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Our internal clock affects wound healing
If people suffer from a skin injury, it could make a difference in healing at what time of day the wound occurred. British experts have now found that actin production and fibroblast motility change rhythmically throughout the day. The biological activity is influenced by the internal clock. In other words, the duration of a healing process is also determined by the time of day the wound was created.
Scientists at the University of Manchester and the Medical Research Council at Cambridge found that skin wounds are affected by the time that the wound occurred. The doctors published the results of their study in the journal "Science Translational Medicine".
Biological activity of the connective tissue cells changes during the day
The time of day determines how quickly skin injuries heal. Depending on the time of day, a skin wound can heal up to twice faster, influenced by the production of actin and the mobility of fibroblasts. Fibroblasts are so-called mobile connective tissue cells. They play an important role when it comes to healing skin injuries. However, the biological activity of the connective tissue cells changes over the course of the day, the researchers say.
Will wound healing be significantly improved in the future?
In their investigation, the scientists discovered that fibroblasts from mice produce more actin during the waking phase of the animals compared to the resting phase. The experts explain that actin is a protein that enables cells to migrate into the injured tissue. It also affects the formation of solid cell contacts. Based on the current study results, the wound healing of patients after surgery could be significantly improved in the future.
Did evolution lead to improved wound healing during the day?
The internal clock in every single skin cell influences how effectively the cells react to injuries that have occurred, explains author John O'Neill from the Medical Research Council in Cambridge. Human evolution may have caused existing injuries to heal faster during the day than at night. This could be due to the fact that the risk of injuries is greater during the day, the expert adds.
Effects of the internal clock
An internal clock is ticking in all cells in the human body. Such clocks are synchronized by special brain cells. This leads to the fact that the wake-sleep rhythm adapts to the natural day-night change. In addition, each organ of the body also develops its own so-called circadian rhythm of its function, the experts explain. Such daily rhythms are influenced by special genes, the activity of which changes during the day. Activity rises and falls regularly within 24 hours. This also affects the concentrations of the proteins encoded by these genes. The resulting fluctuations also affect other metabolic products, the scientists add.
Experts examined 1608 proteins
With the help of cell cultures, the British researchers investigated which proteins are produced in the fibroblasts of mice every day. The doctors examined a total of 1608 identified proteins. A so-called circadian rhythm was found in 237 of the proteins examined. Several of these proteins are involved in the formation of the cytoskeleton. This consists of thread-like molecular assemblies that give the cell its strength and mobility. A major part of this cell structure is actin. During the waking phase of mice (at night), the fibroblasts produced more actin than during the day. This rhythm was also retained in the so-called cell culture. Therefore it cannot be controlled by other factors of the living animal.
Phase of increased actin production accelerates wound healing
Changes that could affect the efficiency of wound healing during the course of the day were analyzed by the experts using three different methods. They examined cultures with locally destroyed cell layers. In addition, cultures of skin tissue into which holes had previously been punched were examined, and finally there was also a study that was carried out on living mice with an existing cut, the authors explain. The same result was found in all investigations, and wound healing accelerated in the phase of increased actin production.
Burn wounds at night take longer to heal
The scientists checked the connection by analyzing the medical data of a total of 118 burned patients. It was found that burns caused at night take a longer time to heal. Such a healing of the burn took an average of 60 percent more time than if this connection had been created during the day, the doctors explain.
More research is needed
If the wounds developed at night, 95 percent healing took 28 days. On the other hand, if the wounds were created during the day, healing only took 17 days. Healing wounds as quickly as possible is clinically relevant because faster healing reduces the risk of infection and chronic wound healing disorders. Through further investigations of the effects of the internal clock on wound healing, active ingredients could be developed in the future that can significantly improve the healing success. (as)