Abstract
The clinical impact of gene therapies is constrained by poor delivery to target tissues beyond the liver after intravenous administration. Current molecular targeting strategies, such as capsid engineering or gene-carrier surface modification, have achieved only limited success due to their inability to overcome the hierarchical barriers from injection to deep tissue transduction. Here, we introduce a Multiscale Approach using RBC-mediated hitchhiking and Vascular Endothelium Leakage (MARVEL), which integrates red blood cell hitchhiking with VEGF-induced vascular permeabilization to enhance accumulation and penetration of cargoes. Using adeno-associated viruses (AAVs) as a model, MARVEL markedly increases AAV localization in the lungs, improves endothelial transcytosis, and enables gene expression in deeper tissue layers while maintaining a favorable safety profile. We further demonstrate that MARVEL can be adopted into an in situ hitchhiking approach, bypassing the need for ex vivo formulation. MARVEL provides a scalable strategy to address long-standing delivery challenges in gene therapy.