Josh Leonard

@josh-leonard.bsky.social

My group seeks to grow the field of synthetic biology, with a focus on making advanced gene and cell therapies useful and available to more people. Prof at Northwestern Chem & Biol. Engineering and Center for Synthetic Biology @TheLeonardLab on Twitter

I'm excited to share this new story led by @jdboucher.bsky.social in which we solve a longstanding problem challenging the development of a promising class of gene delivery vehicle. www.biorxiv.org/content/10.1...

Distinguishing Protein and Gene Delivery Enables Characterization and Bioengineering of Extracellular Vesicle-Adeno-Associated Virus Vectors

Adeno-associated virus (AAV) gene therapies have achieved clinical success, with multiple products reaching regulatory approval. Encapsulation of AAV vectors within engineered extracellular vesicles (EVs) is an emerging strategy which could help overcome challenges including pre-existing anti-capsid immunity and the need for controlling targeting and tropism. To guide the development of EV-AAV technologies, we developed an assay for quantifying and controlling for the contribution of pseudotransduction to evaluations of EV-AAV-mediated gene delivery. We developed an AAV vector that switches its transgene output from one reporter to another when acted upon by Cre recombinase expressed in a recipient cell. Using this platform, we investigated EV-AAV transduction as a function of various engineered EV surface modifications. For actively endocytic cells (HEK293FTs), modifications that enhance EV uptake and membrane fusion influence protein delivery but not gene delivery. Conversely, in less endocytic Jurkat T cells, modifications enhancing EV uptake improved both protein and gene delivery. These conclusions held across multiple AAV serotypes. Our results resolve apparent conflicts in prior reports and suggest that effects of enhancing uptake and membrane fusion of EV-AAV vectors are recipient cell type specific. The methods developed here unambiguously dissect EV-AAV transduction mechanisms and can guide future bioengineering of EV-AAV vectors. ### Competing Interest Statement J.N.L., D.M.S. and H.I.E. have financial interests in Syenex Inc., which could potentially benefit from the outcomes of this research. National Institute of General Medical Sciences, T32GM008449 National Science Foundation, DGE-1842165, ECCS-2025633, DMR-2308691 National Cancer Institute, CA060553

biorxiv.org

Could one envision a synthetic receptor technology that is fully programmable, able to detect diverse extracellular antigens – both soluble and cell-attached – and convert that recognition into a wide range of intracellular responses, from gene expression and real-time fluorescence to modulation..

Every cell in the living world constantly sheds virus-size particles, and these “EVs” are useful for biotechnology. Here we address a key unmet need in EV bioengineering research: counting surface features (accurately) 1/3 www.biorxiv.org/content/10.1...

HaloTag display enables quantitative single-particle characterization and functionalization of engin...

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