Staurosporine Increases Lentiviral Vector Transduction Efficiency of Human Hematopoietic Stem and Progenitor Cells.

Lentiviral vector (LVV)-mediated transduction of human CD34 hematopoietic stem and progenitor cells (HSPCs) holds tremendous promise for the treatment of monogenic hematological diseases. This approach requires the generation of a sufficient proportion of gene-modified cells. We identified staurosporine, a serine/threonine kinase inhibitor, as a small molecule that could be added to the transduction process to increase the proportion of genetically modified HSPCs by overcoming a LVV entry barrier. Staurosporine increased vector copy number (VCN) approximately 2-fold when added to mobilized peripheral blood (mPB) CD34 cells prior to transduction. Limited staurosporine treatment did not affect viability of cells post-transduction, and there was no difference in colony formation compared to vehicle-treated cells. Xenotransplantation studies identified a statistically significant increase in VCN in engrafted human cells in mouse bone marrow at 4 months post-transplantation compared to vehicle-treated cells. Prostaglandin E (PGE) is known to increase transduction efficiency of HSPCs through a different mechanism. Combining staurosporine and PGE resulted in further enhancement of transduction efficiency, particularly in short-term HSPCs. The combinatorial use of small molecules, such as staurosporine and PGE, to enhance LVV transduction of human CD34 cells is a promising method to improve transduction efficiency and subsequent potential therapeutic benefit of gene therapy drug products.