Figure 2.

Gene delivery regulated with the total density of RGD peptides (N_RGD) presented from the gel matrix to which cells adhered. Microscopic images show the increases in the cellular uptake of the rhodamine-labeled pDNA condensates with N_RGD (a). White lines in photomicrographs represent the border of cells adhered to the gel matrix. The efficiency of gene transfer, quantified from the photomicrographs, linearly increased with N_RGD (R² = 0.94) (b). The gene expression level (● in c) and the gene expression level normalized to the average surface area of cells (■ in c) also linearly increased with N_RGD (R² = 0.94). More than 20 cells at each condition were used for the quantitative analysis of the efficiency of gene transfer. Differences in the values in (b)–(c) for cells adhered to gels with the highest N_RGD versus the two other conditions were statistically significant (p < 0.05). The gene expression level in (c) was normalized to the gene expression level attained from cells cultured on gels with N_RGD of 3 × 10⁹/mm². Data points and error bars represent the mean and standard deviation from four independent experiments.