Extracellular vesicles from AAV enhance inhaled gene therapy platform

Adeno-associated virus (AAV) vector has shown multiple clinical breakthroughs, but its clinical implementation in inhaled gene therapy remains elusive due to difficulty in transducing lung airway cells. Researchers from Johns Hopkins University School of Medicine demonstrate here AAV serotype 6 (AAV6) associated with extracellular vesicles (EVs) and secreted from vector-producing HEK-293 cells during vector preparation (EVAAV6) as a safe and highly efficacious gene delivery platform for inhaled gene therapy applications. Specifically, the researchers discovered that EVAAV6 provided markedly enhanced reporter transgene expression in mucus-covered air-liquid interface (ALI) cultures of primary human bronchial and nasal epithelial cells as well as in mouse lung airways compared to standard preparations of AAV6 alone. Of note, AAV6 has been previously shown to outperform other clinically tested AAV serotypes, including those approved by the FDA for treating non-lung diseases, in transducing ALI cultures of primary human airway cells. The researchers provide compelling experimental evidence that the superior performance of EVAAV6 is attributed to the ability of EV to facilitate mucus penetration and cellular entry/transduction of AAV6. The tight and stable linkage between AAV6 and EVs appears essential to exploit the benefits of EVs given that a physical mixture of individually prepared EVs and AAV6 failed to mediate EV-AAV6 interactions or to enhance gene transfer efficacy.

EVAAV6 provides enhanced reporter transgene expression in mucus-secreting ALI cultures of primary wild-type (WT) or cystic fibrosis (CF) HBE cells following apical administration

(a) Representative confocal images demonstrating reporter transgene expression in ALI cultures of primary WT or CF HBE cells treated with normal saline, AAV6, EVAAV6, or EV+AAV6. Green: YFP, Blue: nuclei. Image-based quantification of (b) coverage and (c) intensity of YFP transgene expression in the ALI cultures of primary WT (black) and CF (red) HBE cells treated with normal saline, AAV6, EVAAV6, or EV+AAV6. n.s.: no significance, ***p < 0.001, ****p < 0.0001 (two-way ANOVA).

Kwak G, Gololobova O, Sharma N, Caine C, Mazur M, Mulka K, West NE, Solomon GM, Cutting GR, Witwer KW, Rowe SM, Paulaitis M, Aslanidi G, Suk JS. (2023) Extracellular vesicles enhance pulmonary transduction of stably associated adeno-associated virus following intratracheal administration. J Extracell Vesicles 12(6):e12324. [article]

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