Abstract
Ex-vivo gene therapy using stem cells or T cells transduced by retroviral or lentiviral vectors has shown remarkable efficacy in the treatment of immunodeficiencies and cancer. However, the process is expensive, technically challenging, and not readily scalable to large patient populations, particularly in underdeveloped parts of the world. Direct in vivo gene therapy would avoid these issues, and such approaches with adeno-associated virus (AAV) vectors have been shown to be safe and efficacious in clinical trials for diseases affecting differentiated tissues such as the liver and CNS. However, the ability to transduce lymphocytes with AAV in vivo after systemic delivery has not been carefully explored. Here, we show that both standard and exosome-associated preparations of AAV8 vectors can effectively transduce a variety of immune cell populations including CD4+ T cells, CD8+ T cells, B cells, macrophages, and dendritic cells after systemic delivery in mice. We provide direct evidence of T cell transduction through the detection of AAV genomes and transgene mRNA, and show that intracellular and transmembrane proteins can be expressed. These findings establish the feasibility of AAV-mediated in vivo gene delivery to immune cells which will facilitate both basic and applied research towards the goal of direct in vivo gene immunotherapies.
Highlights
Gene therapy using ex-vivo transduction of patient-derived cells has revolutionized medicine, in the case of readily accessible blood hematopoietic stem cells or lymphocytes to treat immunodeficiencies or cancer[1,2,3]
We previously demonstrated that exosome-associated associated virus (AAV) vectors mediate higher transduction efficiencies of target organs compared to conventional AAV vectors when delivered into mice[15,16,17,18,19]
To determine whether these vectors could mediate in vivo transduction of immune cells when delivered systemically, we injected C57BL/6 mice intravenously with 3 × 1012 genome copies of an exo-AAV8 vector encoding a self-complementary green fluorescent protein (GFP) transgene expression cassette under control of the strong, ubiquitous chicken beta actin (CBA) promoter (AAV-sc-CBA-GFP) (Fig. 1A), or PBS as a control
Summary
Gene therapy using ex-vivo transduction of patient-derived cells has revolutionized medicine, in the case of readily accessible blood hematopoietic stem cells or lymphocytes to treat immunodeficiencies or cancer[1,2,3]. AAV vectors were thoroughly developed over the past 35 years and are demonstrating remarkable, life-changing efficacy in clinical trials for several diseases, including recently FDA approved treatments for a form of hereditary blindness and spinal muscular atrophy[5,6,7,8,9]. The majority of AAV-mediated gene therapies have focused on differentiated cells such as muscle[10,11], neurons, astrocytes[12], and liver[13]. We demonstrate that AAV8 vectors can mediate transgene expression in multiple immune cell types after systemic delivery in mice, providing an important proof of concept for developing these vectors for use in in vivo therapies
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