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Increasing Interest in Anti-Aging Skincare Growth Factors: EGF & FGF

Skin Anatomy


Our exploration begins with the epidermis, the outermost layer of the skin, functioning as a robust protective barrier. Composed predominantly of keratinocytes and an array of specialized cells, the epidermis can be dissected into five primary sublayers.

Starting with the outermost sublayer, we encounter the stratum corneum, comprised mainly of flattened, lifeless keratinocytes. These cells represent the culmination of terminal differentiation, continuously shedding and regenerating. It's worth noting that terminal differentiation signifies the loss of these cells' ability to divide and proliferate further. Within the context of the skin, keratinocytes, the predominant cell type in the epidermis, undergo this process as they mature from basal keratinocytes in the innermost sublayer to the flattened keratinocytes in the stratum corneum, our current focus.

These deceased keratinocytes in the stratum corneum collaborate to form a resilient barrier, fortified by a lipid matrix that fills the intercellular spaces. This lipid matrix, consisting of ceramides, cholesterol, and free fatty acids, creates an impermeable seal, effectively preventing skin dehydration.

Now, let's venture deeper into the epidermis to explore the next sublayer: the stratum lucidum. This particular layer is primarily found in thick-skinned areas like the soles of the feet and the palms of the hands. It is composed of closely packed, flattened keratinocytes, further enhancing the skin's protective properties.

Continuing our journey inward, we arrive at the stratum granulosum, home to keratinocytes in varying stages of maturation. These cells play a crucial role in producing keratin, a fibrous protein essential for the skin's strength and structure. As keratinocytes progress from this sublayer outward, they undergo a process called "cornification," during which they lose their nuclei and other organelles, gradually becoming flattened and predominantly filled with keratin. By the time these cells reach the stratum corneum, they are essentially lifeless, flat cells densely packed with keratin. It's important to note that, much like keratinocytes, these cells also produce lipids and enzymes (until their organelles are purged), which contribute to the lipid matrix we discussed earlier.

In essence, the lipids produced by the keratinocytes move outward in sync with the keratinocytes themselves. These young keratinocyte cells mature as they journey through these layers, gradually losing their organelles and, consequently, their ability to produce lipids and keratin. By the time they reach the stratum corneum, they are as we discussed earlier—dead keratinocyte cells.

Considering this, as we delve deeper into the next sublayer of the epidermis, it is reasonable to anticipate heightened keratin production, given that these keratinocytes are younger as we move deeper within the skin.

This brings us to the stratum spinosum, characterized by several layers of keratinocytes. Amid these keratinocytes, we find Langerhans cells, the skin's initial line of immune defense. These remarkable cells capture and process foreign agents like pathogens, functioning as antigen-presenting cells (APCs). Their primary role entails capturing antigens, such as pathogens or damaged cells that enter the skin, processing them, and subsequently migrating to the local lymph nodes.

Now, let's journey even deeper into the epidermis, where we encounter the innermost sublayer: the stratum basale. This layer plays host to proliferative basal keratinocytes that undergo division, giving rise to the keratinocytes that ascend towards the epidermal surface. Scattered among them are melanocytes, responsible for producing melanin, which plays a pivotal role in determining skin color and aiding in photoprotection. Additionally, the innermost sublayer boasts Merkel cells, sensory cells associated with nerve endings, contributing to the perception of light touch.

To recap, beginning with the innermost stratum basale, this layer teems with basal cells that divide to produce keratinocytes. As these keratinocytes migrate outward, they mature and accumulate keratin. When they reach a certain stage of maturation, they also contribute to the production of lipids, although these lipids are secreted from the keratinocytes themselves to form the extracellular lipid matrix in the outermost stratum corneum. By the time keratinocytes reach this outermost layer, they have lost their ability to produce keratin due to the absence of organelles, ultimately becoming dead cells filled with keratin—a vital component for skin structure and support.


With this comprehensive understanding of the epidermis, we are now well-prepared to touch briefly on the dermis before delving into the capabilities of cosmetic peptides and growth factors.

The dermis, situated beneath the epidermis, harbors an array of essential components, including blood vessels, nerves, hair follicles, and glands. It can be divided into two distinct sub-layers: the papillary dermis and the reticular dermis.

The papillary dermis, located closest to the epidermis, primarily consists of thin collagen and elastin fibers. Collagen, the skin's most abundant protein, imparts strength and structure, while elastin allows the skin to regain its original shape after stretching or compression. Additionally, the papillary dermis houses an intricate network of lymphatic and blood vessels, as well as phagocytes. These vessels nourish the epidermis and help regulate body temperature, while the lymphatic vessels play a vital role in facilitating the migration of Langerhans cells from the epidermis.

Beneath the papillary dermis lies the reticular dermis, characterized by denser and thicker collagen and elastin fibers. Here, fibroblasts, responsible for producing these essential structural proteins, play a pivotal role. Within this layer, we also find sebaceous glands that produce sebum, a natural oil moisturizing both skin and hair, sweat glands regulating body temperature and excreting waste products, hair follicles, and mast cells.

Throughout our discussion, it becomes evident that the preservation and well-being of keratin, keratinocyte-derived lipids, collagen, and elastin are central to maintaining youthful skin and combating skin aging. Hydration, skin cell turnover rate, and antioxidant defenses also play significant roles in promoting healthy skin.

Growth Factors in Skincare: EGF & FGF

With this foundation established, we are now in a position to embark on a comprehensive exploration of various cosmetic peptides and growth factors. Let's begin by examining EGF, or epidermal growth factor, and its remarkable effects on skin biology.

EGF plays a pivotal role in skin biology by orchestrating the proliferation and regeneration of skin cells, particularly keratinocytes in the epidermis. To comprehend this process, let's explore the intricacies of EGF's interactions.

In essence, EGF molecules bind specifically to EGF receptors (EGFRs), primarily located on the surface of keratinocyte cells within the epidermis. This binding event initiates a cascade of intracellular signaling pathways, culminating in the transmission of signals from the cell surface to the nucleus. These signals trigger profound changes in gene expression and cellular behavior.

The consequences of EGF-induced signaling are noteworthy. Foremost

among them is the stimulation of rapid keratinocyte division, resulting in an increased population of these vital skin cells. This, in turn, contributes to the rejuvenation and thickening of the epidermal layer and enhances keratin production.

While EGF primarily targets keratinocytes in the epidermis, its impact extends indirectly to collagen and elastin production in the dermal layer. This occurs because EGF prompts keratinocytes to differentiate and release signaling molecules and growth factors. Some of these signaling molecules, such as transforming growth factor-beta (TGF-β) and insulin-like growth factor (IGF), can, in turn, stimulate fibroblasts within the dermis.

Activated fibroblasts respond by increasing the production of collagen and elastin, essential structural proteins that provide skin with firmness and elasticity. This is why EGF has gained popularity as a skincare ingredient in the realm of anti-aging. Its ability to stimulate the renewal of keratinocytes, which in turn affects keratin, collagen, and elastin, positions it as an effective solution for targeting fine lines and wrinkles. You'll find EGF featured in various skincare products, including eye creams, sheet masks, serums, and more.

As a bonus, I am currently working on a homemade EGF skincare formulation. Once I refine it to my satisfaction, I'll be delighted to share the process with you.

Now, before we dive deeper into the world of cosmetic peptides and explore additional growth factors, let's briefly discuss another crucial growth factor: FGF, or fibroblast growth factor.

Much like EGF, FGF molecules bind to specific receptors, known as FGF receptors (FGFRs), located on fibroblast cells within the dermis. This binding event initiates a complex series of biochemical signals within the cell, ultimately leading to cell proliferation. As we know, fibroblasts are responsible for producing collagen and elastin, making FGF a key player in enhancing skin firmness and elasticity.

These two growth factors have gained prominence in the skincare world, but it's essential to note that their inclusion in formulations can be cost-intensive. In upcoming segments, I'll share valuable tips and tricks for formulating skincare products, allowing you to harness the benefits of these potent ingredients effectively. Furthermore, we'll delve into lesser-known growth factors and explore a plethora of cosmetic topical peptides. For now, stay tuned for part two, where we'll continue our captivating journey into the world of skincare science.


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