Skin Lightening The Model MatTek's MelanoDerm™ System consists of normal, human-derived epidermal keratinocytes (NHEK) and melanocytes (NHM) which have been cultured to form a multilayered, highly differentiated model of the human epidermis. The NHM within co-cultures undergo spontaneous melanogenesis leading to tissues of varying levels of pigmentation. The tissues are prod..