Paula Guerrero‐López

Glucose and oxygen availability are fundamental drivers of tumor progression, deeply influencing cancer cell proliferation, metabolism, and spatial organization. In this study, we present a simplified microfluidic-based 3D model of tumorigenesis that allows for controlled and dynamic analysis of key tumor parameters under metabolic stress. Using this platform, lung adenocarcinoma (A549) spheroids embedded in a collagen-based extracellular matrix were monitored over time to assess growth kinetics, hypoxic response via HIF-1α expression, and structural organization. A multifactorial experimental design combining variations in glucose, glutamine, and oxygen availability revealed distinct and specific effects of each nutrient. Glutamine deprivation led to widespread cell death, while glucose limitation strongly arrests cell proliferation. Finally, oxygen restriction disrupted spheroid architecture, resulting in loss of the proliferative outer capsule and the formation of internal cavities. Our approach provides a flexible system to study how microenvironmental cues shape tumor behavior, offering insights into metabolic vulnerabilities and the morphofunctional consequences of nutrient stress in cancer. Graphical Abstract Effect of glucose and oxygen depletion over spheroid growth and structural organization in a microfluidic device for 3D cell culture.

The importance of studying the ultrastructure is underwritten by decades of research. Ultrastructural features help to understand pathological processes or inform disease diagnosis. However, ultrastructural studies in the promising cancer‐on‐a‐chip models are practically nonexistent because of the complexity of sample preparation for electron microscopy techniques, which is particularly aggravated with these miniaturized models. Our aim was to study ultrastructural features of microphysiological systems (MPS) of the tumor microenvironment consisting of 3D multicellular tumor structures that were grown in hydrogel‐based cancer‐on‐a‐chip models. To this end, we selected two different MPS from our lab as examples and devised a sample preparation technique for their observation under dual‐beam focused ion beam scanning electron microscopy (FIB‐SEM) and transmission electron microscopy (TEM). The proposed methodology allowed high‐resolution visualization of both external and internal organization of 3D multicellular tumor structures, including cell–matrix interactions, cell–cell junctions, spheroid–spheroid contacts, matrix deposition, and extracellular vesicle‐mediated intercellular communication. This study demonstrates the feasibility of using advanced electron microscopy techniques to observe ultrastructural features of miniaturized cancer models, thus revealing a new dimension in the use of these models to study tumor processes and find new therapeutic targets.

Copper is a key trace element with established cytotoxic properties, yet its interactions with the extracellular matrix and their implications for the evolution of 3D culture models remain poorly understood. Here, we study how copper entrapped in collagen can regulate the structural and invasive properties of 3D tumor spheroids. Our findings reveal that copper influences cytoskeletal organization, protrusion dynamics, and epithelial–mesenchymal transitions. Interestingly, we also highlight its dual capacity to either suppress or enhance invasive behavior depending on the context of exposure. These results position copper as a context‐dependent modulator of tumor progression and underscore the importance of dose and timing in determining therapeutic outcomes. By integrating a physiologically relevant 3D model, this study provides new insights into copper–ECM interactions and identifies potential strategies to exploit them for cancer therapy.

The online version contains supplementary material available at 10.1186/s40170-025-00413-2. The online version contains supplementary material available at 10.1186/s40170-025-00413-2.

Beyond their classical role as cytotoxics, Platinum (Pt) coordination complexes recently joined the selected group of transition metals capable of performing bioorthogonal reactions in living environments. To minimize their reactivity towards nucleophiles, which limit their catalytic performance, we investigated the use of Pt(0) with different forms, sizes and surface functionalization. We report herein the development of PEGylated Pt nanodendrites with the capacity to activate prodyes and prodrugs in cell culture and in vivo. Their dendritic morphology together with their surface shielding through Pt−S‐bonded PEGylation synergistically contributed to create catalytic nanoreactors compatible with the highly‐crowded and reductive environment of the cell cytoplasm, thereby facilitating in situ bioorthogonal drug uncaging in cancer cells in 2D and 3D culture, including in microfluidic systems, and xenografted in zebrafish.

Beyond their classical role as cytotoxics, Platinum (Pt) coordination complexes recently joined the selected group of transition metals capable of performing bioorthogonal reactions in living environments. To minimize their reactivity towards nucleophiles, which limit their catalytic performance, we investigated the use of Pt(0) with different forms, sizes and surface functionalization. We report herein the development of PEGylated Pt nanodendrites with the capacity to activate prodyes and prodrugs in cell culture and in vivo. Their dendritic morphology together with their surface shielding through Pt−S‐bonded PEGylation synergistically contributed to create catalytic nanoreactors compatible with the highly‐crowded and reductive environment of the cell cytoplasm, thereby facilitating in situ bioorthogonal drug uncaging in cancer cells in 2D and 3D culture, including in microfluidic systems, and xenografted in zebrafish.

Cancer is a leading cause of death worldwide. Glioblastoma (GBM) is a major challenge in oncology due to its highly invasive nature and limited treatment options. GBM's aggressive migration beyond tumor margins and rapid tumor growth hinders success in patient treatment. Localized therapeutic delivery, such as the use of transition metals like copper, is highlighted as a novel therapeutic agent for many potential biomedical applications. Herein, it is aimed to study the effects of Cu release on the proliferation and invasiveness of cancer cells. To this end, novel copper‐based nanostructures with different release patterns are designed. Using a complex 3D cell culture model to mimic the tumor microenvironment, it is shown that different patterns of copper ion release have a strong impact on GBM progression and invasiveness. The findings highlight the importance of optimizing localized copper release patterns to tailor different tumor treatment strategies. They also show the potential and suitability of 3D microchips as instruments to study the behavior of tumor spheroids. In spite of their limitations, these 3D microdevices enable a controlled and close monitoring of the influence of environmental factors (such as the presence of Cu ions) on the proliferation and invasiveness of the cells, with a better approach to reality compared to 2D models and with a more controlled environment, compared to an in vivo model.