Transcriptional targeting of adenoviral gene delivery info migrating woundkeratinocytes using FiRE, a growth factor-inducible regulatory element

Impaired cutaneous wound healing is a common complication in diabetes, isch emia and Venous insufficiency of lower extremities, and in long-term treatm ent with corticosteroids or other immunosuppressive agents. In development of gene therapy for wound repair, expression of therapeutic transgenes shou ld be precisely targeted and controlled. Here, we describe a recombinant ad enovirus RAdFiRE-EGFP, in which a growth factor inducible element (FiRE) of the murine syndecan-1 gene controls the expression of enhanced green fluor escent protein (EGFP) reporter gene. Treatment of RAdFiRE-EGFP-transduced m urine epidermal keratinocytes in culture with FiRE-activating growth factor markedly enhanced the expression of EGFP. In ex vivo organ culture of woun ded murine skin transduced with RAdFiRE-EGFP, the EGFP expression was speci fically detected in wound margin keratinocytes, but not in intact skin. Act ivity of EGFP was first detected 2 days after a single application of RAdFi RE-EGFP and persisted up to 10 days. Similarly, FiRE-driven EGFP expression was detected specifically in epidermal keratinocytes in the edge of incisi onal wounds in murine skin transduced with RAdFiRE-EGFP. In contrast, adeno virus-mediated lacZ expression driven by CMV promoter was detected scattere d in epidermal, dermal and subcutaneous layers in ex vivo and in vivo wound s, as well as in intact skin. These data demonstrate the feasibility of FiR E as a tool for transcriptional targeting of adenovirus-mediated transgene expression to cutaneous wound edge keratinocytes.