Delivery of siRNA and other macromolecules into skin and cells using a peptide enhancer

Delivery of macromolecules into cells and tissues such as skin is a major challenge. This obstacle poses a particular challenge for the delivery of siRNA where cellular and tissue level transport barriers need to be overcome. siRNAs are potential therapeutics for various dermatological diseases including psoriasis, atopic dermatitis, and cancer; however, their utility is limited by their low absorption across the stratum corneum (SC) and into viable cells of skin. Here, we address this challenge using a peptide identified by phage display termed skin penetrating and cell entering (SPACE) peptide. In vitro studies indicated that the SPACE peptide, when conjugated to cargoes such as small molecules and proteins, was able to facilitate their penetration across the SC into epidermis and dermis. The peptide also exhibited increased penetration into various cells including keratinocytes, fibroblasts, and endothelial cells, likely through a macropinocytosis pathway. The ability of SPACE peptide to deliver siRNA was tested in vivo using two targets, interleukin-10 and GAPDH. Conjugation of the peptide to siRNA led to their enhanced absorption into skin and knockdown of corresponding protein targets.