New radiation modalities have made it possible to prolong the survival of individuals with malignant brain tumors, but symptomatic radiation necrosis becomes a serious problem that can negatively affect a patient's quality of life through severe and lifelong effects. Here we review the relevant literature and introduce our original concept of the pathophysiology of brain radiation necrosis following the treatment of brain, head, and neck tumors. Regarding the pathophysiology of radiation necrosis, we introduce two major hypotheses: glial cell damage or vascular damage. For the differential diagnosis of radiation necrosis and tumor recurrence, we focus on the role of positron emission tomography. Finally, in accord with our hypothesis regarding the pathophysiology, we describe the promising effects of the anti-vascular endothelial growth factor antibody bevacizumab on symptomatic radiation necrosis in the brain.

We evaluate the clinical results of a form of tumor selective particle radiation known as boron neutron capture therapy (BNCT) for newly-diagnosed gl

Occlusive cerebrovascular disease leads to brain ischemia that causes neurological deficits. Here we introduce a new strategy combining mesenchymal stromal cells (MSCs) and ex vivo hepatocyte growth factor (HGF) gene transferring with a multimutated herpes simplex virus type-1 vector in a rat transient middle cerebral artery occlusion (MCAO) model. Gene-transferred MSCs were intracerebrally transplanted into the rats' ischemic brains at 2 h (superacute) or 24 h (acute) after MCAO. Behavioral tests showed significant improvement of neurological deficits in the HGF-transferred MSCs (MSC-HGF)-treated group compared with the phosphate-buffered saline (PBS)-treated and MSCs-only-treated group. The significant difference of infarction areas on day 3 was detected only between the MSC-HGF group and the PBS group with the superacute treatment, but was detected among each group on day 14 with both transplantations. After the superacute transplantation, we detected abundant expression of HGF protein in the ischemic brain of the MSC-HGF group compared with others on day 1 after treatment, and it was maintained for at least 2 weeks. Furthermore, we determined that the increased expression of HGF was derived from the transferred HGF gene in gene-modified MSCs. The percentage of apoptosis-positive cells in the ischemic boundary zone (IBZ) was significantly decreased, while that of remaining neurons in the cortex of the IBZ was significantly increased in the MSC-HGF group compared with others. The present study shows that combined therapy is more therapeutically efficient than MSC cell therapy alone, and it may extend the therapeutic time window from superacute to acute phase.

Background and Purpose— Fibroblast growth factor-2 (FGF-2) administration and bone marrow stromal cell (MSC) transplantation could improve neurological deficits after occlusive cerebrovascular disease. In the present study, we examined the effects of neurological improvement after transient middle cerebral artery occlusion (MCAO) in rats by a novel therapeutic strategy with FGF-2 gene–transferred MSCs by the herpes simplex virus type 1 (HSV-1) vector. Methods— Adult Wistar rats were anesthetized. Nonmodified MSCs, FGF-2–modified MSCs with HSV-1 1764/-4/pR19/ssIL2-FGF-2, or PBS was administered intracerebrally 24 hours after transient right MCAO. All animals underwent behavioral tests for 21 days, and the infarction volume with 2-3-5-triphenylterazolium was detected 3 days and 14 days after the MCAO. Three days and 7 days after the MCAO, the FGF-2 production in the ipsilateral hemisphere of the MCAO was measured with ELISA. Seven and 14 days after the MCAO, immunohistochemical staining for FGF-2 was applied. Results— The stroke animals receiving FGF-2–modified MSCs demonstrated significant functional recovery compared with the other groups. Fourteen days after the MCAO, there was a significant reduction in infarction volume only in FGF-2–modified MSC-treated group. FGF-2 production in the FGF-2–modified MSC-treated brain was significantly higher compared with the other groups at 3 and 7 days after MCAO. Administrated FGF-2–modified MSCs strongly expressed the FGF-2 protein, which was proven by ELISA. Conclusions— Our data suggest that the FGF-2 gene–modified MSCs with the HSV-1 vector can contribute to remarkable functional recovery after stroke compared with MSCs transplantation alone.