A new study from WashU Medicine identifies a previously unknown way that cells purge waste in a process that helps them revert to a stem cell-like state to promote healing after injury. Here, three mouse stomach cells (numbered) are shown jettisoning cellular debris through cavities (white) that form in their membranes. The researchers dubbed the new purging process “cathartocytosis,” combining Greek root words meaning cellular cleansing. Credit: Jeffrey Brown
Scientists have uncovered a strange and messy new way that injured cells may heal themselves.
In addition to known processes like programmed cell death and controlled recycling, researchers discovered that cells can suddenly “vomit” their internal machinery, purging themselves to reset into a stem cell-like state. This shortcut, called cathartocytosis, speeds up regeneration but leaves behind waste that may fuel chronic inflammation and cancer.
A Hidden Cellular Purge
When cells are injured, they activate a series of carefully controlled responses to repair the damage. These include a well-known self-destruct routine that removes dead or defective cells, along with a more recently recognized ability for aging cells to revert to a younger state so they can rebuild healthy tissue.
In a new study using mice, researchers from Washington University School of Medicine in St. Louis and Baylor College of Medicine uncovered another healing strategy that had not been seen before. The team identified a cellular purge that helps damaged cells quickly reset into a stem cell-like form. They named this newly described process cathartocytosis, drawing from Greek words meaning cellular cleansing.
The findings, published in Cell Reports, came from experiments on stomach injury. By using this model, scientists were able to examine how cells succeed or fail at repairing themselves after being harmed by infection or inflammatory disease.
A Cellular Cleanse With a Twist
“After an injury, the cell’s job is to repair that injury. But the cell’s mature cellular machinery for doing its normal job gets in the way,” said first author Jeffrey W. Brown, MD, PhD, an assistant professor of medicine in the Division of Gastroenterology at WashU Medicine. “So, this cellular cleanse is a quick way of getting rid of that machinery so it can rapidly become a small, primitive cell capable of proliferating and repairing the injury. We identified this process in the GI tract, but we suspect it is relevant in other tissues as well.”
Brown compared cathartocytosis to “vomiting” out cellular waste, a shortcut that allows the cell to clear clutter and concentrate on rebuilding tissue faster than it could through the slower, step-by-step breakdown of waste.
But shortcuts often come with drawbacks. The researchers note that cathartocytosis is rapid but disorderly, which could explain why some healing processes fail, particularly during long-term injury. If the process continues unchecked, as during infection, it may lead to chronic inflammation and ongoing cellular damage, conditions that create fertile ground for cancer. The buildup of expelled waste itself may also serve as a marker for tracking or detecting cancer, the investigators said.
A Novel Cellular Process
The researchers identified cathartocytosis within an important regenerative injury response called paligenosis, which was first described in 2018 by the current study’s senior author, Jason C. Mills, MD, PhD. Now at the Baylor College of Medicine, Mills began this work while he was a faculty member in the Division of Gastroenterology at WashU Medicine and Brown was a postdoctoral researcher in his lab.
In paligenosis, injured cells shift away from their normal roles and undergo a reprogramming process to an immature state, behaving like rapidly dividing stem cells, as happens during development. Originally, the researchers assumed the decluttering of cellular machinery in preparation for this reprogramming happens entirely inside cellular compartments called lysosomes, where waste is digested in a slow and contained process.
From the start, though, the researchers noticed debris outside the cells. They initially dismissed this as unimportant, but the more external waste they saw in their early studies, the more Brown began to suspect that something deliberate was going on. He utilized a model of mouse stomach injury that triggered the reprogramming of mature cells to a stem cell state all at once, making it obvious that the “vomiting” response — now happening in all the stomach cells simultaneously — was a feature of paligenosis, not a bug. In other words, the vomiting process was not just an accidental spill here and there but a newly identified, standard way cells behaved in response to injury.
Although they discovered cathartocytosis happening during paligenosis, the researchers said cells could potentially use cathartocytosis to jettison waste in other, more worrisome situations, like giving mature cells that ability to start to act like cancer cells.
The Downside to Downsizing
While the newly discovered cathartocytosis process may help injured cells proceed through paligenosis and regenerate healthy tissue more rapidly, the tradeoff comes in the form of additional waste products that could fuel inflammatory states, making chronic injuries harder to resolve and correlating with increased risk of cancer development.
“In these gastric cells, paligenosis — reversion to a stem cell state for healing — is a risky process, especially now that we’ve identified the potentially inflammatory downsizing of cathartocytosis within it,” Mills said. “These cells in the stomach are long-lived, and aging cells acquire mutations. If many older mutated cells revert to stem cell states in an effort to repair an injury — and injuries also often fuel inflammation, such as during an infection — there’s an increased risk of acquiring, perpetuating, and expanding harmful mutations that lead to cancer as those stem cells multiply.”
Infection, Inflammation, and Cancer
More research is needed, but the authors suspect that cathartocytosis could play a role in perpetuating injury and inflammation in Helicobacter pylori infections in the gut. H. pylori is a type of bacteria known to infect and damage the stomach, causing ulcers and increasing the risk of stomach cancer.
The findings also could point to new treatment strategies for stomach cancer and perhaps other GI cancers. Brown and WashU Medicine collaborator Koushik K. Das, MD, an associate professor of medicine, have developed an antibody that binds to parts of the cellular waste ejected during cathartocytosis, providing a way to detect when this process may be happening, especially in large quantities. In this way, cathartocytosis might be used as a marker of precancerous states that could allow for early detection and treatment.
Guiding Healing Without Harm
“If we have a better understanding of this process, we could develop ways to help encourage the healing response and perhaps, in the context of chronic injury, block the damaged cells undergoing chronic cathartocytosis from contributing to cancer formation,” Brown said.
Reference: “Cathartocytosis: Jettisoning of cellular material during reprogramming of differentiated cells” by Jeffrey W. Brown, Xiaobo Lin, Gabriel Anthony Nicolazzi, Xuemei Liu, Thanh Nguyen, Megan D. Radyk, Joseph Burclaff and Jason C. Mills, 30 July 2025, Cell Reports.
DOI: 10.1016/j.celrep.2025.116070
This work was supported by the National Institutes of Health (NIH), grant numbers K08DK132496, R21AI156236, P30DK052574, P30DK056338, R01DK105129, R01CA239645, F31DK136205, K99GM159354 and F31CA236506; the Department of Defense, grant number W81XWH-20-1-0630; the American Gastroenterological Association, grant numbers AGA2021-5101 and AGA2024-13-01; and a Philip and Sima Needleman Student Fellowship in Regenerative Medicine. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
