A Novel Vector Strategy to Feasibilize Cellular Therapy for Heart Disease

摘要

ABSTRACT Recently, the potential of cellular therapy based upon genetic reprogramming of T cells via CAR-T technology has been explored for diseases of the heart, and the promise embodied in this strategy has captured popular and scientific imagination. However, in current clinical CAR-T cell therapy practice, extracorporeal methods must be applied, which represent a major time and cost barrier restricting wider implementation of this technology. Thus, robust methods to generate CAR-T in situ, within the patients, would greatly facilitate the practical application of this promising approach. For this, we propose to develop a robust gene delivery system consisting of a conjoined “SAd.AAV” nano-vector with multiple T cell-tropic adeno-associated viruses (AAVs) conjugated to a clinically approved, T-cell tropic simian (chimpanzee) adenovirus 36 (SAd) on its capsid's surface. Of note, both capsid-engineered SAd and AAVs are able to selectively target various tissues including T cells with high transduction efficiencies, and we hypothesized that SAd.AAV may therefore provide superior targeting through the combined effects of both engineered viral capsids targeting different receptors on the same tissue or cell type. Importantly, AAVs carrying single-stranded knock-in donor DNA templates have been widely shown to support high editing efficiency of homology directed repair (HDR). Furthermore, the robust but transient expression of gene editor by SAd also provides highly desirable “hit-and-run” gene editing reducing potential adverse effects associated with prolonged editor expression after the on-target editing is achieved. Therefore, by virtue of the advantages of each virus in gene editing, SAd.AAV potentially increases the tissue targeting specificity and efficiency and improves safety of existing CRISPR-Cas gene editing therapies. As a proof of concept, after constructing and characterizing the first T cell-targeted SAd.AAV, we plan to achieve efficient production of the heart disease-specific CAR-T cells in vivo with an SAd.AAV gene editing platform to knock-in a switchable CARi transgene in the T cells in vivo. A proof-of-principle demonstration of in vivo production of gene-edited switchable CARi-T cells will establish a key platform for follow-on studies of CARi-T interventions in murine models of heart diseases. We furthermore anticipate that the SAd.AAV can be rapidly redesigned to target a wide variety of clinically important organs relevant to the NHLBI for gene editing-based therapies.