Cells have a variety of processes and pathways that can repair damage, remove trash and debris, and boost healing. Scientists have now discovered a novel process in which cells eliminate stuff, and could aid in healing by helping cells go back to a state in which they are more like stem cells that can divide quickly and differentiate into many cell types. This newly identified process is called cathartocytosis. The findings, which relied on a mouse model of stomach injury, have been published in Cell Reports.
“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,” explained first author Jeffrey W. Brown, MD, PhD, an assistant professor of medicine at Washington University School of Medicine in St. Louis (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.”
This process helps a cell quickly remove waste and clutter and begin the process of regenerating healthy tissue more rapidly than it would if the waste was removed slowly. But while cathartocytosis offers the benefit of being fast, there are drawbacks. Persistent carthocytosis, for example, can indicate chronic inflammation during an infection, and recurrent cell damage that can lead to cancer.
The researchers suggested that it may be possible to take advantage of this situation; tracking the cellular waste from cathartocytosis could offer a method for monitoring cancer.
Cathartocytosis was initially observed during another process called paligenosis, which is another response to injury that helps tissues regenerate. During paligenosis, injured cells are genetically reprogrammed to be more like stem cells that divide rapidly and restore tissue. It’s been thought that organelles called lysosomes were responsible for eliminating cellular waste in a slow process.
But the researchers saw debris outside of lysosome as well, and not even within cells. After seeing this repeatedly, they investigated with the mouse stomach injury model. This showed cells being reprogrammed quickly across many stomach cells, and the mass removal of cellular debris. This showed that the response was not incidental; it seemed to be an important part of healing.
Cells may use cathartocytosis during paligenosis, or they might apply cathartocytosis in more critical situations. Cells can regenerate tissue much faster with cathartocytosis, but may also lead to the accumulation of waste products that can cause inflammation.
More studies are now needed, but cathartocytosis could have other implications. The researchers suggested that the process may be promoting inflammation and injury in some gut infections.
“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.
Sources: WashU Medicine, Cell Reports