Implementing Efficient Peptoid‐Mediated Delivery of RNA‐Based Therapeutics to the Vocal Folds

Abstract

ObjectiveWe hypothesize that Smad3 is a master regulator of fibrosis in the vocal folds (VFs) and RNA‐based therapeutics targeting Smad3 hold therapeutic promise. Delivery remains challenging. We previously described a novel synthetic peptoid oligomer, lipitoid L0, complexed with siRNA to improve stability and cellular uptake. An advantage of these peptoids, however, is tremendous structural and chemical malleability to optimize transfection efficiency. Modifications of L0 were assayed to optimize siRNA‐mediated alteration of gene expression.MethodsIn vitro, Smad3 knockdown by various lipitoid variants was evaluated via quantitative real‐time polymerase chain reaction in human VF fibroblasts. Cytotoxicity was quantified via colorimetric assays. In vivo, a rabbit model of VF injury was employed to evaluate the temporal dynamics of Smad3 knockdown following injection of the L0‐siRNA complex.ResultsIn vitro, similar reductions in Smad3 expression were established by all lipitoid variants, with one exception. Sequence variants also exhibited similar nontoxic characteristics; no statistically significant differences in cell proliferation were observed. In vivo, Smad3 expression was significantly reduced in injured VFs following injection of L0‐complexed Smad3 siRNA at 1 day postinjection. Qualitative suppression of Smad3 expression persisted to 3 days following injury, but did not achieve statistical significance.ConclusionsIn spite of the chemical diversity of these peptoid transfection reagents, the sequence variants generally provided consistently efficient reductions in Smad3 expression. L0 yielded effective, yet temporally limited knockdown of Smad3 in vivo. Peptoids may provide a versatile platform for the discovery of siRNA delivery vehicles optimized for clinical application.Level of EvidenceNA

Elaborate Supramolecular Architectures Formed by Co-Assembly of Metal Species and Peptoid Macrocycles

“…Oligomers of N -substituted glycine units are known as peptoids and constitute an important family of synthetic peptidomimetic oligomers. − Over the past two decades, peptoids have garnered attention as a platform for the discovery of functional molecules due to their capacity to mimic bioactive peptides. − Peptoids notably differ from their α-peptide counterparts because of the presence of tertiary amide linkages between the monomer units. This feature endows peptoids with an exceptional resistance to proteolytic degradation.…”

Quantifying Polypeptoid Conformational Landscapes through Integrated Experiment and Simulation

“…They can now be routinely synthesized at gram scale, sequence-specifically up to 50 monomers in length in a process that eliminates the need for protection/deprotection procedures common in polypeptide synthesis, allowing access to a wide variety of chemistries . As such, they have been extensively explored for a broad range of applications, including as antifoulants, antimicrobials, − other therapeutics, delivery agents, , sensing applications such as stimuli-responsive materials, binder materials for batteries, crystallization modulators, and programmable self-assembly. − Many of these applications leverage the sequence-specificity of polypeptoids that has been shown to significantly modulate secondary − and self-assembled structures , and therefore function. Thus, advancement of polypeptoid-containing materials and the fundamental design rules that they follow requires elucidation of sequence–structure–function relationships.…”