Red Blood Cell Anchoring Enables Targeted Transduction and Re‐Administration of AAV‐Mediated Gene Therapy

Abstract Adeno‐associated virus (AAV)‐mediated gene therapy is a promising therapeutic modality for curing many diseases including monogenic diseases. However, limited tissue‐targeting and restricted re‐administration due to the vector immunogenicity largely restrict its therapeutic potential. Here, using a red blood cell (RBC) as the carrier vehicle for AAV is demonstrated to improve its tissue‐targeted transduction and enable its re‐administration. Anchoring AAV to the RBC surface minimally affected its infectability toward endothelial cells. Meanwhile, AAV anchored onto RBCs is predominantly delivered to and shows efficient transduction in the lungs by virtue of the biophysical features of RBCs. RBC‐anchored AAVs lead to a four‐ to five‐fold enhancement in target gene expression in the lungsas compared to free AAVs following a single‐ or dual‐dosing regimen. While RBC anchoring does not prevent the induction of adaptive immune responses against AAV, it results in successful transgene expression upon re‐administration following prior AAV exposure. The ability to re‐administer is partially attributed to the delayed and reduced AAV neutralization by neutralizing antibodies, resulting from the combination of limited exposure of physically confined AAVs and the short time required to reach the lungs. This study's findings suggest that the RBC‐mediated approach is a promising strategy for repetitive, targeted AAV gene therapy.