Observations: Although keratinocyte gene therapy is not yet being tested in clinical trials, animal models do exist where keratinocytes are being used to secrete factors such as human growth hormone and factor IX (for hemophilia) into the systemic circulation. Genetic diseases of the skin such as recessive epidermolysis bullosa dystrophica or xeroderma pigmentosum have not yet been treated with keratinocyte gene therapy in animal models.

Conclusions: Keratinocytes have many advantages as a target cell in gene therapy, and progress has been made using animal models. However, the sustained and efficient delivery of factors to the bloodstream by keratinocytes expressing a transgene has not yet been accomplished. Future goals are to obtain adequate levels of the desired factors, hormones, or enzymes for sustained periods of time, either in keratinocytes or in the vascular system.