FIGURE 4.

Viability of OHS spheroids treated with dual alpha solutions. (A) Viability of spheroids 48 h, 72 h, and 12 days after 24 h incubation with 1–10 kBq/ml of ²²⁴Ra/²¹²Pb, ²²⁴Ra/²¹²Pb-TCMC-TP-3 (specific activity of 2.3 MBq/mg) or ²²⁴Ra/²¹²Pb-TCMC-trastuzumab (TRA, specific activity of 3.7 MBq/mg). The relative viability was calculated by dividing the viability of the treated spheroids by the viability of untreated spheroids (0 kBq/ml) at each activity concentration. (B) At day 12, spheroids were stained with fluorescein diacetate and propidium iodide to observe live and dead cells, respectively, before spheroids were imaged (4× magnification) using an inverted Axiovert 200M microscope (Carl Zeiss AG, Jena, Germany), scale bar = 500 μm. All spheroids were analyzed with the AxioVision Rel. 4.8 software (Carl Zeiss AG). Spheroids were 60 ± 5.0 × 10⁶ μm³ at day 0.