Gene silencing in a human organotypic skin model.

Here we present a simple and highly reproducible method which allows the study of the effects of a single gene knockdown in an organotypic skin model. Human keratinocytes (KC) were transfected with backbone-modified short interfering RNAs (siRNAs) specific for vascular endothelial growth factor (VEGF) and matriptase-1. Twenty-four hours later the transfected cells were seeded onto fibroblast collagen suspensions and allowed to build up a multilayered epidermis by culture at the air/medium interface for 7 days. Protein expression of both targeted genes remained down-regulated by more than 80% up to 8 days after transfection. As expected, VEGF knockdown by siRNA did not alter epidermis formation in our organotypic skin model. By contrast ablation of matriptase-1 led to aberrant KC differentiation and impaired filaggrin processing and resulted in an epidermal phenotype closely resembling that of matriptase-1 deficient mouse skin. Our results suggest that siRNA-mediated gene silencing is highly efficient in an organotypic skin model and readily allows the assessment of the roles of individual genes during terminal KC differentiation.