FIG. 3.

The oxygen gradient and photodynamic treatment response of the 3D culture. (a) Expression levels of oxygen-responsive genes, in particular, the vascular endothelial growth factor (VEGF) and insulin-like growth factor-binding protein 3 (IGFBP3), were determined through real-time RT-PCR. Ct values relative to the ribosomal unit 18S were obtained and reported as fold increase (ΔΔCt) with respect to 2D cultures (N=2, n=3). (b) Human fibroblasts cultured on 2D and 3D were subjected to PDT, using different concentrations of TMPyP, PS, and light doses. The resulting cellular viability was assessed by MTT assay and compared between both culture models to study the effect of the drug and oxygen gradient (N=2, n=3). (c) MTT assay showed the survival pattern within the 3D construct during the photosensitization experiments. (d) The oxygen gradient was decoupled from the drug gradient by circulating an oxygen stream during PDT and the survival pattern was also evaluated by MTT assay. Error bars (a) and (b): SD. *p<0.05, **p<0.01, ***p<0.001. Color images available online at www.liebertpub.com/tea