A Light-Triggerable Nanoparticle Library for the Controlled Release of Non-Coding RNAs.

RNA-based therapies offer a wide range of therapeutic interventions including the treatment of skin diseases; however, the strategies to efficiently deliver these biomolecules are still limited due to obstacles related to the cellular uptake and cytoplasmic delivery. Herein, we report the synthesis of a triggerable polymeric nanoparticle (NP) library composed of 160 formulations, presenting physico-chemical diversity and differential responsiveness to light. Six formulations were more efficient (up to 500 %) than commercially available lipofectamine in gene-knockdown activity. These formulations showed differential internalization by skin cells and the endosomal escape was rapid (minutes range). The NPs were effective in the release of siRNA and miRNA. Acute skin wounds treated with the top hit NP complexed with miRNA-150-5p healed faster than wounds treated with scrambled miRNA. Light-activatable NPs offer a new strategy to topically deliver non-coding RNAs.

A chemical approach for the synthesis of the DNA-binding domain of the oncoprotein MYC.

We describe the first chemical synthesis of a functional mutant of the DNA binding domain of the oncoprotein MYC, using two alternative strategies which involve either one or two Native Chemical Ligations (NCLs). Both routes allowed the efficient synthesis of a miniprotein which is capable of heterodimerizing with MAX, and replicate the DNA binding of the native protein. The versatility of the reported synthetic approach enabled the straightforward preparation of MYC and Omomyc analogues, as well as fluorescently labeled derivatives.

Nanoparticles Conjugated with Photocleavable Linkers for the Intracellular Delivery of Biomolecules.

We report the synthesis and characterization of phototriggerable polymeric nanoparticles (NPs) for the intracellular delivery of small molecules and proteins to modulate cell activity. For that purpose, several photocleavable linkers have been prepared providing diverse functional groups as anchoring points for biomolecules.

A light-triggerable formulation to control the stability of pro-angiogenic transcription factor hypoxia inducible factor-1α (HIF-1α).

The control of vascular remodeling mediated by transcription factor HIF-1α is critical in the treatment of several diseases including cancer, retinopathies, chronic wounds, and ischemic heart disease, among others. Gene silencing using a small interfering RNA (siRNA) is a promising therapeutic strategy to regulate HIF-1α; however, the delivery systems developed so far have limited endothelial targeting and efficiency. Herein, we have synthesized a light-triggerable polymeric nanoparticle (NP) library composed of 110 formulations which showed variable morphology, charge and disassembly rates after UV exposure. More than 35% of the formulations of the library were more efficient in gene knockdown than the siRNA delivered by a commercial transfection agent (lipofectamine RNAiMAX). The most efficient siRNA delivery formulations were tested against different cell types to identify one with preferential targeting to endothelial cells. Using a two-step methodology, we have identified a formulation that shows exquisite targeting to endothelial cells and is able to deliver more efficiently the siRNA that modulates HIF-1α than commercial transfection agents. Overall, the strategy reported here increases the specificity for tissue regulation and the efficiency for the intracellular delivery of siRNAs.

The Kinetics of Small Extracellular Vesicle Delivery Impacts Skin Tissue Regeneration.

Small extracellular vesicles (SEVs) offer a promising strategy for tissue regeneration, yet their short lifetime at the injured tissue limits their efficacy. Here, we show that kinetics of SEV delivery impacts tissue regeneration at tissue, cellular, and molecular levels. We show that multiple carefully timed applications of SEVs had superior regeneration than a single dose of the same total concentration of SEVs. Importantly, diabetic and non-diabetic wounds treated with a single time point dose of an injectable light-triggerable hydrogel containing SEVs demonstrated a robust increase in closure kinetics relative to wounds treated with a single or multiple doses of SEVs or platelet-derived growth factor BB, an FDA-approved wound regenerative therapy. The pro-healing activity of released SEVs was mediated at the tissue/cell level by an increase in skin neovascularization and re-epithelization and at the molecular level by an alteration in the expression of 7 miRNAs at different times during wound healing. This includes an alteration of has-miR-150-5p, identified here to be important for skin regeneration.

Stimuli-responsive selection of target DNA sequences by synthetic bZIP peptides.

One of the strategies used by nature to regulate gene expression relies on the stimuli-controlled combination of DNA-binding proteins. This in turn determines the target-binding site within the genome, and thereby whether a particular gene is activated or repressed. Here we demonstrate how a designed basic region leucine zipper-based peptide can be directed towards two different DNA sequences depending on its dimerization arrangement. While the monomeric peptide is non-functional, a C-terminal metallo-dimer recognizes the natural ATF/CREB-binding site (5'-ATGA cg TCAT-3'), and a N-terminal disulphide dimer binds preferentially to the swapped sequence (5'-TCAT cg ATGA-3'). As the dimerization mode can be efficiently controlled by appropriate external reagents, it is possible to reversibly drive the peptide to either DNA site in response to such specific inputs. This represents the first example of a designed molecule that can bind to more than one specific DNA sequence depending on changes in its environment.