Abstrakt

Introduction: Boron neutron capture therapy (BNCT) is a targeted radiotherapy that represents a promising treatment for glioblastoma multiforme. BNCT efficacy depends on selective boron carriers capable of crossing the blood–brain barrier (BBB). Therefore, we propose an original strategy for boron delivery in BNCT, based on the cellular carriers. This study assessed the ability of bone marrow-derived macrophages (BMDMs) to accumulate boron carbide (B4C) nanoparticles, transport them across an in vitro BBB model toward glioblastoma cell-conditioned medium, and interact with tumor cells. Methods: The uptake and accumulation of B4C nanoparticles by BMDMs in different polarization states (M0, M1, M2) were confirmed by holotomography and ICP-MS. The scratch assay assessed spontaneous migration of BMDMs loaded with B4C nanoparticles. The Transwell system was used to determine the ability of BMDMs with B4C to cross bEnd.3 brain endothelial cell monolayer, mimicking the BBB, toward GL-261 glioblastoma cell-conditioned medium rich in CCL2. Macrophage interactions with glioblastoma spheroids were investigated using the CellTiter-Glo 3D Cell Viability Assay and flow cytometry. Results: All BMDM populations demonstrated the ability to accumulate B4C nanoparticles, with the significantly highest boron concentration detected in M1 macrophages (21.53 ± 1.64 mg/L per 106 cells). Moreover, M0, M1, and M2 macrophages loaded with B4C nanoparticles were capable of migrating through the brain endothelial cell monolayer, toward the glioblastoma cell-conditioned medium. BMDMs with nanoparticles did not affect the viability of glioblastoma spheroids after 6 days of co-culture, in contrast to macrophages without nanoparticles, which increased the survival of tumor cells. Importantly, CD206 expression was not increased in M1 macrophages after contact with spheroids, and was lower in M2 macrophages loaded with B4C nanoparticles compared to control M2 macrophages. Conclusion: BMDMs are promising carriers of B4C nanoparticles for BNCT due to their ability to cross the in vitro BBB model toward the glioblastoma microenvironment. The infographic illustrates the process involving bone marrow-derived macrophages (BMDMs). It begins with the preparation of BMDMs from C57BL/6 mice, isolating bone marrow cells from femur and tibia and differentiating them into M0, M1 and M2 macrophages. These BMDMs are then incubated with boron carbide nanoparticles. The next step shows the co-culture of BMDMs with glioblastoma spheroids. The analysis of boron carbide effects on BMDMs includes flow cytometry for BMDM markers, MTT viability assay, visualization of uptake using holography and boron concentration analysis by ICP-MS. The migration ability of BMDMs loaded with boron carbide is assessed through a scratch assay and a Transwell assay, showing migration across a blood-brain barrier model. Finally, BMDM and spheroid interactions are analyzed using a CellTiter-Glo 3D cell viability assay, CCL2 production via ELISA assay and flow cytometry for BMDM markers.BMDMs prep, boron carbide incubation, migration and glioblastoma spheroid interaction infographic.