ShRNA-mediated knock-down of CD200 using the self-assembled nanoparticle-forming derivative of polyethylenimine

ShRNA-mediated silencing strategy is considered to be a potent therapeutic approach. The present study aimed to assess the ability of the previously prepared polyethylenimine (PEI) derivative for the shRNA knock-down of the CD200 gene on the cells obtained from the patients with chronic lymphocytic leukemia (CLL). Since there are several investigations regarding the role of CD200 over-expression in the progression of several malignancies (e.g., CLL), polyplexes were prepared using succinylated PEI and the plasmid encoding anti-CD200 shRNA. The ability of the nanoparticles for CD200 silencing at the levels of protein and mRNA, as well as the apoptotic effects induced by unmodified PEI and its derivative, were evaluated. Conjugation of succinic acid using the primary amines of PEI reduced the cell-induced toxicity of the polymer. Under such circumstances, 92.1% of the cells remained alive after treatment with the nanoparticles based on modified PEI. In addition, CD200 knock-down evaluations demonstrated a 50% reduction in the expression of the gene in the samples obtained from patients with CLL, while using the same formulation on the cells obtained from healthy donors decreased the CD200+ cells up to 10%. The results of CD200 silencing at the mRNA level revealed that the shRNA formulation could reduce the CD200 level in the cells of the patients by 3.2-6.06-fold relative to the cells transfected with non-effective, scrambled shRNA. Our findings supported the application of succinylated PEI for the down-regulation of the CD200 gene in the upcoming attempts to develop nano-carriers for gene therapy.