The ability of a cell to divide and reproduce is essential to life and leads to the formation of complex single-cell organisms. It also allows used cells to be replaced from a limited number of “stem” cells, which then proliferate and specialize. However, in the case of cancer, cell proliferation is no longer controlled and becomes chaotic. Researchers from the GIGA Institute at the University of Liège have discovered that in a healthy individual, some of the immune cells in the blood, monocytes, also have this ability to multiply, with the goal of replacing tissue macrophages, which are essential for proper functioning. our body. This study has been published in Nature’s immunity.
The formation of complex multicellular organisms, to which humans belong, requires the generation of billions of cells from a finite number of progenitor cells that first proliferated and then acquired specific shapes and functions while assembling into tissues and organs. Our current knowledge indicates that most cells that make up an organism arise from so-called “stem” cells, which have been divided by a process called mitosis in order to produce a larger number of cells. These cells then stop reproducing to specialize, differentiate, and form muscles, brain, bone, immune cells, etc. When reproduction is not regulated properly, it can lead to the development of various diseases, among which cancers represent the most obvious example. In a study published in Nature’s immunityProfessor Thomas Marichal (Professor at ULiège, Wilbeo Research Fellow at the WEL Research Institute) and his team from the GIGA Institute at ULiège have discovered that this ability to proliferate is not only limited to stem cells, but is also a hitherto unknown function of immune blood cells, monocytes. In fact, blood monocytes, previously considered as differentiated cells, are able to multiply and form a group of monocytes in tissues in order to produce macrophages, important immune cells that protect us from microbes and support the proper functioning of our organs. .
“This is a major fundamental discovery, changing our understanding of the involvement of cell proliferation in the formation and maintenance of our immune system.” explains Thomas Marichal, director of the study. Our findings also suggest that the information that can be extracted from a blood mononuclear cell count, which is classically performed during a blood test, will reflect little of what is happening at the tissue level, during infection or inflammation, for example, as it can Monocytes reproduce when they enter tissues.” He also adds: “Fortunately, this reproduction is very well controlled and does not lead to a tumorigenic process. It has only one goal: to allow, as effectively as possible, to replace the immune cells that populate our tissues: macrophages. “