Human skin is the largest body organ and undergoing many changes. Therefore, proper skin care is impossible without knowledge of its physiology and function. The skin protects us from harmful substances present in the environment, blocking access to the interior of the body microorganisms.
It is also the main enclosure to prevent escape of water from the body.
Thermoregulatory functions. Under the influence of sunlight on the skin followed by the production of vitamin D, necessary, inter alia, for proper bone growth.
In the structure of the skin can be divided into three main layers. Deepest subcutaneous tissue, connective tissue composed of the right. The next layer is the dermis, most often represented by the fibroblasts responsible for supporting protein synthesis, such as collagen and elastin. These two proteins build an extracellular matrix or network elasticity and holding the skin. The outer part of the skin is the epidermis.
Aging is inevitable and the body’s natural process consisting, inter alia, the reduction of the biological activity of the body, slowing down the processes of regeneration and reducing resistance and response to environmental stress. The skin, due to direct exposure to harmful external environmental factors, aging is usually faster than the other organs of the human body, and the signs of aging are more visible. The aging process of the skin is the result of two mechanisms: intra- and extrinsic. This first type of aging, genetic or otherwise called chronological, it is a natural process dependent on the biological clock. In contrast, extrinsic aging (photoaging, aging caused by sun) is a process caused by external factors, especially sunlight.
Physiological process of aging is not fully understood. In the course of importance to both genetic factors, hormonal and environmental factors. Chronological aging begins, initially in an invisible manner, at the age of 25 – 30 years. It is genetically determined, and the mechanism has an individual character and conduct. Each cell of the skin is consistently implementing the program laid out in life – including a coded term life. Is reduced expression of genes responsible for cell proliferation, and have a higher activity of tumor suppressor genes. Therefore, growth processes are inhibited and the destructive processes begin to dominate.
Well documented phenomenon often observed to lower the ability of cells to respond properly to different growth stimuli and metabolic inefficiency. With age, the skin cells lose their ability to synthesize supporting fibers of the skin and reduces the speed of the course of various metabolic processes.
The activity of the cells decreases the enzyme responsible for replication of the telomeres which are shortened with each cell division. Telomere shortening can therefore be considered an “internal calendar” countdown living cells. Protein synthesis is impaired, those responsible for communication, as well as those associated with energy production and the mechanisms to repair damage (thus reduced ability to repair DNA, among others). Changes to the composition of cell membranes, which makes it difficult transmembrane transport of substances, and consequently leads to the accumulation of toxic substances in the cell. Decreases with age and number of mitochondrial activity, which leads to a reduction in ATP levels and impairment of the ability of regenerative cells.
The advent of hormonal disorders and a decrease in circulating levels of sex hormones in women over 35 year of life is one of the elements extrinsic aging. In women, declining estrogen levels leads to the appearance of wrinkles and skin elasticity deterioration due to the changes observed within the supporting fibers.
Aging of the skin is an inevitable process, continuously progressive and affects all layers of the skin, wherein the intrinsic aging have less impact than the extrinsic.
We can observe the clinical characteristics extrinsic aging:
• dryness and roughness, and sometimes itchy skin,
• numerous small wrinkles,
• atrophy of the skin not exposed to sunlight,
• severe hyperkeratosis of the skin due to decreased secretion of the sebaceous glands and sweat glands,
• paleness of the skin by reducing the number and reactivity of the capillaries,
• discoloration, age spots.
Skin aging is caused by the action of extrinsic factors (environmental). Effect of damaging environmental factors expressed mainly premature aging of the skin, most prominent in the areas exposed to UV radiation chronic – on the face and hands. It is estimated that in the unprotected skin, 80% of the changes observed during the aging process is induced by ultraviolet radiation.
Changes characteristic of extrinsic aging of the skin are caused by direct exposure to UVA and UVB rays, and their indirect action associated with induction of an inflammatory response in the skin cells. UVA rays do not cause reddening of the skin, but play a role in the development of solar tissue degeneration, damage collagen, favor the formation of skin cancer and skin diseases. They can also, as infrared rays to cause damage to the capillaries and blood circulation disorders of the skin. UVB rays are responsible for the solar erythema and burns the skin and play a decisive role in the formation of precancerous and cancer of the skin (they have mutagenic effects). About 10% of UVB rays penetrate the dermis damaging the fiber support. UVB rays stimulate the secretion of epidermal interleukin 1 (IL-1), an intermediate in the formation of the inflammatory response. In the dermis, there is a greater increase in the synthesis and activity of the collagen fiber-degrading metalloproteinases, which leads to a reduction in density and loss of the supporting tissue of the skin.
In addition to UV rays, a very large impact on the processes of aging are, released in the atmosphere and produced within the body, free radicals. These particles generally run as a very aggressive oxidizers destroy skin structure. With age, decreasing the efficiency of the body’s own antioxidant systems, and, consequently, the skin loses the ability to repair damage.
Both direct UV and not generated by the free radicals damage components of the epidermal barrier. Degradation of components of the stratum corneum intercellular cement (unsaturated lipids) and decrease the activity of sebaceous glands. In the case of dry cerium it deteriorates the water balance of the skin.
Extrinsic factors cause changes in the epidermis and dermis.
The main symptoms of extrinsic aging are:
• dryness and roughness of the skin,
• pigmented lesions,
• small lumps and bumps on the skin (solar elastosis)
• sebaceous gland hypertrophy,
• cancers of the skin.
The active type of anti-aging
The aging of our body, including the skin, is inevitable. Through healthy lifestyle and, more importantly, proper care, however, can have an impact on how and how fast aging will run. The search for molecules and solutions that render despite elapsing years, our skin would look young and working smoothly, remains a challenge for physicians, biologists, and cosmetologists. Our modern cosmetology offers products anti-aging type containing different types of active substances. Proteins with a tissue growth factors are a new trend in anti-aging care. These membrane receptor proteins involved in the stimulation of DNA synthesis and proliferation of many cell types such as fibroblasts, epithelial cells, smooth muscle cells, myoblasts, chondrocytes, or glial cells. It was also shown that the cell growth factors to stimulate directed migration of chemotaxis of cells or epithelial cells and fibroblasts. They play an important role in many stages of development and morphogenesis of cells, as well as angiogenesis or wound healing. However, over time the level of expression of cell growth factors decreases, resulting in slow pace of recovery, or malfunctioning defense system of the skin cells. Therefore, the cosmetic industry is interested in using tissue growth factor as a potential anti-wrinkle preparations or anti-aging. The market is just a few materials designed to mimic tissue growth factors or affect specific metabolic pathways in the skin. These are primarily short peptide sequences act as signaling factors.
Peptides – composed of several (at least two) amino acid residues. Peptides for use in cosmetology are created based on the sequences of molecules occurring naturally in the body, e.g. the skin of the structural proteins, growth factors, receptors, signaling molecules, cytokines.
Peptides can be divided into:
• signal peptides – stimulate the synthesis of matrix components, collagen, elastin, proteoglycans, glycosaminoglycans, fibronectin
• peptides inhibit the activity of enzymes such as metalloproteinases, tyrosinase
• inhibitory peptide neurotransmitters – such as acetylcholine, norepinephrine, catecholamines
• Peptides-media – such as copper media
The aging of the skin, in particular, exposure to UV radiation, leading to changes in the skin characterized by defects in the extracellular matrix (ECM). It is a gel network of proteins and sugars, scaffolding functions acting in all three layers of the skin: the dermis, the dermoepidermal junction and in the epidermis. The extracellular matrix is ??mainly composed of water, collagen, elastin, glycoproteins and carbohydrates. 70% of the proteins in the skin consists of collagen. It has a very high tensile strength and is the main component of tendons. It is also responsible for skin elasticity. The loss of collagen from the skin causes wrinkles in the process of aging.
TGF protein (called Transforming Growth Factor), belonging to the group of growth factors composed of three smaller subunits TGF-1, TGF-2 and TGF-3. TGF-is responsible for processes such as angiogenesis, embryogenesis, wound healing or anti-inflammatory activity and the synthesis of collagen. This protein is synthesized in all cell types. It occurs in an inactive form and must be raised in order to be recognized by cellular receptors and activate a biological response. The mechanisms controlling the conversion of the inactive to the active form are key regulators of TGF-.
One of the mechanisms regulating the activity of TGF-? is its interaction with the extracellular glycoprotein – thrombospondin 1 It is involved in the transmission of information between cells and the extracellular matrix and cells by binding to fibrinogen, fibronectin, laminin, collagen or integrin. Also connects to the TGF-? site specific amino acid sequence, thereby activating it. Knowing this sequence, it was possible to create a short peptide sequences mimicking the sequences of thrombospondin 1, so as to activate the TGF-and, thus, the synthesis of collagen.
The use of technology that mimics the natural mechanism to produce collagen via activation of TGF-up for the shortage of this component and causes the skin to look younger.
Atomic Force Microscopy (AFM)
One of the most modern techniques used to confirm the effectiveness of cosmetic products is the Atomic Force Microscopy (AFM Atomic Force Microscopy). AFM is a member of the class of scanning microscopes, scanning the sample surface with the probe. This probe is a blade fitted to the flat a spring (called mikrobelce). The tip moving across the surface of the sample, causes the position of the springs and the odkszatlcenia. Any deflection of the springs is recorded by an optical system, and the result of this measurement is converted into a voltage signal. An image of the surface topography of the sample is obtained by mapping a transmitter elongation values at each point on the sample probe position. Additionally, each is recorded, even a small deflection of the springs, which allows to generate a topographical image of the sample in very high resolution.
A significant advantage of an atomic force microscope, unlike other commercially available measuring equipment, is the ability to perform tests on living systems, including in particular the cells, in an aqueous medium – their natural physiological environment. This allows a more accurate determination of the topography of the tested objects, as well as the dynamics of the cell membrane, and a better understanding of complex physiological processes. Measurements in liquid media also allow for the observation of changes of topographic and mechanical properties of the cell membrane under the influence of soluble pharmacological agents used to change the pH or the concentration of substances in biological material surrounding solution.
Atomic Force Microscopy, in addition to imaging of living cells in their natural, physiological medium, it is extremely useful in the study of mechanical properties such as elasticity, friction, adhesion, or the amount of force.
TGF-Technology AFM studies
The skin cells can also ananlizowac AFM technique in vitro. The experiment was performed in collaboration with the Department of Materials Inazynierii Warsaw University of Technology, on the living cells of the dermis isolated from skin biopsies derived from women aged 20, 30, 40 and 60 years. For each age group tested control cells (cultured in medium alone) and the cells in the presence of TGF activation peptide.
The aim of the study was to evaluate the effect of TGF technology used in the new cosmetics Lirene IDEALE the flexibility of the cells by observing the Atomic Force Microscope and the calculation of the so-called. Young’s modulus. The analysis was based on the collection and evaluation of force curves. Monitored were swinging arm with the blade of a piezoelectric scanner with the sample. This deflection corresponds to the force acting between the end of the blade and the surface of the sample. The elastic properties of the surface characterized by the relationship between intendancia (depth) and engaging a force. Most of the material is deformed in a flexible or malleable. Particularly susceptible to such deformation are living tissues, including cell. In the absence of deforamacji the sample surface, the indentation is zero. In the case of cells is small deflection of the arm with the blade, which is caused by the bending of the flexible surface under the effect of force (indentation formed). The indentation size is calculated by comparing the values obtained for Idel hard materials (e.g., glass culture vessel) with those obtained for the elastic material (living cells).
The results indicate a decrease in the value of Young’s module (ie, increase flexibility) for all dermis cells cultured in the presence of the peptide, with the best responded to the stimulation of a cosmetic ingredient derived cells from persons 40 and 60 years old. The result also showed improvement in the flexibility of these cells to the level of flexibility of the cells isolated from a person 20 – and 30-year-old.
The above example of using Atomic Force Microscopy is the latest example of the use of the described techniques in cosmetology and the only one on the current state of knowledge that deals with the study of elasticity of living cells of the dermis. Research Atomic Force Microscopy method enables accurate and very precise determination of the impact of cosmetic products or individual active ingredients used in the cosmetic industry for healthy skin and hair.