Lentiviral Vectors Escape Innate Sensing but Trigger p53 In Human Hematopoietic Stem Cells

In the context of lentiviral vector (LV)-mediated gene correction of hematopoietic stem and progenitor cells (HSPC), the viral origin of LV could trigger cellular responses with potential functional consequences that have not been investigated to date. Here, a time-course genome-wide transcriptional profiling of transduced human HSPC reveals a remarkably limited impact of LV on cellular gene expression, supporting some stealth features of the vector. In particular, LV efficiently escaped innate immune sensing that instead led to robust type I IFN signaling upon transduction with a gamma-retroviral vector. However, recognition of LV DNA prior to integration did trigger DNA damage responses that were activated also by non-integrating Adeno-associated vector DNA. As a consequence of this transient p53 activation, transduced HSPC showed increased apoptosis in vitro and reduced engraftment in vivo at limiting cell doses, but no long-term impact or competitive disadvantage were detected. Pharmacological inhibition of the LV signaling partially rescued both apoptosis and engraftment, potentially providing a novel strategy to further dampen the impact of ex vivo gene therapy on HSPC. Overall, our results shed light on the molecular mechanisms of viral vector sensing in HSPC and provide critical insight for the development of more stealth gene therapy strategies. Overall design: RNA-seq of CD34+ cells transduced with different lentiviral vectors. Multiple time points were profiled in biological triplicates.