Zero risk of cosmetic surgery? Nature reveals the real secret behind "Rappi."

Introduction: The skin needs to be metabolized, repaired and regenerated to maintain normal life activity.
our skin is the largest organ in the body and the first line of defense to protect internal organs and tissues from external mechanical, chemical and physical damage.
skin, like other organs, needs constant metabolism, repair and regeneration to maintain normal life activity.
when the skin is severely damaged, cell growth factors or fibroblast growth factors can be used to promote cell migration and growth, thereby reducing scar formation.
, some beauty lovers remove scars through plastic surgery.
, skin can also be "pulled" through skin-pulling surgery to remove wrinkles and tighten the skin.
, what is the real mechanism behind being "pulled" like an elastic net? In a recent paper published in Nature by Professor Cédric Blanpain of the Stem Cell and Cancer Laboratory at the Free University of Brussels, Belgium, a study that found the plasticity and elasticity of the skin stem cells revealed for the first time the mechanisms by which the skin expands as it stretches, and is expected to use these mechanisms to promote wound healing or stimulate tissue expansion.
Doi:10.1038/s41586-020-2555-7 First, the team injected a self-inflating hydrogel under the skin of the mouse model to expand the skin.
this is like simulating that the rubber can contract under external forces, increasing the surface area by "pulling" the volume of the expanding hydrogel.
results showed that in the first two days after expansion, the mice's skin cell volume increased and the cell density decreased until it returned to steady state.
this suggests that the skin can perceive external pressures and adapt to them.
since the inflatable hydrogel promoted skin dilation, the researchers conducted a series of experiments on the differentiation of skin cells, skin dehydration, and skin inflammation.
found that the number of skin substrate cells expressing keratin 1 and 10 increased, the skin barrier was not damaged and inflammation did not affect the value added of skin cells.
suggests that during stretch-mediated skin dilation, a brief increase in the renewal and division of the skin stem cells maintains their cell composition, while the second generation of the skin stem cell progenitocytes tend to differentiate.
The second generation of progenitocytes was more likely to differentiate in order to further determine the role of the skin substrate cells in the "pull", and the team then used the most advanced genetic mice (Krt14-creer-RosaConfetti mice) to identify the cell fate of cloned cells of specific skin substrate cells, tracking their genetic lineage, marking stem cells at the top of the skin cell hierarchy, and tracking the fate of stem cell offspring over time.
found that only specific stem cells could react to "pulling", changing their behavior and cell fate.
Clone analysis of skin stem cells during skin expansion, the team identified the molecular markers of these specific stretched skin stem cells and key genes, paths, and cell substrates isolated by fluid cell fluorescence substrates using three high-flux analysis methods: DNA Microarray, ATAC-seq, and single-cell RNA sequencing.
results show that there is a heterogeneic reaction of substrate cells to "pulling", i.e. the state of the cells inside the substrate is not the same under the mechanical force.
The molecular regulatory mechanisms of skin dilation, the study is the first to reveal how the skin reacts mechanically by activating stem cells from specific groups, as well as the discovery of molecular markers that play a key role in the skin or links to some cancer signaling molecules.
, of course, this study only opens the door for us to learn about "pull", and there are many more biomedical mysteries waiting to be learned.
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