Danne: all about skin permeability

Danne Montague-King, Doctor of Biochemistry and Pharmacology, founder of DMK (USA)

When trying to “cure” aging skin, we often use a stick rather than a carrot, turning to negative stimulation methods and subjecting it to stress tests. Unfortunately, this is not the most effective method, as I have definitely learned over the years of working closely with skin. There are much more effective and delicate methods of influence, and that is what I have focused my activities on.

Our skin is an amazing organ. However, contrary to popular beliefs, it is not the biggest - this title should be given to the fascia. Yes, for many this statement will seem controversial - and not because of the size of the fascia (it really is everywhere in the body), but because of whether it is an organ. My answer is unequivocal: of course, it is, and an organ that functions in a very complex way. And I will gladly have the honor of lobbying the medical community for the inclusion of fascia in the anatomy of the body as an organ. By the way, all cosmetic procedures that affect deep tissues actually affect not only the skin, but also the fascia.

However, the skin is not a layer cake, as it is usually portrayed in textbooks. This representation is nothing more than a sketch. What leads us to the myth of skin layers is the complex structure of the epidermis with its key ability to prevent foreign substances from penetrating the skin.

The outer stratum corneum, stratum corneum, is the main protective barrier of our body, and, I must say, an excellent barrier! Composed of dead keratinocytes and an accumulation of various fats and waxes, the stratum corneum acts as a defense against excess external moisture, chemicals, radiation, and the ever-changing bacterial load that attacks us daily. The functioning of the stratum corneum is easy to visualize by imagining the following situation: when we sit in water for too long, the skin becomes wrinkled because the dead cells of the stratum corneum, like little sponges, are saturated with water, and as soon as the water evaporates, the skin takes on its normal appearance. That is, not everything that is topically applied to the skin penetrates its deep layers or is completely absorbed by the body, otherwise we would swell up like wet sponges in a bathtub!

However, despite the powerful protective barrier provided by the skin, some chemicals are able to penetrate into and through the body. Whether these substances can harm us depends on the dosage and how they behave when ingested: for example, if they are harmful, we have “immune guards” who will show these criminals the way out.

There is a huge difference between penetration and absorption, where the concentration of the chemical is important. There are many variables that affect the rate or potential of penetration and absorption. These include the structure of the chemical being applied, the method of delivery, the area of skin to which it is applied (thin skin is more susceptible to penetration than thick skin), and its condition (impaired barrier properties also increase penetration).

IF THE EPIDERMIS IS PRACTICALLY IMPREMONABLE, THEN HOW DO WE AFFECT THE SKIN?

Skin pores can be natural reservoirs for storing huge amounts of substances (provided that these substances are “formulated” transdermally - for example, topical hormone replacement therapy drugs or nicotine patches for smokers). Yes, this type of formulation takes a lot of time and includes a lot of fractionated lipids and proteins that require wetting agents, but then the necessary ingredients are stored in the pores and, as needed and depending on the level of absorption by the body, are washed into the deep layers of the epidermis in a network-like structure sebaceous glands, and this can happen over a long period of time. In this case, any “bad” substance will trigger immune defense and, ideally, will be rejected and pushed out.

Transepidermal penetration can also be increased by physical factors such as heat and cold (pseudo-heat and cryotherapy), which send signals to the skin to wake up or respond in a specific way by increasing circulation. In these cases, the skin's systems activate their memory banks and begin to act in the same way as when the skin was young and at the peak of health. Toxins are eliminated, bacterial attacks are blocked, and enzymes present in the skin are naturally activated and perform their functions better.

WHAT ABOUT EXFOLIATION?

The stratum corneum is not completely dead. It does have a limited form of metabolic activity. It also acts as a biosensor, signaling the underlying epidermis to respond to external stressors such as exfoliation, cavitation, peels and enzymes.

However, a delicate balance between basal cell proliferation and corneocyte exfoliation must always be struck when attempting to remove dead skin cells. A constant protective thickness of the epidermis must be maintained! This is why I have never believed in aggressive procedures, be they mechanical or chemical. Popular thesis: “Let's aggressively attack the skin so new collagen can form!” – is an absurd practice. After all, although the skin may look more elastic after such an impact, this is a temporary effect, which, in fact, is a healing phase. And after a year, a real picture of “rejuvenation” will appear in the form of hyperpigmentation, loss of tone, decreased elasticity, or even hypopigmentation, which will begin to appear due to the depletion of protective mechanisms that are at work 24 hours a day, 7 days a week.

At this stage, the patient stops coming to you and looks for a plastic surgeon, goes crazy with fillers, or even exposes himself to even greater attacks from various devices, rollers and other new anti-age tricks that only keep the body's immune systems in an activated state for a long time. time.

OSMOSIS - THE STAR OF TRANSEPIDERMAL DELIVERY?

In cosmetology, osmosis has come to the fore in recent years. But what does this concept mean (if it really means something?) when applying a drug topically, say, in the form of a cream?

The ability to create osmotic pressure is the main colligative property of any solution. In order for the cell to receive water by osmosis, the substance used must be hypotonic, that is, have a lower concentration of a substance that does not penetrate the cell membrane. In this case, the level of cell hydration increases. An isotonic environment implies exactly the same concentration of water as the cell, without any systemic movement through the cell: water molecules diffuse across the cell membrane in equal amounts in and out, without accumulating in the cell or being lost by it. If the concentration is higher than in the cell (hypertonic solution), the cell will become dehydrated.

To be honest, I can't imagine a cream or even a spray that would be so chemically tuned to achieve this kind of homeostasis. However, I love a challenge and am currently working on a water mixture that will be 10 times wetter than water and help achieve this osmotic effect in reality.

Reverse osmosis is a more viable approach in skin treatments: it involves applying pulsating pressure to the skin over a period of time to increase the permeability of cell membranes. In this process, the used solute is retained on one side of the membrane, and the pure solvent passes to the other side, causing intercellular fluids to move from areas of high pressure to areas of low, thereby removing impurities, toxins, etc.

So far, as far as I know, in cosmetology this effect can only be achieved with the help of enzymes, applying them to the skin in the form of a mask, which keeps the tissues in stasis for about an hour thanks to a pulsating mechanism. This pulsation creates a period of rest between pulses, which leads to a reverse osmosis effect in which peripheral capillaries dilate slightly, blood flow and oxygen delivery to the cell mitochondria (the battery that supplies energy to the cell, like a power plant) is improved, and additional toxins are removed from the cell area and surroundings. their extracellular matrix.

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The fundamental systems of the skin must be understood and learned to respect. We must find out what is needed to replace a broken part, whether the skin's own chemistry matches the nutrients we are trying to support it with. It is necessary to use not brute force, but stimuli that will awaken and activate the skin's natural ability to heal and maintain homeostasis.

You can always find adequate ways to penetrate the skin. There are not many of them, but they exist. The main thing is to use the right delivery mechanisms. And no loud advertising promises, no matter how highly scientific they may sound, will change this. Over many years of work, I realized that my main laboratory is the human body. And he always - I emphasize: always! – tells me what I can do and what I can’t do.

First published in Les Nouvelles Esthetiques 2015/№2