informal competition among the donors to see who can make the most generous contributions. So far, the researchers have learned that people with large body mass have something of an advantage, and the trophy so far for largest single deposit—a squatting wrestler—has gone to a person who provided a sample that could be used to treat 10 people.

Smith said that developing the stool bank is far from what he imagined he’d be doing when he started graduate school, but that his main motivation is understanding the science behind the remarkable treatment. He is working to enroll some of the patients that receive the samples in a research study so that scientists can begin to discern which bacterial strains are the key ones that are repopulating their guts. That information could help guide the development of a synthetic treatment—one that could easily be regulated as a drug. Some local companies, including Seres Health in Cambridge and Vedanta Biosciences in Boston, are working on developing this idea.

Until then, Smith thinks that the stool bank model may be the best one—more cost-efficient than individual hospitals setting up their own facilities, protocols for donors, and safety testing.

“My personal interest is in part because it’s a cool thing to do, and I had a family friend that needed treatment and couldn’t get it,” Smith said. But it is also a solution to a research problem that he ran into two years ago when he tried to begin understanding at a detailed biological level how fecal transplants had their beneficial effects. It was very difficult then to recruit patients to study because so few doctors were doing the procedure. The stool bank provides a medical resource and a powerful potential research platform.

As clinical trials of fecal transplants for an array of other problems continue, there should also be greater clarity on the true potential of the technique to treat conditions like inflammatory bowel disease or type 2 diabetes—and the scope of the need for a nationwide network of stool banks.