Detailed comparison of retroviral vectors and promoter configurations for stable and high transgene expression in human induced pluripotent stem cells

ABSTRACT: Correction of patient-specific induced pluripotent stem cells (iPSC) upon gene delivery through retroviral vectors offers new treatment perspectives for monogenetic diseases. Gene-modified iPSC clones can be screened for safe integration sites and differentiated into transplantable cells of interest. However, the current bottleneck is epigenetic vector silencing. In order to identify the most suitable retroviral expression system in iPSC, we systematically compared vectors from different retroviral genera, different promoters and their combination with ubiquitous chromatin opening elements (UCOE), and several envelope pseudotypes. Lentiviral vectors (LV) pseudotyped with VSV-G were superior to gammaretroviral and alpharetroviral vectors and other envelopes tested. The short elongation factor 1α (EFS) promoter mediated the most robust expression, while expression levels were lower from the potent but more silencing-prone spleen focus forming virus (SFFV) promoter. Both full length (A2UCOE) and minimal (CBX3) UCOE juxtaposed to two physiological and one viral promoter reduced transgene silencing with equal efficiency. However, a promoter-specific decline in expression levels was not entirely prevented. Upon differentiation of transgene-positive iPSC into endothelial cells, A2UCOE.EFS and CBX3.EFS vectors maintained highest transgene expression in a larger fraction of cells as compared to all other constructs tested here. The function of UCOE diminished but did not fully counteract vector silencing and possibilities for improvements remain. Nevertheless, the CBX3.EFS in a LV background exhibited the most promising promoter and vector configuration for both high titer production and long-term genetic modification of human iPSC and their progeny.

ORGANISM(S): Homo sapiens

PROVIDER: GSE94157 | GEO | 2018/01/01

SECONDARY ACCESSION(S): PRJNA369099

REPOSITORIES: GEO