Resveratrol trimer enhances gene delivery to hematopoietic stem cells by reducing antiviral restriction at endosomes

Therapeutic gene deliveryto hematopoietic stem cells (HSCs) holds great potential as a life-saving treatment for a range of monogenic, oncologic, and infectious diseases. However, clinical gene therapy is severely limited by intrinsic HSC resistance to modification with lentiviral vectors (LVs), thus requiring high doses or repeat LV administration to achieve therapeutic gene correction. Here we show that temporary co-application of the cyclic resveratrol trimer caraphenol A enhances LV gene deliveryefficiency to human and non-human primate hematopoietic stem and progenitor cells. While significant ex vivo, this effect was most dramatically observed in human lineages derived from HSCs transplanted into immunodeficient mice. We further demonstrate that caraphenol A relieves restriction of LV transduction by altering the levels of interferon-induced transmembrane (IFITM) proteins IFITM2 and IFITM3 and their association with late endosomes, thus augmenting LV core endosomalescape. Caraphenol A-mediated IFITM downregulation did not alter the LV integration pattern or bias lineage differentiation. Taken together, these findings compellingly demonstrate that the pharmacologic modification of intrinsic immunerestriction factors is a promising and non-toxic approach for improving LV-mediated gene therapy.