Development of an Experimental Platform for Gamma Knife Radiosurgery in Mouse Brains

The limited availability of post-Gamma Knife radiosurgery (GKRS) samples and the unsuitability of clinical GKRS devices for small animals highlight the need to develop devices that enable the application of a clinical GKRS device in mouse models. This study introduces a novel platform specifically designed for utilizing the Leksell Gamma Knife in mouse studies. The 3D-printed device comprises a positioning platform and a head fixation device. Six-week-old C57BL/6N mice underwent irradiation targeting the left caudate putamen (CPu) or left anterior frontobase areas. Clinical Gamma Knife prescription doses (central radiation doses of 80 Gy, 60 Gy, 50 Gy, 40 Gy, 20 Gy, and 10 Gy) were administered as single exposures. Dose conversion experiments confirmed that the actual radiation dose delivered to mice was consistently 1.5-fold higher than the planned clinical dose. MRI and H&E staining revealed clear radiation necrosis (RN) in the targeted areas when the planned clinical dose of 80 Gy was applied to the CPu and anterior frontobase, confirming the device's accuracy. γ-H2AX staining showed significant DNA double-strand breaks in the targeted region, particularly after a planned clinical dose of 40 Gy and higher. H&E staining also indicated parenchymal hemorrhage, tissue loss, and edema in the targeted areas among groups exposed to the planned clinical central doses of 80 Gy, 60 Gy, and 50 Gy. Immunofluorescence staining of CD68, IBA1, and NeuN showed significant neuroinflammation in the targeted areas of the high-dose groups (planned clinical doses of 80 Gy, 60 Gy, 50 Gy, or 40 Gy), characterized by increased microglia activation, macrophage infiltration, and neuronal death. This study developed a novel mouse platform for the Leksell Gamma Knife, enabling precise GKRS in mouse brains. For adult C57BL/6N mice, a planned clinical central dose of 40 Gy may be considered a suitable threshold for radiation-induced brain injury.