Reconstructed human epidermis composed of keratinocytes, melanocytes and Langerhans cells

In addition to their basic biological interest, models of reconstructed epi dermis provide useful tools for in vitro assessment of the toxicology and e fficacy of new chemicals and drugs. The fact that the majority of these in vitro models are composed only of keratinocytes has excluded their use in t he fields of skin pigmentation and immunology. After the successful introdu ction of functional melanocytes into the epidermal reconstruct, the integra tion of Langerhans cells remains an important challenge, particularly since after isolation of Langerhans cells from human epidermis, these cells cann ot be subcultured and do not integrate into the reconstructing epidermis. T he authors show that cord blood derived and CD34(+) progenitors isolated fr om the peripheral blood give rise to residential Langerhans cells when co-s eeded with normal human keratinocytes.