Hello, I'm Dr. Neal Schultz. And welcome to DermTV. Many of you know how passionate I am about the virtues of exfoliation. So yes… I’ll say it again… Exfoliation is the single most important therapeutic treatment you can do for your skin, whether for facial rejuvenation, acne control or prevention of precancerous growths. But... can exfoliation cause you to run out of skin? Well, consider this… The purpose of exfoliation is to remove accumulated excess old dead cells. This causes your skin to increase its production of new vibrant healthy cells which is technically called “increased epidermal cell turnover.” However, as many of you know, the Hayflick Limit says, "There's a limit to the number of times a fully differentiated human cell divides. And that limit is about 40 to 60 divisions or replications and applies to all human cell types that have been studied.” So this might make you think that you’ll eventually run out of skin cells, and exfoliation would then speed up this process. But here’s the catch! The Hayflick Limit only applies to fully differentiated cells… those are cells which are in their actual, final useful form, rather than in their potential future form. Stem cells by definition aren't fully differentiated, therefore they are an exception to the Hayflick Limit, and so they can continue to regenerate new cells for your entire lifespan, without limit. The importance of the constant regenerative effects of stem cells is most easily seen in tissues which must constantly produce replacements for existing cells, such as… you guessed it… The skin! Think of it another way. If the Hayflick Limit applied to skin, then at a certain age, skin scratches and cuts would no longer heal. Which as we all know, just never happens. So for more beautiful, healthier and younger looking skin, don’t worry about your skin “running out” and instead, exfoliate regularly!