Gene silencing following siRNA delivery to skin via coated steel microneedles: In vitro and in vivo proof-of-concept

Abstract

The development of siRNA-based gene silencing therapies has significant potential for effectively treating debilitating genetic, hyper-proliferative or malignant skin conditions caused by aberrant gene expression. To be efficacious and widely accepted by physicians and patients, therapeutic siRNAs must access the viable skin layers in a stable and functional form, preferably without painful administration. In this study we explore the use of minimally-invasive steel microneedle devices to effectively deliver siRNA into skin. A simple, yet precise microneedle coating method permitted reproducible loading of siRNA onto individual microneedles. Following recovery from the microneedle surface, lamin A/C siRNA retained full activity, as demonstrated by significant reduction in lamin A/C mRNA levels and reduced lamin A/C protein in HaCaT keratinocyte cells. However, lamin A/C siRNA pre-complexed with a commercial lipid-based transfection reagent (siRNA lipoplex) was less functional following microneedle coating. As Accell-modified “self-delivery” siRNA targeted against CD44 also retained functionality after microneedle coating, this form of siRNA was used in subsequent in vivo studies, where gene silencing was determined in a transgenic reporter mouse skin model. Self-delivery siRNA targeting the reporter (luciferase/GFP) gene was coated onto microneedles and delivered to mouse footpad. Quantification of reporter mRNA and intravital imaging of reporter expression in the outer skin layers confirmed functional in vivo gene silencing following microneedle delivery of siRNA. The use of coated metal microneedles represents a new, simple, minimally-invasive, patient-friendly and potentially self-administrable method for the delivery of therapeutic nucleic acids to the skin.

Going beyond the liver: Progress and challenges of targeted delivery of siRNA therapeutics

“…The most promising possibility for large hydrophilic agents to overcome this barrier is physical disruption by the use of microneedles. Therapeutic siRNAs can be coated onto those stainless steel needles, or injected with microneedle devices [76,77]. Reports show a good epidermal uptake and gene silencing effect, but little to no absorption into dermal capillaries and systemic circulation.…”

Transdermal delivery of drugs with microneedles: Strategies and outcomes

“…The siRNA targeting the reporter (luciferase/GFP) gene was coated onto microneedles and delivered to mouse footpad. Quantification of reporter mRNA and intravital imaging of reporter expression in the outer skin layers confirmed functional in vivo gene silencing following microneedle delivery of siRNA [58].…”

A Review about various Nanomaterials in Drug Delivery Systems and their Applications

“…The siRNA aiming the corresponding (luciferase/GFP) gene was coated against microneedles and conveyed to mouse footpad. Quantification of corresponding mRNA and intravital imaging of corresponding expression in the external dermal linings established efficient invivo gene silencing after delivery of siRNA via microneedles [66].…”