Background: 3D cellular structures have been considered the following step in the evaluation of drugs penetration after 2D cultures since they are more physiologically representative in cancer cell biology. Here the penetration capabilities of Pt (IV)-loaded ultrasmall iron oxide nanoparticles in 143B osteosarcoma multicellular spheroids of different sizes is conducted by a multidimensional quantitative approach. Single cell (SC) and imaging techniques (laser ablation, LA) coupled to inductively coupled plasma-mass spectrometry (ICP-MS) are used to visualize their penetration pathways and distribution in comparison to those of cisplatin.
Results: The analysis of Pt in disaggregated individual cells from spheroids shows levels of incorporation dependent on the spheroid surface to volume ratio and considerably higher than those observed for cisplatin. These results in combination with the total Pt determination in the complete spheroids reveal a preferential transcellular incorporation pathway of the Pt(IV)-loaded NPs. Elemental imaging by LA-ICP-MS shows the co-localization of Pt/Fe in hot spots at distances up to 100 μm from the spheroid surface reaching concentrations of Pt up to 200 μg g-1 when exposed to Pt(IV)-loaded NPs. A more homogeneous distribution all along the spheroid is observed in the cisplatin-treated models.
Significance: The multidimensional ICP-MS based analytical methodology developed through this work offers a generalizable approach to quantitatively study the tissue penetration of nano-transported drugs to be applied in the design of nanoparticles with high accumulation at a target site.
Keywords: ICP-MS; Imaging; Osteosarcoma; Pt (IV)-Loaded nanoparticles; Single cell; Spheroids.
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