Netherton syndrome (NS) is a debilitating congenital skin disorder caused by 
mutations in the SPINK5 gene encoding the lymphoepithelial Kazal-type-related 
inhibitor (LEKTI). It is characterized by defective keratinization, recurrent 
infections, and hypernatraemic dehydration with a mortality rate of about 10% in 
the first year of life. Currently, there are no curative treatments for NS. We 
have developed a HIV-1 based, self-inactivating lentiviral vector to express 
SPINK5 in keratinocytes as part of an ex-vivo gene therapy strategy for NS. High 
transduction efficiency was achieved in NS keratinocytes and reconstitution of 
LEKTI expression was confirmed in previously deficient cells. These genetically 
corrected keratinocytes were further tested in an in vitro organotypic culture 
(OTC) system and in vivo mouse/human skin engraftment model. Results showed 
correction of epidermal architecture in both OTCs and regenerated skin grafts. 
Importantly, the results from corrected skin grafts indicated that even where 
detectable LEKTI expression was restored to a limited numbers of cells, a wider 
bystander benefit occurred around these small populations. As LEKTI is a 
secreted protein, the genetically modified graft may provide not only an 
immediate local protective barrier, but also act as a source of secreted LEKTI 
providing a generalized benefit following ex-vivo gene therapy.