Figure 3.

Microscopy image of live/dead stain (a), quantification of living and dead cells (b), and metabolic activity of the printed A549 cells (c). (a) Qualitative viability staining of living and dead A549 printed cells in the constructs at 48 h after irradiation using calcein-AM (live shown in green) and ethidium homodimer-1 (dead shown in red). Scale bar: 200 µm. The staining profile in the microscopy images mirrors the beam profile recorded on the film. (b) The estimated percentages of living and dead cells quantified using ImageJ. (c) The XTT test was used to assess the metabolic activity of A549 printed cells after exposure to different doses of radiotherapy at the relevant time points. Values were calculated as X-fold induction of lysis control. Data are presented as mean value ± SD; n = 3; * p < 0.05; ** p < 0.01; *** p < 0.001.