Genes in skin wound healing: microRNAs 1

Published on October 7, 2014   33 min
0:00
Hello, I'm Chandan Sen, a Professor at The Ohio State University Wexner Medical Center. I direct the Comprehensive Wound Center at Ohio State, and also direct the Center for Regenerative Medicine and Cell-Based Therapies.
0:18
Today I'm going to address the overall topic of genes in skin wound healing. And in particular, I will be addressing the significance of non-coding genes, and the microRNA component of non-coding genes. To a common person, when we talk about wounds, the first thing that comes to mind are nicks and cuts, lacerations that can be caused by some traumatic injury or accident, abrasions. But if these types of wounds happen to a healthy human we expect closure in a reasonable time frame. And if this is happening in an adult this type of closure of wound usually is a associated with a scar response. As long as the skin is kept cleaned and the wound is kept cleaned these types of wounds are not expected to be complicated in a healthy human.
1:14
There are various ways of closing a wound. It could be primary intention, where the wound is closed with suture material. It could be secondary intention, in which the wound is left open and closes naturally without the use of any suture material or such. Finally, it could be tertiary intention where the wound was left open to heal by secondary intention, and when it did not, another mechanism of closing it was adopted. In this case it must be made sure that the wound is clean prior to it being closed.
1:50
Although wounds in healthy adults close predictably and without any complication, wound closure is substantially complicated in people with several types of illness, such as immune compromised conditions, malnutrition, obesity, diabetes, and a host of other conditions. At present, the inability to close problem wounds represents a major problem in health care in the United States. We have over six million people suffering from chronic wounds. It's a substantial cost burden to society. At this time, the number of people suffering from diabetes in the country is sharply rising. And 5% of people affected with diabetes will develop foot ulcer. And interestingly, 10% to 30% of folks with diabetic foot ulcers require amputation. Amputations are crippling for the society, not only for the individual whose productivity substantially goes down, but also for society where the cost is heavy.
2:57
Once we have a wound on the human skin, the healing process can be broadly classified into different phases. Although these phases are not distinct in their overlapping portions. Immediately after the injury there's hemostasis, where there's blood clot so that the blood flow out of the body is stopped. And as soon as this clot process completes, we mount inflammatory process. And inflammatory cells are dropped through the blood into the wound site. This process of recruiting inflammatory cells into the wound site is actually meant to be supporting the healing process. As long as the inflammation is mounted in time, and resolved in time. As the inflammatory process resolves we see a bolstering of the proliferation process, or phase, during which time fibroblasts keratinocytes start proliferating and prepare to migrate. At the same time, the edges of the wound are now lined by myofibroblasts, which are taught to be primarily derived from fibroblasts. And these myofibroblasts have contractile properties that help in the so-called purse-string-like-contraction contraction of the open wound. As this process happens and the fibroblasts proliferate, there is also the process of maturation that gradually started with the laying of collagen, primarily contributed by fibroblasts. The process of maturation is a long one and this could span from days to years, depending on the type of wound. Once the wound is closed, the scar process is also in a phase of dynamic remodeling that continues for years after the wound has been closed.
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Genes in skin wound healing: microRNAs 1

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