PMC

Triplex-mediated genomic modification in peripheral blood mononuclear cells (PBMCs) shows low off-target effects. (a) Blank nanopartcles (NPs) containing phosphate-buffered saline or CCR5-NPs containing donors and peptide nucleic acids were added to wild-type human PBMCs at a final concentration of 0.5 mg/ml. Twenty-four hours later, genomic DNA was isolated from the treated samples as well as untreated PBMCs, and targeted modification of the CCR5 gene was detected by AS-PCR. (b) Table depicting gene-targeted and off-targeted modification frequencies as determined by Illumina deep sequencing of the CCR5 and CCR2 gene in blank and CCR5-NP–treated PBMCS. The ratio of CCR5 to CCR2 targeted was determined by dividing the CCR5 modification frequency by the CCR2 modification frequency indicated in the table.

CCR5-nanoparticle (NP)–treated peripheral blood mononuclear cells (PBMCs) efficiently engraft NOD-scid IL2rγ-/^- mice. (a) Bar graph depicting the percentages of individual human lymphocytic populations in spleens of adult NOD-scid IL2rγ^-/- mice reconstituted with PBMCs that were untreated, treated with blank, or CCR5-targeted nanoparticles. %CD45 alone refers to the remainder of the CD45-positive cells that were not CD3⁺. A two-way analysis of variance with Tukey's multiple comparisons revealed no significant differences among the different groups. (b) Identification of targeted modification of the CCR5 gene in splenocytes of humanized mice reconstituted with human PBMCs (either untreated, treated with blank NPs, or with CCR5-NPs) at 4 weeks posttransplant. Allele-specific polymerase chain reaction was performed on the genomic DNA with the donor 1 primers.

Nucleic acid release from CCR5 nanoparticles. (a) Schematic of the CCR5 gene with the triplex-forming peptide nucleic acid, tcPNA-679, binding to the genomic DNA downstream of the two donor DNA oligonucleotides. K, lysine residue, J, pseudoisocytocine. (b) To calculate the kinetics of release of encapsulated nucleic acid, nanoparticles (NPs) were incubated in PBS at 37 °C and NP-free supernatants were collected for the analysis of total nucleic acid content by the absorbance at 260 nm at the indicated time points. At 48 hours, the residual nucleic acid in the NP pellet was extracted and the total nucleic acid load was calculated as a sum of absorbance obtained from the pellet and supernatant. Inset: SEM image of NPs. The average size of the NPs, calculated using the ImageJ software is depicted as mean ± SD. Scale bar: 500 nm.

Mice reconstituted with CCR5-targeted nanoparticle (NP)-treated peripheral blood mononuclear cells (PBMCs) resist HIV-1 challenge. (a) Experimental timeline: PBMCs from a donor heterozygous for the Δ32 mutation were treated with either blank or CCR5-NPs and transplanted into NOD-scid IL2rγ^-/- mice that were infected 2 weeks later with HIV-1_BaL. (b) Representative fluorescence-activated cell sorting plots depicting the CD4⁺ and CD8⁺ T cells from one mouse of each treatment group over time. (c) Flow cytometric evaluation of peripheral T cells (upper panel) and plasma viral copy numbers measured by the Amplicor test (lower panel). CD4⁺ T-cell ratios were calculated as a ratio of the entire CD3 population (CD3⁺CD4⁺:CD3⁺). The solid black line in the lower panel represents the limit of detection of the Amplicor test. Statistical significance was analyzed by repeated-measures one-way Anova followed by Tukey's multiple comparisons test. NS, not significant.

Characterization of CCR5 nanoparticles (NPs). (a) NPs containing the dye, coumarin 6 (C6) were added to wild-type peripheral blood mononuclear cells (PBMCs) (0.2 or 2 mg/ml), and fluorescence was measured by flow cytometric analysis 24 or 72 hours posttreatment. Cells were costained with anti-CD4-APC. (b) PBMCs treated as described above were quenched with trypan blue to assess internalized fluorescence versus external cell-associated fluorescence (uptake versus external association of NPs). Histograms of C6 fluorescence are shown. (c) Polyhydroxyalkanoate-activated PBMCs were treated with blank or CCR5-NPs at 0.2, 0.7, or 2.0 mg/ml, and culture supernatants were assayed for lactate dehydrogenase activity at 24 and 72 hours of culture. The positive control (lysed cells) for total lactate dehydrogenase release represents cells completely lysed with detergent. Repeated-measures one-way analysis of variance testing followed by a Dunnett's multiple comparisons test found no significant differences between the three groups treated with NPs and the untreated control cells (P > 0.05). ns, not significant. (d) Wild-type PBMCs were either untreated or treated with the indicated NPs and RNA was isolated at various time points. Quantitative reverse transcriptase polymerase chain reaction was performed to determine the mRNA levels of tumor necrosis factor-α or interleukin-6, and glyceraldehyde-3-phosphate dehydrogenase was used for normalization.