Development of CPP-Based Methods for Delivery of miRNAs into the Skin and Airways: Lessons from Cell Culture and Mouse Models

microRNAs (miRNAs) have capacity to modulate numerous biological processes and therefore synthetic oligonucleotides mimicking or inhibiting particular miRNA have potential in the development of novel types of therapeutics. We have elaborated several methods for safe and efficient overexpression of miRNAs using self-forming nanocomplexes of PepFect or NickFect type of cell-penetrating peptides (CPPs) and oligonucleotides mimicking well-characterized anti-inflammatory miR-146a. We focus on chronic inflammatory diseases affecting epithelium, such as atopic dermatitis and asthma harnessing respective cell cultures and mouse models. Here we provide protocols for miRNA transfection into primary human keratinocytes, primary human bronchial epithelial cells, and human monocyte-derived dendritic cells using CPPs PepFect14, NickFect70, NickFect71, and NickFect72. In addition, we provide protocols for application of CPP-miRNA nanocomplexes in in vivo mouse models of irritant contact dermatitis and allergic airway inflammation.