Author: John Paul Ortiz Bustillo, Elette Engels, Elrick T. Inocencio, Michael Lerch, Julia Rebecca D Posadas, Anatoly Rosenfeld, Kiarn Roughley, Moeava Tehei, Gordon Wallace, Danielle Warren, Vincent de Rover 👨🔬
Affiliation: Centre for Medical Radiation Physics, University of Wollongong Australia, Department of Radiology, University of the Philippines- Philippine General Hospital, Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, AIIM Facility, University of Wollongong Australia, Centre for Medical Radiation Physics, University of Wollongong, Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, AIIM Facility, University of Wollongong, University of the Philippines Manila; Centre for Medical Radiation Physics, University of Wollongong Australia 🌍
Purpose: To compare the biological response through cell viability assay and fluorescence imaging of 3D bioprinted brain cancer (glioma) constructs relative to 2D monolayer and 3D spheroid culture for synchrotron microbeam radiation therapy (MRT) experiments
Methods: Encapsulated glioma constructs were prepared using gelatin methacryloyl (GelMA) hydrogel, and two glioma cell lines (9L rat gliosarcoma and a U87 human glioma). 2D monolayer and 3D spheroid cell cultures were prepared using the same cell lines. A 3D REDI bioprinter was used to print glioma tumor construct using optimized bioprinting parameters. A third-generation synchrotron light source was used to deliver both synchrotron broad-beam (SBB) and MRT beams with mean energy of 94.75 keV and doses of 5, 10, and 20 Gy. Furthermore, encapsulated glioma cells were incorporated inside 3D printed rat and adult head phantoms to mimic realistic scattering conditions. A WST-1 cell viability assay, and propidium iodide (PI) fluorescence imaging was done after treatment delivery.
Results: A peak-to-valley dose ratio (PVDR) of 50.8 +/- 2.5 and 10.0 +/- 0.8 were measured for the 3D printed rat and adult head phantoms, respectively. Synchrotron MRT killed more 9L and U87 glioma cells relative to SBB for all cancer models. Striated pattern of damaged cells was observed in the encapsulated gliomas using PI fluorescence imaging due to MRT beams. Encapsulated 9L cells inside a rat phantom show to have significant difference between SBB and MRT cell viability due to the measured high PVDR.
Conclusion: 3D bioprinting is an innovative technology in fabricating 3D cell models simulating a more realistic 3D cell environment. It has some different treatment response compared to 2D monolayer and 3D spheroid cultures. In addition, it can resolve the striated cell damage due to MRT delivery using fluorescence imaging. This study presents initial characterization of 3D bioprinting protocols for experimental radiotherapy.