AP Biology class blog for discussing current research in Biology

Tag: healing wounds

Scraping Your Knee at 12:00am vs. Scraping Your Knee at 12:00pm: What’s the Difference?

By the time you reach the age of five, you’ve probably scraped your knee more times than you can count. Now, think back to the last time you fell off your bike or stubbed your toe during the day and the last time you did the same at night. Do you remember a difference? Chances are, you weren’t paying close enough attention, but there are scientists who were, and they have come to an interesting conclusion. According to a new study from England, nighttime injuries take longer to heal than daytime injuries, 60% longer to be exact! Why? It all has to do with the biological clock and the 24-hour cycle of cardiac rhythms of skin cells.

The Healing Process

Fibroblast skin cells are found in the deepest layer of the skin called the dermis. Check out the picture on the left for a close up view! When an injury occurs, fibroblasts travel to the surface of the skin, where their job is to synthesize and build the structural support of the new skin. How fast the fibroblasts travel to the surface depends on the time of day and the biological clock. Actin, a protein that forms the supportive structure of the cytoskeleton and gives a cell its shape, is the reason behind this difference. Ned Hoyle, a molecular biology researcher, studied the changes in actin over time, and came to the following conclusion: during the daytime, actin is in the form of long filaments, while at night, actin is in globular form. Actin filaments are crucial in helping cell moves, so when actin is in globular form, it takes longer for the fibroblast cells to travel to the surface of the skin.

The Evidence

The team of researchers conducted experiments on mice, which exhibited the same affect they had studied previously – the healing time at night is longer than during the day. Next, the team turned to humans, studying burn patients. From hospital records, they concluded that on average, burns that occurred during the day healed within 17 days, whereas burns that occurred at nigh healed within 28 days. However, there are still a lot of unknowns. Scientists predicted that the fibroblasts would make up for lost ground during the day, but in reality, the cells wounded during daytime never catch up.

What’s Next?

Although we can’t plan when we get hurt, this research is extremely important. Hoyle said that this research could be expanded to trying to make cells think its daytime, if a procedure takes place at night. Furthermore, he hopes to conduct more research on the complex process of healing and blood clotting. To check out their full study, click here!

Regular Cell Activity Could Help Heal Wounds


Photo taken by EMW

Photo taken by EMW

Biologists already know that flaws in metabolic processes in mitochondria (such as cell respiration) cause aging in many cells and tissues.  Now, they are exploring the converse situation.  Scientists from the Stem Cell Program and Boston Children’s Hospital are doing research to see if the trait that allows young animals to easily repair and regenerate their tissues can be produced in adult animals.  A protein called Lin28a (shown in image) is active in embryonic stem cells, and when scientists reactivated this protein (by reactivating the Lin28 gene) in older animals, the animals were able toregrow soft tissues (cartilage, bone, skin).  Lin28a promotes this regrowth partially by improving metabolism in mitochondria as it increases the production of enzymes involved in the making of energy.  As we learned in class, we need free energy to grow and create new cells. In this way, “Lin28a helps generate the energy needed to stimulate and grow new tissues”.  Essentially, the enhancing of the regular energy making process that the mitochondria perform could lead to advanced “regenerative treatments”.  (Click here for a graphical abstract of this study that helps to better understand the ideas behind the research.)

Additionally, experiments have been done that show that activity in the mitochondria can be enhanced without the stimulation of Lin28a.  This implies that a “healing cocktail” could be created pharmacologically.  I find it fascinating to see how cell processes, such as those that we learned about in class, can have such major implications for the future of regenerative medication.  Will they create new, more efficient drugs to help heal wounds?

Original Article


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