Fig. 3. Evaluation of PEI-al/pDNA properties in MC3T3-E1 cells in vitro. (A) Fluorescent microscopy images of MC3T3-E1 cells transfected with PEI/pEGFP and PEI-al/pEGFP complexes at different nanocomposite/pEGFP w/w. Bright field of MC3T3-E1. (B–D) EGFP expression in MC3T3-E1 cells transfected by PEI/pEGFP (w/w = 1 : 1) and PEI-al/pEGFP (w/w = 2 : 1 and 3 : 1) complexes. (E) Viability of MC3T3-E1 cells transfected with PEI/pBMP-2 and PEI-al/pBMP-2 complexes at w/w of 0, 0.5 : 1, 1 : 1, 2 : 1 and 3 : 1. (F) Expression of BMP-2 mRNA in MC3T3-E1 cells evaluated by qPCR. (G) Release of human BMP-2 protein from PEI-al/pBMP-2-transfected MC3T3-E1 cells on days 2, 4, 6, 8, 10, 12 and 14. Data are reported as mean ± SD (n = 3), *P < 0.05 and **P < 0.01.