HaCaT

HaCaT is an immortalized human keratinocyte cell line derived from adult human skin, commonly used as an in vitro model of the epidermis. The name HaCaT derives from “human adult keratinocytes.” The cell line was established in 1988 by Boukamp and colleagues, originating from adult skin and spontaneously immortalized in culture.

HaCaT cells maintain many characteristics of normal keratinocytes, including expression of basal keratins K5 and K14, and the ability to undergo calcium-dependent differentiation to express suprabasal markers such as K1, K10, involucrin, and loricrin. Calcium concentration in the culture medium regulates differentiation; increasing extracellular Ca2+ promotes stratification and differentiation. In standard culture, HaCaT cells are grown in DMEM with 10% fetal bovine serum, at 37°C in a 5% CO2 atmosphere.

Genetically, HaCaT cells carry mutations in the TP53 gene, leading to altered p53 function, and they are aneuploid. These changes contribute to spontaneous immortalization but do not render the cells tumorigenic; HaCaT cells are generally non-tumorigenic in nude mice.

Applications of HaCaT include studies of epidermal differentiation, keratinocyte signaling, wound healing, genotoxicity, and responses to ultraviolet radiation, as well as the development of organotypic skin models that mimic barrier formation. They are widely used in toxicology and cosmetics research as a surrogate for human epidermis.

Limitations include the p53-related and other genetic alterations that mean HaCaT cells do not fully recapitulate normal primary keratinocytes or in vivo epidermis. Results are typically validated with primary cells or complementary in vivo models when possible.