157. Breaching the Barrier: Topical Delivery of Peptide-Based Nanocomplexes in Skin

Skin is a dynamic organ known for its protective functions. With a wide range of associated deblitating and untreatable conditions it has been explored for topical delivery of therapeutics for sustainable effects. In spite of the obvious advantages of the organ delivery of various hydrophilic molecules to skin has met with limited success. This could be attributed to the unique lipid composition and compact organization of stratum corneum which impedes the entry of such molecules in skin limiting their potential clinical translations. Recent approaches involve use of minimal invasive methods for macromolecules delivery to skin. However, issues with efficiency, toxicity, robustness and high costs limit their universal use. Thus one of the key challenges in skin biology is to develop noninvasive, non-toxic and efficient methods for delivery of biomolecules to and through the skin. We have developed a peptide-based delivery system for efficient nucleic acid delivery in skin upon topical application as nanocomplexes. Further we have tried to improvise the delivery efficiency using safe enhancers and modified the carrier to attain specific targeting in skin. The peptide is secondary amphipathic in nature that tends to acquire alpha-helical structure in hydrophobic environment and retains in skin till 24hrs as seen through Franz assay. We have also found that upon topical application of peptide either in bare form or as nanocomplex to skin cells or human foreskin tissue it exhibits efficient cellular entry, high transfection efficiency as well as skin penetration ability as assessed by fluorescence and luciferase based assays. Transfection efficiency observed was equivalent to that obtained with commercial agents. In-vivo studies using SKH-1 hairless mice model showed similar activity. To realize the clinical potential of the work we have shown delivery of therapeutically relevant nucleic acids in skin with effective and traceable amounts of therapeutic molecules. The cytotoxicity and dye penetration test analysis of bare peptide and nanocomplex revealed no deleterious effect on skin cells as well as tissue. Mechanistic insights revealed that the entry of the peptide in skin is mediated partially by fluidization of lipids in addition to transient disruption of junctional proteins as seen through FTIR and time lapse studies. To further enhance the transfection efficiency of these nanocomplexes in skin without compromising its integrity, pre-application of silicone oil worked as an effective strategy. We further modified the peptide with a keratinocyte specific ligand and observed high transfection efficiency in selective cellular population. Presently we are validating the same in skin tissue. Overall we describe development of a convenient, clinically effective and possibly patient compliant approach to facilitate delivery of macromolecular therapeutics in skin.