Your skin is your strongest form of protection from a plethora of environmental insults. From bad weather, to pathogens, to UV exposure, to injury, skin is the barrier that not only keeps your tissues and organs in place, but also keeps your body safe from contamination and infection.

Multiple cell types comprise the different layers of the skin. Keratinocytes are the most common cell type and make up over 95% of skin cells. Keratinocytes originate in the epidermis in a layer called the stratum basale (see figure below). Here they divide and proliferate to produce daughter cells that migrate into the upper layers of the epidermis and eventually to the skin surface (a layer called the stratum corneum).

Keratinocytes differentiate as they travel through the outer layers of the epidermis to the surface of the skin. During this process, they form organized structures and secrete proteins (keratin) and lipids that become part of the extracellular matrix and form a strong physical barrier within the skin. This protective barrier shields the body from invading pathogens and damaging environmental factors. In response to infection, keratinocytes can secrete inflammatory factors that activate the immune system to destroy such pathogens. They also play an important role in wound healing by migrating to sites of injury in skin to fill open wounds.

You can’t talk about skin and keratinocytes without mentioning cancer. Skin cancer comes in many forms and can originate in different layers of the skin and in different skin cell types. Melanoma is a form of skin cancer that affects melanocytes in the outer layer of the skin. Cancers that directly target keratinocytes include basal cell carcinomas and squamous cell carcinomas.

Models Using Keratinocytes

Since keratinocytes are the predominant cell type in human skin, it only makes sense that they would be ideal cell models for studying fundamental processes of human development and disease. The possibilities of what you can research using keratinocytes are endless, but here are a few examples:

Epithelial biology
Would healing
Toxicology
Skin disease (psoriasis, eczema)
Skin cancer
Response to UV radiation exposure

Lifeline® Normal Human Epidermal Keratinocytes

Lifeline® offers normal human epidermal keratinocytes from adult and neonatal tissue. These cells are cryopreserved as primary cells and are guaranteed to perform optimally for at least 15 population doublings when cultured in Lifeline® specialized serum-free DermaLife K medium. Our serum free conditions allow for maximal keratinocyte proliferation rates while delaying terminal differentiation.

For your convenience, Lifeline® also provides a 10-donor pool of normal human keratinocytes. This option offers a range of keratinocyte cell lots that cover a diverse array of donor demographics to avoid issues of donor variability in research at an economical price.

Keratinocytes in Action

Lifeline® keratinocyte products are one of the main go-to sources for scientific experiments on human keratinocytes and skin. There are over 30 publications that reference our keratinocyte cells and cell culture media. Here is a look at a few of these studies to see how our keratinocyte products perform in the field.

Studying Pathogenic Bacteria Skin Colonization

Breij et al. explored how pathogenic bacteria colonize human skin, an event that can lead to host invasion and patient infection. They specifically studied how multidrug-resistant strains of Acinetobacter baumannii colonized a 3D epidermal skin model, which was generated from human keratinocytes that were cultured in Lifeline® DermaLife K medium. They found that some strains of Acinetobacter developed into biofilms on their 3D skin model, but did not alter keratinocyte function or proliferation. They also determined that the disinfectant chlorhexidine was capable of killing off the pathogenic bacteria without causing harm to the cells. Ultimately this study offers a suitable in vitro 3D skin cell model to study bacterial pathogenesis and test potential antimicrobial strategies.

Understanding how Melanocytes and Keratinocytes Respond to UV Radiation and Arsenic

Cooper et al. looked at the mechanisms by which UV radiation (UVR) and arsenic exposure can cause melanoma (skin cancer). Previous work has shown that UVR and arsenic work together to promote various forms of skin cancer through mechanisms including elevating oxidative stress and inhibiting DNA repair in cells. This study compared the response of melanocytes and keratinocytes to UVR and arsenic exposure. Normal human neonatal epidermal keratinocytes and normal human neonatal epidermal melanocytes along with DermaLife culture medium purchased from Lifeline® were used to conduct these experiments. The authors found that keratinocytes were more sensitive to UVR-mediated DNA damage but that both cell types were equally sensitive to arsenic inhibition of DNA repair. They concluded that chronic arsenic exposure can act as a co-carcinogen with UVR to promote melanoma.