Skin is composed of two main layers that can be treated through topical application of skincare products,
the outermost epidermis and the deeper dermis. The epidermis is the barrier between our bodies and the outside word. It is predominantly made up of keratinocyte cells. Keratinocytes are arranged in layers through the epidermis. As these cells divide and proliferate, they begin to differentiate. This process is called keratinization, and it involves the production of specialized structure proteins (like keratin), secretion of lipids and the formation of a cellular envelope of cross-linked proteins.
The dermis provides strength and elasticity, and includes the vascular, lymphatic and neuronal systems. It is relatively acellular and is primarily made up of complex extracellular matrix proteins. It is particularly rich in collagen fibers, which make up about 75% of the dermis’ dry weight. Fibroblasts are the main cellular component of the dermis, and it is heavily involved in the synthesis of many of the extracellular matrix components. Blood vessels that supply nutrients to both skin layers are also present in the dermis.
Melanocytes are cells that possess the unique ability to synthesize melanins within melanosomes. Melanin is one type of pigment that determines human skin color. There is also hemoglobin (red), ferritin and hemosiderin (brown), carotene (yellow), and bilin (yellow). Among those, melanins are thought to play key roles in determining human skin pigmentation. Iron proteins, such as hemoglobin, ferritin, and hemosiderin are equally important in contributing to skin tone but are potentially major contributors to skin aging and photo-aging. Because iron is extremely effective in producing oxidants through Fenton/Haber-Weiss reactions, accumulation of these iron proteins in the skin increases the risk of releasing iron and causing oxidative damage to the skin.
With decades of research and experience behind us, we have developed different cell culture models.
A single homogenous cell system to assess the activities of ingredients and finished products in various mediums, including immortalized human keratinocyte HACAT cells, normal human epidermal keratinocytes, primary human dermal fibroblasts and melanocytes;
A co-cultured system (e.g., keratinocytes and dermal fibroblasts) to investigate the effects of actives on keratinocytes (the top layer of skin) by releasing different mediators and growth factors and the effects of those biomolecules on dermal fibroblasts (the lower layer of skin);
3D skin culture system to mimic human skin structures for permeation of actives into the skin;
Primary human skin cells at older ages to determine if the actives reverse signs of aging by comparing with cells at younger age;
Pre- and post-menopausal cell cultures to investigate how actives affect aging under menopausal conditions as menopause has significant associations with skin aging