B7 - Musculo-skeletal Diseases
1150: Fibrosis Restricts rAAV Gene Transfer and Can be Relieved by FAP-Specific CAR T Cells in a Murine Model of Duchenne Muscular Dystrophy
Type: Poster Session
Poster Board Number: 1150
Presentation Details
Session Title: Thursday Posters: Musculo-Skeletal Diseases
Duchenne muscular dystrophy (DMD) is a muscle disorder that progressively weakens skeletal and cardiac muscles and causes fibrosis in muscle tissues. In the DBA2mdx mouse model of severe DMD, rapid and intense fibrosis was observed, characterized by dense collagen deposits in skeletal muscles, with over-expression of the FAP and Col3 genes in the TA, GA, EDL muscles at 2, 3, and 4 months of age compared to their aged-matched DBA2 littermates. It is hypothesized that fibrosis may limit the effectiveness of gene transfer therapy in DMD but direct evidence is lacking and strategies to reduce skeletal muscle fibrosis are limited. Because FAP-specific CAR-T cells were shown to reduce drug-induced cardiac fibrosis in mice, we tested whether FAP-specific CAR-T cells could also reduce the broad and spontaneously occurring skeletal muscle fibrosis in DBA2mdx mice. A FAP-CAR lentiviral vector (LV) encoding a third-generation CAR with an mFAP-specific ScFv was generated and validated on FAP-overexpressing 3T3 cells. The FAP-CAR LV was used to generate FAP-specific cytotoxic T cells from DBA2 spleen cells. Two consecutive administrations of FAP-CAR T cells to DBA2mdx mice reduced the histological and molecular biomarkers of fibrosis, as measured 2 weeks post-cell injection. When FAP-CAR T cells were injected into DBA2mdx mice before the intravenous administration of rAAV9 encoding a microdystrophin (5xE12 vg/Kg), there was an increased gene transfer efficacy as demonstrated by higher viral genome and transgene expression in TA and EDL muscles compared to controls. These results demonstrate for the first time that fibrosis acts as a restriction to rAAV gene transfer and provide a novel therapeutic option to treat muscular dystrophies by combining gene therapy and immunotherapy. MF and SA contributed equally. IR and AG are co-senior authors of this study.
Plain Language Summary
Duchenne muscular dystrophy (DMD) is a muscle disease of genetic origin, characterized by a progressive loss of muscle function and accompanied by fibrosis of muscle tissues. Fibrosis not only aggravates the disease but may also hamper its treatment by gene therapy. We developed a new approach based on genetically-engineered immune killer cells, the so-called CAR T cells, directed against a highly-expressed fibrosis marker. In mice with DMD, the injection of such fibrosis-specific killer CAR T cells reduced the hallmarks of fibrosis as demonstrated by microscopic and molecular analyses of muscle tissues. When fibrosis-specific CAR T cells were injected to DMD mice prior to gene therapy, higher levels of gene delivery and of gene expression were obtained, demonstrating that fibrosis restrict the efficacy of gene therapy in muscle. Further studies are warranted to use CAR-T cells to improve the treatment DMD.
Maxime Ferrand1, Sonia Albini1, Céline Rocca1, Valentina Buffa1, Isabelle Richard1, Anne Galy1,2
1UMR_S951 Integrare Research Unit, Genethon, Evry-Courcouronnes, France,2Art-tg, Inserm, Corbeil-Essonnes, France"
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