Dendritic amphiphilic siRNA: Selective albumin binding, in vivo efficacy, and low toxicity
Hassan H. Fakih, Qi Tang, Ashley Summers, Minwook Shin, Julianna Buchwald, Rosemary Gagnon, Vignesh Hariharan, Dimas Echeverria, David Cooper, Jonathan K. Watts, Anastasia Khvorova, Hanadi F. Sleiman
Abstract
While an increasing number of siRNA therapies are reaching the market, the challenge of efficient extra-hepatic delivery continues to limit their full therapeutic potential. Drug delivery vehicles and hydrophobic conjugates are being employed to overcome the delivery bottleneck. Previously, we reported a novel dendritic conjugate that can be appended efficiently to oligonucleotides, allowing them to bind albumin with nanomolar affinity. Here, we explore the ability of this novel albumin-binding conjugate to improve the delivery of siRNAs in vivo. We demonstrate that the conjugate binds albumin exclusively in circulation, and extravasates to various organs, enabling effective gene silencing. Notably, we show that the conjugate achieves a balance between hydrophobicity and safety, as it significantly reduces the side effects associated with siRNA interactions with blood components, which are commonly observed in some hydrophobically conjugated siRNAs. In addition, it reduces siRNA monocyte uptake which may lead to cytokine/inflammatory responses. This work showcases the potential of using this dendritic conjugate as a selective albumin binding handle for the effective and safe delivery of nucleic acid therapeutics. We envision these properties may pave the way for new opportunities to overcome delivery hurdles of oligonucleotides in future applications.