Ageless Aesthetic Institute (courses in current skin procedures).
Companies: DermTech (noninvasive sticker for pealing off skin cells for meloma diagnosis)
See also Skin Disorders under Diseases & Disorders
Introduction:
The term “skin” refers to the outer protective covering of the body, consisting of the corium and the epidermis, including sweat and sebaceous glands, as well as hair follicle structures. Skin and oral musosae as well are composed to two primary layers, the outer epidermis, which is stratified epithelial tissue mainly composed of multiple layers of keratinocytes and the dermis, which is the layer beneath the epidermis consisting of connective tissue, blood vessel, immune cells, collagen and other components. Like the intestine, the epidermis of skin and oral musoca are self-renewing. The layers of the epidermis reflect the stages along the continuous process of keratinocyte maturation, from the basal layer adjacent the dermis which contains the proliferating stem and progenitor cells, to the outer protective layer of dead, cornified keratinocytes which are being sloughed form the surface. The cell division that occurs in the basal layer of the epidermis provides a continous source of keratinocytes which fully replenish the epidermis at rates that are estimated to be up to several weeks.
The skin, together with the hair, nails and sweat and oil glands, forms the integument.
Topical corticosteroids are an essential tool for treating inflammatory skin conditions such as psoriasis and atopic dermatitis. Topical corticosteroids are classified by strength and the risk of adverse effects such as atrophy, striae, rosacea, telangiectasias, purpura, and other cutaneous and systemic reactions. The risk of adverse effects increases with prolonged use, a large area of application, higher potency, occlusion, and application to areas of thinner skin such as the face and genitals. The quantity of corticosteroid prescribed depends on the duration of treatment, the frequency of application, the skin location, and the total surface area treated. Correct patient application is critical to successful use. (McEleney, “Topical Corticosteroids: Choice and Application” Am Fam Physician. 2021;103(6):337-343).
Layers of the Skin and Composition:
Ceramides are a class of lipids (fats) that occur naturally in the human skin, making up about 50% of the skin’s intercellular lipids. There are at least 12 different types of ceramides found in the skin (e.g., Ceramide NP, AP, EOP), each with a slightly different structure based on its specific sphingoid base and fatty acid chain length. They are essential for maintaining the skin’s structural integrity, acting as the “grout” between skin cells to form a protective, water-retaining barrier. They are “skin-identical” ingredients and highly effective in reinforcing the natural skin barrier.
–Ceramide PC-104 (N-(3-hexadecyloxy-2-hydroxypropyl)-N-2-hydroxyethyl hexadecanamide): is a synthetic pseudoceramide designed to mimic the function of natural ceramides in the skin. The primary difference is its origin and specific chemical structure, which offer better formulation stability and cost-effectiveness compared to some natural or animal-derived ceramides. It is synthetically manufactured, though its components may be derived from natural fatty acids.
Epidermis: refers to the outermost and novascular layer of the skin, derived from the embryonic ectoderm, varying in thickness from 0.07-1.4 mm. The epidermis is a complex epithelial tissue containing keratinocytes that are proliferating, differentiating and desquamating, and is stratified such that morphological functional changes in the keratinocytes occur in an orderly progression. The normal epidermis is maintained in a dynamic steady state as proliferation of keratinocytes continually compensates for the loss of cells which are shed from the surface of the skin. Within the epidermis, proliferation takes place in the basal layer of keratinocytes that are attached to the underlying basement membrane, and cells undergo differentiation as they migrate through the suprabasal layers, finally being shed from the tissue surface as dead, cornified squames. Three subpopulations of basal keratinocytes have been defined by cell kinetic analysis: stem cells, transit-ampliyfing cells, and committed cells.
Skin cells which make up the epidermis include Merkel cells, keratinocytes, melanocytes and Langerhans cells.
The human epidermis is a pluristratified tissue made up of basal, spinous, granular, upper-granular and cornified layers, in ascending order. The keratinocytes in the basal layer express keratins K5 and K14, as well as K15, which are then substituted by markers of epidermal differentiation such as K1, K10, IVL in the spinous layer. With progression of differentiation, other markers such as FLG and loricrin are expressed in the granular layer. The keratinocytes at the level of the cornified layer are called corneocytes as they are devoid of organelles and nuclei and are finally sloughed off.
–Keratinocytes: Keratinocytes, which are the main cell type in the epidermis, are subject to cycles of proliferation, differentiation and death that allow preservation of epidermal homeostasis as well as of epidermal barrier function. They maintain their proliferative capacity in the basal epidermal layer and when starting to differentiate they cease dividing and move to occupy the suprabasal spinous, granular, upper-granular and cornified layers. In the suprabasal layers, the keratinocytes express markers of terminal differentiation, until they ultimately loose nuclei and organelles and become corneocytes. Corneocytes are essentially bundles of filaments surrounded by cross-linked proteins and insoluble lipids and are ultimately shed out as dead cells. Among the proteins that keratinocytes express during the distinct stages of differentiation, there are keratins, which are usually organised in heterodimers to constitute the keratin intermediate filaments (KIFs) that extend from the cell nucleus to the cell-cell desmosomes junctions.
The keratinocytes, which are the main cell type in the epidermis, are subject to cycles of proliferation, differentiation and death that allow preservation of epidermal homeostasis as well as of epidermal barrier function. They maintain their proliferative capacity in the basal epidermal layer and when starting to differentiate they cease dividing and move to occupy the suprabasal spinous, granular, upper-granular and cornified layers. In the suprabasal layers, the keratinocytes express markers of terminal differentiation, until they ultimately loose nuclei and organelles and become corneocytes. Corneocytes are essentially bundles of filaments surrounded by cross-linked proteins and insoluble lipids and are ultimately shed out as dead cells.
Among the proteins that keratinocytes express during the distinct stages of differentiation, there are keratins, which are usually organized in heterodimers to constitute the keratin intermediate filaments (KIFs) that extend from the cell nucleus to the cell-cell desmosomes junctions. The basal keratinocytes typically express keratin 5 (K5) and 14 (K14). With differentiation, K5 and 14 are replaced by K1 and K10 and other “specialised” keratins such as K9 in the palms and soles’ skin and K2 in thickened skin areas. Keratin 15 (K15), which in the hair follicles (HFs) is associated with bulge stem cells, is also expressed by undifferentiated keratinocytes and lost when keratinocytes differentiate. Other proteins that mark epidermal terminal differentiation include, but are not limited to, involucrin (IVL), loricrin, filaggrin (FLG), trichohyalin (TCHH) and small proline-rich proteins (SPRRs).
Dermal-epidermal Junction (DEJ): is a critical component of the skin and is composed of a netword of structural proteins that provide a firm connection between the basal keratiocytes of the epidermis and the dermis. This structural network is made up of (1) the hemidesmosome-anchoring filament complex; (2) the basement membrane comprising two layers, the lamina lucida and the lamin densa and (3) anchoring fibrils.
Corium or Dermis: refers to the layer of the skin deep to the epidermis, consisting of a dense bed of fascular connective tissue, and containing the nerves and terminal organs of sensation. The hair roots (follicles), and sebaceous and sweat glands are structures which are also embedded in the dermis.
The dermis is a rich matrix of fibroblast cells and fibers such collagen, and it contains macrophages and mast cells. The dermis also habors a dense network fo nevers, blood vessels, and lymphatic vessels. Damage to the epidermis generally does not result in bleeding, whereas damage deep enough to penetrate the dermis results in broken blood vessels.
Sebaceious (oil) glands and scent glands are associated with the hair follicle. All of these glands have opening on the surface of the skin, so they pass through the epidermis as well. The sebasceous glands secretion, celld sebum, has a low pH, hwicch makes the skin inhospitable to many microorganisms. Sebum is oily due to its high concentraiton of lipids. The lipids can serve as nutrients for normal microbiota, but breakdown of the fatty acids contained in lipids, leads to toxic by products that inhibit the growth of microorgansms not adapted to the skin environment. Lysozyme is an enzyme found in sweat (and tears and saliva) that specifically breaks down peptidoglycan, found in bacterial cell walls.
Blister fromation, the result of friction trauma or burns, represents a separation between the dermis and epidermis.
Acne:
Antiacne agents may be used to treat blemishes, pimples, blackheads, and whiteheads. Exemplary anti-acne agents include but are not limited to salicylic acid, benzoyl peroxide, or sulfur, and their derivatives and combinations.
Age Spots:
As the skin ages, the division rate of skin cells slows down causing an overall reduction in the number of cells and blood vessels that supply nutrients and other necessary building blocks for the skin resulting in a decrease in the thickness of the epidermis. Collagen and elastin fibers in the underlying layers of skin which provide the scaffolding for the surface layers begin to weakn and deteriorate.
Products with retinoids, alpha-hydroxy acids, azaleic acid, hydroquinone, kojic acid, salicylic acid as active agredients have all shown to make the skin appear younger.
Hydroquinone, an over-the-counter drug that can bleach your skin, may fade dark spots. Retinoids may make your skin tone more even. One study says vitamin C helps fade age spots when you use it for 12 weeks. Kojic acid — a chemical that’s often used as an skin-whitening ingredient in products — can also help with age spots.
Dandruff:
Antidandruff agents may be used to treat dandruff, seborrheic dermatitis, or psoriasis. Exemplary antidandruff agents include but are not limited to the following: coal tar, salicylic acid, selenium sulfide, sulfur, zinc pyrithione, and their derivatives and combinations.
Contact Dermatitis (see skin disorders)
Atopic dermatitis (Eczema): (see outline)
Psoriasis: (See outline under Skin Disorders)
Psoriasis is more than dry skin. It’s caused when the immune system misfires and speeds up skin cell growth. Dry air, lack of sunlight, and colder weather can make it worse. Follow tips for dry skin: short, lukewarm showers, lots of moisturizer, and humidifiers throughout the house. Ask your dermatologist about phototherapy, which uses ultraviolet light B (UVB) rays to slow the growth of skin cells, and about the best treatments for you.
Bacterial Infections:
Antimicrobial agents include agents that kill microorganisms or prevent or inhibit microorganism growth and reproduction or agents that help prevent infection in minor cuts, scrapes, and bums. Exemplary antimicrobial agents include calcium lactate, dimethyl MEA, gallic acid, lens esculenta (lentil) seed extract, potassium alum, sodium alum, sodium aluminum chlorohydroxy lactate, sodium aluminum lactate, tannic acid, tioxolone, tranexamic acid, zinc acetate, zinc chloride, zinc lactate, zinc phenolsulfonate, zinc sulfate, zirconium chlorohydrate, witch hazel, and their derivatives but are not limited to the following: lower chain (C and combinations. 1 -C4 ) alcohols, quaternary ammonium compounds such as benzalkonium chloride and benzethonium chloride, clindamycin, methylbenzethonium chloride, hydrogen peroxide, Oligopeptide-10, phenols, tea tree oil, triclosan, povidone-iodine 50 (PVP-Iodine), and their derivatives and combinations
Fungus:
Antifungal agents include agents that inhibit the growth and reproduction of fungal cells or decreases the number of fungi present. Exemplary antifungal agents include but are not limited to the following: calcium undecylenate, ketoconazol, povidone-iodine (PVP-iodine), tea tree oil, undecylenic acid, zinc undecylenate, and their derivatives and combinations.
Particular Regions of the Skin
Face/Body:
–Washing/Shower: Choose a gentle, super-fatted, fragrance-free soap — bar or liquid — for cleansing. Super-fatted means the soap is loaded with oils. If skin is dry, moisturizers that contain urea, dimethicone, glycerin, lanolin, or mineral oil can be good bets.
Humectants — like urea, glycerin, hyaluronic acid, propylene glycol — absorb water from the air. They are oil-free. Emollients — like baby or mineral oil, plant oils (like jojoba oil), petroleum jelly, lanolin, stearic acid — help replace oils in the skin. Many moisturizers contain a combination. You may want to skip some anti-aging moisturizers in winter. Those that contain retinoids can further irritate already dry, sensitive skin.
–After Shower:
Ointments — like petroleum jelly — have more oil than creams or lotions. That makes them more greasy, too, so they may be best for feet and body. Minimize the greasy feeling by using a very small amount and gently but thoroughly rubbing it into skin. Apply after a warm shower.
Right after you step out of the tub, pat skin dry and apply moisturizer to retain the water your skin just absorbed. A glycerin– or hyaluronic acid-based moisturizer can increase the amount of water that’s drawn into your skin. Baby oil (mineral oil) is also a good choice, because it prevents water from evaporating from your skin. Don’t stop there: Liberally re-apply moisturizer throughout the day, especially to troublesome dry skin patches.
To get the most out of your moisturizer, exfoliate. Clearing away dead skin cells lets a moisturizer better penetrate dry skin. Exfoliate gently with a moisturizer that contains lactic acid or salicylic acid. Some exfoliants can be irritating, especially in winter, so try them on a small patch of skin first. If your skin is really dry or irritated, ask your doctor before starting a new skin care product or regimen.
If its cold outside and you have the heat on, dry air can mean parched, dry skin. Use a humidifier to restore moisture to the air. You can find inexpensive models at most drug stores. Put one in your bedroom; better yet, invest in two or three and place them strategically around your home to stave off irritated, itchy skin this winter.
Apply sunscreen if you will be outside, even in cold climates. Skiers and other winter athletes are at special risk of sunburn because snow reflects sunlight. In fact, it bounces 80% of the sun’s rays back to us, compared to less than 20% for sand and surf. Even if you’re not hitting the slopes, you still need the protection of a sunscreen with an SPF of 30 or more. Apply daily, and reapply at least every two hours if you’re outside.
Feet: Mature skin makes less oil and elastin, which leaves it drier and less supple. Without regular care, your heels may harden, crack, or hurt. Special creams called keratolytics help slough off the tough top layer. Follow up with a pumice stone to remove dead skin.
Cleansing; Removal of Dead Skin Cells:
Cleansers include agents that are used for cleaning the skin and hair by solubilizing oil and suspending soils. Cleansers may be foaming or non-foaming. Exemplary cleaners are typically a surfactant and can be characterized as nonionic, anionic, or zwitterionic. (Rodan, US 9,144,434)
–Nonionic surfactants are generally characterized by the presence of an organic hydrophobic group and an organic hydrophilic group. The length of the hydrophilic moiety can be readily adjusted to yield a water dispersible or water soluble compound having the desired degree of balance between hydrophilic and hydrophobic properties.
–Anionic surfactants includes those with a negative charge on the hydrophobic group or surfactants in which the hydrophobic section of the molecule carries no charge unless the pH is elevated to neutrality or above (e.g. carboxylic acids). Carboxylate, sulfonate, sulfate and phosphate are the polar (hydrophilic) solubilizing groups found in anionic surfactants. Cations (counter ions) associated with these polar groups include sodium, lithium, potassium, animonium, substituted ammonium, calcium, barium, and magnesium. (Rodan, US 9,144,434)
–-Zwitterionic surfactants generally contain cationic and anionic groups which ionize to a nearly equal degree.
Abrasives may be used to remove unwanted skin such as dead skin cells and calluses. Exemplary abrasives include but ditridecyl thiodipropionate, dodecyl gallate, dunaliella salina extract, erythorbic acid, ethyl ferulate, ferulic acid, hydroquinone, p-hydroxyanisole, hydroxylamine HCI, hydroxylamine sulfate, hydroxytyrosol, isooctyl thioglycolate, isoquercitrin, kojic acid, madecassicoside, magnesium ascorbate, magnesium ascorbyl phosphate, melatonin, methoxy-PEG-7 rutinyl succinate, methylene di-t-butylcresol, methylsilanol ascorbate, nordihydroguaiaretic acid, octylgallate, phenylthioglycloic acid, phloroglucinol, potassium ascorbyl tocopheryl phosphate, potassium sulfite, propyl gallate, resveratrol, rosmarinic acid, rutin, sirtunis, sodium ascorbate, sodium ascorbyl/cholesteryl phosphate, sodium bisulfite, sodium erythorbate, sodium metabisulfite, sodium sulfite, sodium thioglycolate, sorbityl furfural, tea tree oil, tetrahexy ldecy I ascorbate, tetrahydrodiferuloy !methane, thiodiglycol, thiodiglycolamide, thiodiglycolic acid, thioglycolic acid, thiolactic acid, thiosalicylic acid, thiotaurine, tocophereth derivatives, tocopherol (vitamin E), tocophersolan, tocopheryl acetate, tocopheryl linoleate, tocopherol linoleate/oleate, tocopheryl nicotinate, tocopheryl succinate, tocoquinone, o-tolyl biguanide, tri(nonylphenyl)phosphate, ubiquinone, vitamin D, zinc dibutyldithiocarbamate, and their derivatives and combinations. (Rodan, US 9,144,434)
Skin Tightening/Toners:
Radiofrequency: WebMD
Toners include agents that create a tightening or tingling are not limited to the following: alumina, aluminum silicate, apricot seed powder, attapulgite, avocado powder, bamboo powder, barley flour, bentonite, calcium carbonate, calcium phosphate, calcium pyrophosphate, calcium sulfate, chalk, chitin, coconut shell powder, colloidal oatmeal, comfrey leaf powder, corn cob meal or powder, corn flour, corn meal, corn starch, diamond powder, diatomaceous earth, dicalcium phosphate, dicalcum phosphate dehydrate, egg shell powder, Fuller’s earth, hydrated silica, hydroxyapatite, kaolin, kiwi seed, lauryl acrylate polymers, loess, magnesium potassium fluorosilicate, magnesium trisilicate, microcrystalline cellulose, montmorillonite, Moroccan lava clay, oat bran, oat flour, oatmeal, oyster shell powder, peach pit powder, peanut flour, pecan shell powder, polyethylene, pumice, raspberry seed, rice bran, rye flour, sand, silica, sodium bicarbonate, sodium hydroxypropyl starch phosphate, sodium magnesium fluoro- 20 silicate, sodium silicoaluminate, soybean flour, sweet almond meal, talc, tin oxide, tricalcium phosphate, walnut shell powder, wheat bran, wheat flour, wheat powder, wheat starch, wood powder, zirconium silicate. (Rodan, US 9,144,434)
Skin Conditioners/Moisteners:
Skin conditioning agents or moisturizers can be classified into different groups such as emollients, humectants, and occlusive agents. Emollients include agents that remain on the upper layers of skin and act as lubricants and improve appearance. Exemplary emollients include but are not limited to the following: lanolin, glycerides, fruit oils, nut oils, vegetable oils, dimethicones, methicone, cyclomethicone, dormin, fatty acids, myristate derivatives like butyl myristate and myristyl myristate, oleate derivates, C1 -C4 glycols, fatty acid glycols, glycol esters, glycerine, glycerols, paraffin, rapeseed oil, long chain alcohols, olive oil, jojoba oil, castor oil, and their derivatives and combinations. Humectants include agents that increase the water content of the top layer of skin. Exemplary humectants include but are not limited to the following: allatoin, agarose, arginine, benzyl hyaluronate, chitosan, copper, corn glycerides, gluconolactone, lactic acid, lactobionic acid, lactose, lysine, kombucha, maltitol, maltose, mannitol, propylene glycol, sodium aspartate, fructose, honey, glycerin, hydroxyethyl urea, and their derivatives and combinations. (Rodan, US 9,144,434)
In addition to skin conditioning agents that provide a moisturizing benefit, there are other skin conditioning agents that improve the appearance of skin. Exemplary skin conditioning agents include but are not limited to the following: cholesterol, cystine, hyaluronic acid, keratin, egg yolk, glycine, gluconolactone, lactic acid, lactobionic acid, panthenol, retinal, salicylic acid, vegetable oil, proteins, vitamins, bisabolol, ceramide, coenzymeA, lecithin and their derivatives and combinations. (Rodan, US 9,144,434)
Skin Bleaching:
Skin bleaching or lightening agents include agents that lighten pigment in skin. The preferred skin bleaching agent is hydroquinone. Brighteners include but are not limited to azelaic acid, bearberry, deoxyarbuten, glycyrrhiza glabra (Licorice) root extract, kojic acid, peat extract, and their derivatives and combinations.(Rodan, US 9,144,434)
Plants and Cosmetics:
The trend of natural cosmetics production has ushered in an era of plant cell culture technology with mroe than 50 cosmetic products based on extracts of plant cell cultures, the bulk of which are made with plant cell suspension cultures. Plant cell culture cosmetic production is not dependent on appropriate seasonal conditions; thus it requries less time and eerngy. Cosmetic extracts dervied from plant cell cutlures suit the market’s increasingly stringent safety requirements. In addition to being free of pathogens, pollutants and pesticide residues, plant cells generated under aseptic laboratory conditions rarely include any malignant cmopound or potential allergen which would otherwise destroy the majority of the plant extrats obtained. Plant cell suspension cultures are cultivated in single-use wave-mixed bioreactors or renwable stainless stell stired bioreactors in commerical production. (Hasnain, “Plants in vitro propagation with its applicaitons in food, pharmaceuticals and cosmetic industries; current scenario and future approaches” Frontiers in Plant Science 2022)
Applicaitons of palnts/flower extracts in cosmetics are significant which include skin oisturing, whitening or tanning products, sunscreens, radical-scavenging antioxidcants, immune stimulants and skin thickeners. (Hasnain, “Plants in vitro propagation with its applicaitons in food, pharmaceuticals and cosmetic industries; current scenario and future approaches” Frontiers in Plant Science 2022)
Raspberry (Rubus ideaus): has been shown to exhibit extraordianry capacity to hydrate skin when tested on human skin in vivo, indcating taht it has tremendous portential as a skin care agent, particularly for dry and ageing skin. (Hasnain, “Plants in vitro propagation with its applicaitons in food, pharmaceuticals and cosmetic industries; current scenario and future approaches” Frontiers in Plant Science 2022)