Functional siRNA Delivery by Extracellular Vesicle–Liposome Hybrid Nanoparticles

Abstract

The therapeutic use of RNA interference is limited by the inability of siRNA molecules to reach their site of action, the cytosol of target cells. Lipid nanoparticles, including liposomes, are commonly employed as siRNA carrier systems to overcome this hurdle, although their widespread use remains limited due to a lack of delivery efficiency. More recently, nature's own carriers of RNA, extracellular vesicles (EVs), are increasingly being considered as alternative siRNA delivery vehicles due to their intrinsic properties. However, they are difficult to load with exogenous cargo. Here, EV-liposome hybrid nanoparticles (hybrids) are prepared and evaluated as an alternative delivery system combining properties of both liposomes and EVs. It is shown that hybrids are spherical particles encapsulating siRNA, contain EV-surface makers, and functionally deliver siRNA to different cell types. The functional behavior of hybrids, in terms of cellular uptake, toxicity, and gene-silencing efficacy, is altered as compared to liposomes and varies among recipient cell types. Moreover, hybrids produced with cardiac progenitor cell (CPC) derived-EVs retain functional properties attributed to CPC-EVs such as activation of endothelial signaling and migration. To conclude, hybrids combine benefits of both synthetic and biological drug delivery systems and might serve as future therapeutic carriers of siRNA.

Engineering Cardiac Small Extracellular Vesicle-Derived Vehicles with Thin-Film Hydration for Customized microRNA Loading

“…To address some of the limitations of purely artificial SUVs, hybrids of SUVs and sEVs were created utilizing TFH and extrusion with sEVs. Specifically, hybrids designed from CPC-sEVs increased the activity of AKT, a downstream target of miR-126 [43]. In this study, we take this idea of hybrids one step further, by utilizing a completely sEV-based membrane to form our sEV-scale ELVs (Figure 2).…”

Extracellular Vesicle-Based Hybrid Systems for Advanced Drug Delivery

“…Given the membranous composition of EVs, lipids present in sNPs, such as lipid nanoparticles or liposomes, can be merged into the EV lipid bilayer by extruding EVs and sNPs together through membranes with defined pore sizes. As an example, it has been recently shown that EVs and siRNA can be incorporated at the hydration step of the lipid film hydration method for the preparation of liposomes, which is followed by subsequent extrusion steps to form stable EV-liposome hybrids loaded with siRNA [49]. Interestingly, although the encapsulation efficiency of siRNA into hybrids was slightly decreased as compared to liposomes, it was still substantially higher than what has been demonstrated for other EV-loading strategies [49].…”

“…Extrusion seems to be the preferred method to produce EV-based hybrids with synthetic lipids [47][48][49][50][51]. Given the membranous composition of EVs, lipids present in sNPs, such as lipid nanoparticles or liposomes, can be merged into the EV lipid bilayer by extruding EVs and sNPs together through membranes with defined pore sizes.…”

“…As an example, it has been recently shown that EVs and siRNA can be incorporated at the hydration step of the lipid film hydration method for the preparation of liposomes, which is followed by subsequent extrusion steps to form stable EV-liposome hybrids loaded with siRNA [49]. Interestingly, although the encapsulation efficiency of siRNA into hybrids was slightly decreased as compared to liposomes, it was still substantially higher than what has been demonstrated for other EV-loading strategies [49]. The combination of sonication and extrusion has also been employed to produce EV-based hybrid systems [47,51].…”

Increasing the Therapeutic Efficacy of Extracellular Vesicles From the Antigen-Specific Antibody and Light Chain Perspective

“…Similarly, our observations suggested the ability of EVs to bind freely circulating miRNAs ( Bryniarski et al, 2015 ). This could likely be applied in small interfering RNA (siRNA) delivery, as can recently developed EV-liposome hybrid nanoparticles ( Evers et al, 2021 ). These findings also imply that EVs may constitute physiological nanocarriers for removing other molecules from the circulation.…”