PhD Discussion. Ona Baguer and Dario Castellana
Dual-Action 3D Biomaterial for radiotherapy: protection and regeneration of tissue during X-ray treatment
Radiotherapy and ablative surgery are the standard of care for patients with head and neck squamous cell carcinoma. Radiation-based therapy can trigger side effects due to the ionizing beam, which impair the patient’s quality of life. Amifostine is the only FDA-approved ROS-scavenging radioprotective drug, but its clinical application is limited by suboptimal therapeutic effects under standard systemic delivery. We propose the application of a local delivery system to improve and extend the therapeutic window of the drug. A GelMA-based hydrogel embedding amifostine-loaded PLGA nanoparticles and calcium/zinc ionic nanoparticles can simultaneously protect the irradiated tissue and support the regeneration of resected areas. The radioprotective drug, Amifostine, was encapsulated in spherical PLGA nanoparticles (~250 nm) using a double-emulsion synthesis protocol. This approach generated amifostine nanoparticles (AMF NPs) achieving an encapsulation efficacy above 90%, the nanoparticles were further embedded in a GelMA hydrogel, controlling and tuning the drug release kinetics. To trigger and support the regeneration of new tissue, a bottom-up protocol was developed to synthesize calcium- and zinc-based ionic nanoparticles (iNPs). The obtained iNPs were used to functionalize the surface of the GelMA hydrogel to promote a fast release of biological ions with angiogenic effects in the ablated tissue. The final delivery system was obtained upon crosslinking of a GelMA precursor solution enriched with amifostine-loaded PLGA NPs, followed by surface modification with iNPs. The system can therefore sustain the fast release of iNPs from its surface and a controlled release of AMF-NPs from its matrix. In conclusion, the proposed biomaterial will have a dual therapeutic effect: the rapid release of amifostine can reduce ROS concentration in the irradiated area, while the sustained release of bioactive ions supports tissue regeneration and vascularization over time.
Nuclear mechanics regulates the epithelial-mesenchymal transition in pancreatic cancer cells
Ona Baguer, Cellular and Molecular Mechanobiology
The progression of pancreatic ductal adenocarcinoma (PDAC) is associated with the emergence of populations of cancer cells exhibiting both epithelial and mesenchymal features, a state known as partial epithelial–mesenchymal transition (EMT). The EMT phenotypes are regulated by biochemical and mechanical cues from the tumour microenvironment, including TGF-β signalling, stromal stiffening and spatial constraints, which can converge on shared signalling pathways. However, how they interact to shape distinct EMT phenotypes remains poorly understood. To address this question, we developed an in vitro system in which all three cues could be independently controlled: spatial constraints by micropatterning cells into circular colonies, substrate stiffness by culturing colonies on gels with tunable stiffness, and TGF-β signalling by adding TGF-β1 to the culture medium. Using a PDAC cell line with a weakly epithelial phenotype, we analysed EMT markers alongside local mechanical features at the single-cell level and identified local cell density as a key regulator of EMT. Specifically, local cell density regulated the expression of epithelial junctional markers and modulated TGF-β1-induced mesenchymal marker expression. In contrast, substrate stiffness primarily promoted cell spreading and migration, increasing the extent of low-density regions and thereby reshaping the spatial distribution of EMT phenotypes. These spatial differences were accompanied by changes in nuclear morphology, pointing to a potential role for nuclear mechanics. Consistent with this, lamin A/C knockdown, which increases nuclear deformability, enhanced mesenchymal features even in the absence of exogenous TGF-β1. Together, these findings indicate that nuclear mechanics contributes to mediating the effects of mechanical and biochemical cues on EMT phenotypes, providing insights into how the tumour microenvironment modulates cell plasticity.
