Overexpression of ER Protein Processing and Apoptosis Regulator Genes in Human Embryonic Kidney 293 Cells Improves Gene Therapy Vectors Production

Gammaretroviral and lentiviral vectors (gamma-RV and LV) are among the most used vectors in gene therapy. Currently, human embryonic kidney (HEK) 293 cells, the manufacture platform of choice for these vectors, provide low transducing particle yields, challenging their therapeutic applications and commercialization. This work studies metabolic pathways, focusing on endoplasmic reticulum (ER) protein processing and anti-apoptotic mechanisms, influencing vector productivity in HEK 293 cell substrates. To that end, four candidate genes-protein disulfide isomerase family A member 2 gene, heat shock protein family A (Hsp70) member 5 gene, X-box binding protein 1 gene (ER protein processing), and B-cell lymphoma 2 protein gene (anti-apoptotic)-are individually stably expressed in the cells. How their overexpression level influence vector yields is analyzed by establishing cell populations with incremental genomic copies of each. gamma-RV volumetric productivity increases up to 97% when overexpressing ER protein processing genes. LV volumetric production increases 53% when overexpressing the anti-apoptotic gene. Improvements are associated with higher cell specific productivities and dependent on gene overexpression level, highlighting the importance of fine-tuning gene expression. Overall, this work discloses gene engineering targets enabling efficient gene therapy product manufacture showing that ER protein processing and anti-apoptotic pathways are pivotal to producer cell performance.