From visualization to mechanistic resolution: Methodological considerations for cell-mineral interactions in three-dimensional breast tumor models.

Cohen et al. (2026) introduced a three-dimensional multicellular breast tumor model containing hydroxyapatite (HA) and calcium oxalate dihydrate (COD) microcalcification analogs and used cryo-scanning electron microscopy (cryo-SEM), together with backscattered-electron imaging and energy-dispersive X-ray spectroscopy (EDS), to visualize mineral-biological interfaces. Their study provides valuable spatial information on crystal distribution, aggregation, and apparent intracellular and extracellular localization. However, several of the biological interpretations proposed from these observations would benefit from complementary evidence capable of distinguishing spatial association from mineralization mechanism. Here, we discuss five methodological issues: (i) the distinction between visualization and mechanistic inference; (ii) the interpretation of intracellular crystal localization; (iii) the need for orthogonal physicochemical characterization; (iv) the influence of the three-dimensional tumor microenvironment; and (v) the evidential chain connecting mineral properties to biological and clinical implications. We emphasize that these considerations do not diminish the value of cryo-SEM or the 3D model. Rather, they identify specific opportunities to combine spatial imaging with temporal, biochemical, physicochemical, and functional measurements. We further propose a minimum reporting framework for future studies of cell-mineral interactions in 3D tumor models, organized around four linked questions: where the mineral is located, what the mineral is, how it reaches or forms at that location, and whether its presence produces measurable biological consequences.