Gene Delivery to Human B-Precursor Acute Lymphoblastic Leukemia Cells

Autologous leukemia cells engineered to express immune-stimulatingmolecules may be used to elicit antileukemia immune responses. Genedelivery to human B-precursor acute lymphoblastic leukemia (ALL) cellswas investigated using the enhanced green fluorescent protein (EGFP) asa reporter gene, measured by flow cytometry. Transfection of the Nalm-6and Reh B-precursor ALL leukemia cell lines with an expression plasmidwas investigated using lipofection, electroporation, and a polycationiccompound. Only the liposomal compound Cellfectin showed significantgene transfer (3.9% to 12% for Nalm-6 cells and 3.1% to 5% for Rehcells). Transduction with gibbon-ape leukemia virus pseudotyped Moloneymurine leukemia virus (MoMuLV)-based retrovirus vectors wasinvestigated in various settings. Cocultivation of ALL cell lines withpackaging cell lines showed the highest transduction efficiency forretroviral gene transfer (40.1% to 87.5% for Nalm-6 cells and 0.3%to 9% for Reh cells), followed by transduction with viral supernatant on the recombinant fibronectin fragment CH-296 (13% to 35.5% for Nalm-6 cells and 0.4% to 6% Reh cells), transduction on human bonemarrow stroma monolayers (3.2% to 13.3% for Nalm-6 cells and 0% to0.2% Reh cells), and in suspension with protamine sulfate (0.7% to3.1% for Nalm-6 cells and 0% for Reh cells). Transduction of bothNalm-6 and Reh cells with human immunodeficiency virus-type 1 (HIV-1)-based lentiviral vectors pseudotyped with the vesicular stomatitis virus-G envelope produced the best gene transfer efficiency, transducing greater than 90% of both cell lines. Gene delivery intoprimary human B-precursor ALL cells from patients was then investigatedusing MoMuLV-based retrovirus vectors and HIV-1-based lentivirusvectors. Both vectors transduced the primary B-precursor ALL cells withhigh efficiencies. These studies may be applied for investigating genedelivery into primary human B-precursor ALL cells to be used forimmunotherapy.