We are pleased to announce that Prof. Elita Montanari (Università degli studi Roma Tre, Italy) will join Targeting Extracellular Vesicles 2026 as a speaker.

FDA-approved carriers delivering nucleic acids to the retina are limited. The primary strategy uses adeno-associated viruses (AAVs) to deliver DNA. However, this approach comes with limited gene-packaging capacity, immunogenicity, and low compliance. On the other hand, synthetic lipid nanoparticles (LNPs) may elicit inflammatory responses. As an alternative, we have developed a non-viral carrier based on human blood-derived extracellular vesicles (hb-EVs) for safely delivering exogenous messenger RNAs (mRNAs) to retinal cells. Three different kinds of hb-EVs have been investigated. All hb-EVs spontaneously hemi-fuse with lipid nanovectors (LNVs) carrying mRNA, forming hybrid EVs (hb-hEVs). mRNA can be loaded into all three types of hb-hEVs at levels exceeding 90%, with at least 85% hybridization between EVs and LNVs. All three hb-hEVs are nontoxic to human retinal pigment epithelial cells (ARPE-19) but differ in uptake and transfection capacity, demonstrating natural tropism. One type of hb-hEV (hb-hEV-1) exhibits the greatest uptake and reproducible transfection efficacy in cells compared with the other two; therefore, it has been selected and tested for its transduction efficiency in retinal cells of healthy mice following subretinal and intravitreal injections. hb-hEV-1 carrying mCherry mRNA displays a safe profile and primarily transfects retinal pigment epithelium (RPE) cells after subretinal administration, as well as some Müller glia (MG) and RPE cells after intravitreal administration. The outcome suggests that hybridizing suitable EVs with LNVs creates a modular platform that enables efficient retinal mRNA delivery across routes of administration. It allows for transfection of the deeper retinal cell layers, even via intravitreal injection, a rare feat that might open significant therapeutic opportunities for several untreatable genetic eye diseases and pave the way for safe, targeted delivery and semi-autologous, personalized medicine. Last but not least, this research also elucidates a highly efficient and versatile strategy for loading mRNAs into natural EVs. This approach yields mRNA LE greater than 90%, while retaining EV functionality. Such a strategy can ideally be applied to all natural EVs, unlocking their investigation as gene-therapy carriers across a wide range of medical applications.