Figure 2.

The Transfection Levels and Biocompatibility of A_nP_n in Human Astrocytes are Affected by pH and Number of Arginine Residues

Arginine-modified PEI polymer derivatives synthesized by method S1 or S2 containing 1, 5, or 7 arginine residues (A₁, A₅, A₇) and 10 polyethylene glycol (PEG) (P₁₀) residues/PEI molecule were mixed with pLuc in a 2:1 ratio. Human astrocytes (150,000/well) were treated with A_nP_n polyplexes. After 3 hr, polyplex containing-media was removed, and fresh culture medium was added. (A) Luciferase, (B) LDH, and (C) metabolic activities were measured 48 hr post-treatment. Data represent mean ± SEM for three donors with a minimum of triplicate determinations/donor (*p < 0.05, ***p < 0.001). In parallel, astrocytes were immunostained for astrocyte-specific glial fibrillary acidic protein (GFAP; red) and nuclear dye DAPI (blue). (D) Untreated control, (E) S1 A₁P₁₀, (F) S1 A₅P₁₀, (G) S1 A₇P₁₀, (H) S2 A₁P₁₀, (I) S2 A₅P₁₀, and (J) S2 A₇P₁₀. Arrows indicate astrocytes with distinct cytoplasmic pDNA staining in endosomes. Representative donor images from four independent donors are shown. Original magnification ×200.