Why do we study “SKIN”?

“Skin is the most sensitive organ response to the external environment.”

Figure1. Skin structure of human

The largest organ in the human body; SKIN

The integument or skin is the largest organ of the body, making up 16% of body weight, with a surface area of 1.6m2. It has several functions, the most important being to form a physical barrier to the environment, allowing and limiting the inward and outward passage of water, electrolytes and various substances while providing protection against micro-organisms, ultraviolet radiation, toxic agents and mechanical insults.

There are three structural layers to the skin: the epidermis, the dermis and subcutis. Hair, nails, sebaceous, sweat and apocrine glands are regarded as derivatives of skin (Figure 1.). The epidermis is the outer layer of the skin, which helps waterproof and protect the skin and underlying tissues from exterior environment. It is constituted at 95% of keratinocytes, but also containing melanocytes, langerhans cells, merkel cells. Keratinocyte is involved in stratum corneum and melanocyte produce melanin which is related to skin color.

Dermis is composed mainly of connective tissues containing collagen and elastic fibers, and which give elasticity, firmness and strength. It also contains mechanoreceptors that provide the sense of touch and heat, hair follicles, sweat glands, sebaceous glands, apocrine glands, lymphatic vessels , blood vessels and natural moisturizing factors such as Na-PCA, hyaluronic acid etc.

The subcutaneous tissue is a layer of fat and connective tissue that houses larger blood vessels and nerves. This layer is important is the regulation of temperature of the skin itself and the body. The size of this layer varies throughout the body and from person to person.

Dynamic organ; SKIN

Skin is a dynamic organ in a constant state of change, as cells of the outer layers are continuously shed and replaced by inner cells moving up to the surface. Although structurally consistent throughout the body, skin varies in thickness according to anatomical site and age of the individual.

The outermost layer of the epidermis is stratum corneum, consisting of dead cells (corneocytes) that lack nuclei and organelles. It is composed of about 12-16 layers of corneocytes, a protein complex that is made of tiny threads of keratin in an organized matrix. Before the mid-1970's the stratum corneum was thought to be biologically inert, like a thin plastic sheet protecting the more active lower layers of the skin. However, in the past 30 years, scientists have discovered that the biological and chemical activity of the stratum corneum is very intricate and complex. When the keratinized stratum corneum peels off from the surface layers, the new cells are produced down below. This process normally takes about 28 days to complete. It is very important to maintain that cycle.

Disorder of the cycle can cause skin trouble and disease. Understanding the structure and function of the dynamics for skin is vital because it is the key to healthy skin and its associated attractive appearance.

Disease related to skin

The skin plays a very important role as a barrier to chemicals and other contaminants entering the body. Skin disease may disrupt this barrier function. Most of disease related to outer layer of skin can be easily treatable, while some of skin diseases are serious and chronic and it does not even known about what is cause. Furthermore, the changes of diet, habit, and environment contamination cause steady increase of skin disease.

There are many diseases that can affect your skin. Some like vitiligo cause the skin to lose its natural color, and some like alopecia areata can make the hair fall out. Another skin disease like epidermolysis bullosa can cause painful blisters. Psoriasis can cause itchy, scaly red patches. The understanding of what it causes skin disease has not been extensively studied. However, there is a lot of issues to be addressed. As technology is developed and knowledge is accumulated, the Cosmeceuticals=Cosmetics+Pharmaceuticals has been spotlighted and getting attention from consumer, which showed efficacy for improving skin problem or disease.

Representative skin diseases are following:

Albinism/ Piebaldism/ Vitiligo / Halo neves / Melasma
Autoimmune disease, atopic dermatitis
Acne, rosacea
Skin cancer

Advantages of studying skin system

- Great studying system ; Skin

Skin is our most accessible tissue, which give you access of all types of cell and easily cultivable. By these means, it is possible to study about skin disease under basic cell level. Furthermore it is not bring up the ethical issues. It shows almost similar physiological and biochemical functions with other cells. These features will allow us to follow the dynamics and behavior of the cells and furthermore, give us ways to studying skin disease and aging in the cell level.

- Benefit for studying skin for commercial purposes

It has not been fully discovered the cause of skin disease or trouble. Candidates for active compounds or new drugs that have functions in skin disease or trouble can be primarily commercialized for cosmetic ingredients. The main purpose of active compounds for cosmetic is alleviation of symptom related to skin trouble or disease, therefore it is easier to commercialize than new drug compounds.