Now we are going to dive deeper into the process of aging – cell senescence and what that means for our skin!
We already know (and as is constantly drilled into our brains) that protecting our skin from the sun is vital to help prevent our skin from aging prematurely. But there is no way to stop the natural factors of aging, no matter how much we protect ourselves our skin will look different over time.
The inevitable changes of aging occur mostly in the dermis. The dermis is located directly beneath the epidermis and contains blood vessels, hair follicles, sweat glands and various cell types surrounded by collagen, elastin and extracellular matrix proteins. Fibroblasts are also located here, the cells responsible for producing extracellular matrix proteins along with collagen and elastin. As we age the activity of fibroblasts decreases as they become senescent, which limits their ability to synthesize these fibres and proteins. Their ability to properly organize fibres in the tissue is also compromised, which results in improper crosslinking of fibres and wrinkle formation.
UV exposure exacerbates the breakdown of dermal tissue. Matrix metalloproteinase (MMP) is an enzyme which breaks down collagen and elastin fibres in order for tissue to be maintained and remodeled when needed. However, with UVB exposure the activity of MMP is heightened, which results in an excess breakdown of these fibres. Long-term exposure of UVB, combined with compromised fibroblast activity is the perfect recipe for loss of dermal tissue integrity, and wrinkle formation.
Loss of tissue elasticity due to collagen and elastin breakdown is not the only thing happening in the dermis. As I said, fibroblasts are responsible for synthesizing extracellular matrix proteins. Glycosaminoglycans (GAGs), the most commonly known one being hyaluronic acid, are special molecules which have a fantastic ability to hold water. They keep our skin hydrated and plump, which helps protect our skin from injury. But as those fibroblasts become senescent, their ability to produce GAGs also decreases, along with their proper distribution in the dermis.
Keeping this loss of GAGs in mind we are going to quickly go up to the epidermis. In the deepest layer of the epidermis, there lies stem cells which are responsible for cell-turnover, providing fresh layers of cells which slough off over time (this process is called desquamation). As we age, the activity of these stem cells can decrease up to 30%. This means that over time, our cell-turnover time is increased and fewer fresh cells are produced, which then impacts the desquamation that keeps our skin looking smooth and fresh. This compromised cell-turnover is what leads to a compromised skin barrier, causing our skin to appear thin, dull and rough.
If our skin barrier is compromised this means that we are more susceptible to injury and water loss. Going back to GAGs, we know that as we age we have a decreased ability to hold water in our dermis. Combine this compromised ability to hold water in the dermis, with a compromised epidermal barrier to prevent water loss, you have skin which is extremely susceptible to dehydration. Dehydrated skin looks less full, and contributes to deep wrinkle formation.
All these changes occur when specific biochemical changes take place. As these changes become identified with further research, we will be able to counteract the effects of aging in targeted, efficient ways. The development of cosmetic ingredients will continue to grow to reflect new knowledge of skin physiology, and this way we can create effective skin care products.
Please feel free to contact us with any questions you have about this blog!
Skin Management System by Dr. Strauss
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