Scientists Discover Massacre: "Killer" Cells Kill Innocent Cells

The scientists found that a quarter of the progenitor cells in the testes were “killed” by phagocytes, despite the fact that these cells weren’t doing anything “wrong.”

University of Haifa research has identified killer cells.

A process involving the “killing” of newly generated living cells has been discovered for the first time in a recent study conducted at the University of Haifa. Research, described in a respectable journal Science Advancesfound that during the process of cellular differentiation in fruit flies, phagocytic cells consume and destroy healthy living cells.

“We found that phagocytes can function as ‘killers.’ It is known that phagocytic cells engulf and dissolve dead cells, but we demonstrated for the first time that they also kill newly created normal cells. Basically we have characterized a novel mechanism of cell death. The more we know the mechanisms of cell death, the better we understand how to treat various diseases, especially cancer,” explains Professor Hilla Toledano, head of the Department of Human Biology at the University of Haifa and author of the study.

The origin of some body tissues, including skin, hair, stomach, and testes, can be traced back to stem cells. By continuously supplying new cells to replace old ones, these powerful stem cells enable tissue replenishment. Each stem cell in this process divides into two cells, one of which is stored for future use and the other develops to replace the cells lost in the tissues.

In the current investigation, Professor Toledano, Professor Estee Kurant, and a group of scientists from the University of Haifa looked at the sex cells of fruit flies. Since many molecular processes in fruit flies and humans are similar, they can be used as effective models in this situation.

The study of fruit flies is useful because of the capacity to monitor processes in living tissue and the simplicity of genetic changes, which allows for the precise identification of cellular processes. Six Nobel Prizes have been awarded over the years to scientists who discovered biological mechanisms in fruit flies conserved in humans.

As previously mentioned, the division of a stem cell into two cells—a stem cell and a cell known as a progenitor—starts the process of sperm differentiation in male fruit flies. This process continues until functional sperm are formed. Researchers already know that a quarter of these progenitor cells perish and don’t develop into sperm from previous studies. The goal of the study was to better understand what happens to these cells.

The body has an established and important mechanism called cell death. Under normal circumstances, cells have the ability to “suicide” when severe mutations have occurred or after they have fulfilled their purpose. Phagocytes come to “eat” the dying cells, effectively taking their contents and dissolving them. It is known that phagocytes sometimes “eat” cells of the immune system that have completed their task of defending the body against intruders.

In the current study, the researchers found that phagocytes “killed” a quarter of the progenitor cells in the testes even though these cells were doing nothing “wrong” and were only in the process of differentiation; they are still new cells and they are not abnormal in any way.

In the first stage, the researchers prevented the ability to eat phagocytes and found no dead cells in the tissue. In other words, phagocytes are responsible for the death of progenitor cells.

In the second stage, the researchers used real-time imaging to monitor living tissue and found that the progenitor cells were engulfed alive by phagocytes, and only then did the death process begin. “We discovered for the first time a process that involves the ‘killing’ of completely normal cells. We still don’t know why this happened. Perhaps this process aims to supply nutrients to maintain a functional population of stem cells throughout the life of the organism” suggests Professor Toledano.

In addition to understanding new mechanisms, this research could contribute to our ability to develop drugs and means to control cell death, and in particular, of course, to treat cancer. “Tumors are characterized by constant growth and disruption of the natural process of cell death. If we can successfully introduce phagocytes in this process capable of eliminating live cancer cells, we will be able to control tumor growth. The more we learn about the mechanisms of cell death, the better we can take advantage of this process to get rid of cancer cells,” concludes Professor Toledano.

Reference: “Phagocyte cyst cells in Drosophila testes eliminate germ cell progenitors through phagoptosis” by Maayan Zohar-Fux, Aya Ben-Hamo-Arad, Tal Arad, Marina Volin, Boris Shklyar, Ketty Hakim-Mishnaevski, Lilach Porat-Kuperstein, Estee Kurant and Hila Toledano, June 17, 2022, Advances in Science.
DOI: 10.1126/sciadv.abm4937

#Scientists #Discover #Massacre #Killer #Cells #Kill #Innocent #Cells