A team of researchers from Harvard University has claimed that like stem cells, samples of gut microbiota preserved at an early age when a person is healthy, could be used later in life to treat diseases.

Gut microbiota refers to the collection of microorganisms (e.g., bacteria, fungi, viruses, and archaea) that live in the gastrointestinal tracts of vertebrates — including humans. This biota changes through life, but it can be preserved in the form of stool samples. The transfer of preserved fecal material from a healthy donor into a patient’s gastrointestinal tract for treating diseases is called fecal microbiota transfer (FMT). 

Increasingly, research has found that FMT can help in a number of different conditions. But could your own poop also be used for the same purpose?

In their study, the researchers have proposed autologous FMT, a treatment method in which the donor and recipient of the stool samples are the same person. The treatment procedure using stool samples is similar to stem cell therapy but the targeted diseases are different. Explaining the difference between the two, Associate Professor at Harvard Medical School Yang-Yu Liu told ZME Science:

“The idea is quite similar. But their treatments aim for different diseases. The stem cells in cord blood can be used to treat cancers, blood disorders, bone marrow failure syndromes, metabolic disorders, and immune disorders. The fecal microbiota can be used to treat diseases associated with disrupted microbiota, e.g., rCDI, Irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), obesity, aging, etc.”

This isn’t something for the distant future — it’s happening now. The first stool bank has already been opened in Somerville, Massachusetts. It is run by OpenBiome, a nonprofit focusing on human biome research. Here is how stool banking could work.

The need and significance of stool banking

The researchers highlight that in the last few decades, the gut microbiome in humans has undergone drastic changes due to alterations in our eating behavior. Many people are eating less healthily, and more — according to a  2016 study, as compared to the 1970s, the calorie intake of an average American in 2010 was 23% higher. Moreover, the calorie intake was found to be much more than what an adult requires to maintain his or her normal weight. Another surprising report from the Centers for Disease Control and Prevention (CDC) reveals that about 14% of the calories consumed by children and adolescents in the US on a daily basis come from fast food. Living on an unhealthy diet (alcohol, sugar-based cold drinks, junk food, preserved and processed edibles) from a young age can lead to the occurrence of various body ailments such as diabetes, asthma, allergies, etc, at later stages of life. The researchers believe that autologous FMT could be used to treat the consequences arising from unhealthy eating trends.    

Previously, FMT (not autologous) has been employed to treat Clostridioides difficile infection, a disease that affects the human colon and can cause diarrhea, fever, and even death. Every year, about 29,000 people lose their lives due to this contagious infection. However, there is a catch with the FMT treatment – it is beneficial for the patient only when the gut microbiome from the donor is well-accepted by the host’s body, which is not always the case.    

This is why FMT can not prove to be effective for every patient. So to overcome this challenge the researchers at Harvard proposed stool banking for the purpose of autologous FMT. Since the donor and recipient are the same in the autologous treatment, there is no chance of treatment failure due to a mismatched stool sample.

“Autologous FMTs have the potential to treat autoimmune diseases like asthma, multiple sclerosis, inflammatory bowel disease, diabetes, obesity, and even heart disease and aging,” said Scott T. Weiss, co-author, and professor of Medicine at Harvard. 

Challenges with banking of stool samples

Although autologous FMT is a great method to treat diseases, stool banking is a challenging and expensive process. Researchers are still unsure if cryo-preservation of stool samples for years could have any effect on their usability. While discussing the challenges associated with the storage of fecal matter, co-author of the study Shanlin Ke wrote:

“Autologous transplants would naturally avoid or at least mitigate donor-recipient compatibility issues, but a major disadvantage of autologous transplants is the need for long-term cryopreservation of stool samples, typically requiring liquid nitrogen storage. He further added, “The long-term safe storage and subsequent resuscitation and cultivation of stool samples is a fundamental research question by itself. 

More research is required to discover the best stool banking, preservation, and cultivation methods. The authors of the study are currently working with microbiologists to perform preclinical experiments to test this idea of rejuvenating the gut microbiome. The study (opinion article) is published in the journal Trends in Molecular Medicine.