fig2

Figure 2. Future EV-based therapeutic options for the treatment of LSDs. Various EV engineering approaches and techniques can be used to optimize the therapeutic potential of EVs, including: (1) Cargo engineering, which can either be accomplished through exogenous loading techniques applied to the EVs post-isolation or endogenous loading techniques. In endogenous loading techniques, loading is accomplished through adaptation of the parental cell. Cargo can either be passively or actively loaded with the use of fusion proteins binding the cargo to EV-enriched proteins or transmembrane domains; (2) Surface engineering, which can improve circulation time of EVs, their tissue targeting potential and endosomal escape, which is needed for efficient intraluminal cargo delivery. Furthermore, EVs can be combined with synthetic nanoparticles. These hybrid systems can modulate the contents and functionality of both the particle surface and cargo. Future EV therapeutic modalities for LSDs potentially include; (3) Replacement therapies, which include enzyme-, and transporter-replacement therapy. These therapies can be loaded into EVs and delivered to target cells as mRNA or directly as protein; (4) Targeted drug delivery, for substrate reduction therapy (SRT), pharmacological chaperon therapy (PCT) and potentially drug induced autophagy regulation; (5) Gene therapy & gene editing, which includes loading of constructs such as plasmid DNA, mRNA, miRNA and siRNA for gene addition or modulation. Moreover, EVs could be engineered to contain CRISPR/Cas or Prime editing constructs in the form of plasmid DNA, mRNA or RNP complexes; and (6) Other therapies, which include unmodified or engineered EVs for adjuvant therapy, including immune-modulatory, regenerative therapy and autophagy regulation.