Comparative Study Of Pathological Feature And Ultrastructure Of Human Cerebral Gliomas Post-radiosurgery And Stereotactic Radiotherapy

ObjectiveTo study the radiobiological mechanism of radiotherapy on brain gliomas via observation of the histopathological change and ultrastracture features of human gliomas treated with stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT). And we also collect data to explore the new therapeutics for the integrated management of gliomas.MethodsA comparative, retrospective study of pathological change and immunohistochemistry of 25 glioma specimens without radiotherapy and 25 cases with SRS and SRT, and the ultrastructure of 8 glioma specimens without radiotherapy and 8 with SRS and SRT, were carried out. All the specimens were taken from their tumor center, tumor margin and peripheral edema brain tissues in each case. And the findings were statistically analyzed as to get an objective assessment.Results1. Traditional pathological observation1) Control groupAccording to the multiformity of tumor cells, the nuclear fission, the density of tumor cells, vascular endothelial proliferation and the extent of tumor necrosis, gliomas are divided into LGG and HGG group under optical microscope. The LGG is well differentiated, including subtypes of fibrillary, protoplasmic, gemistocytic and mixed astrocytoma. The HGG includes anaplastic astrocytoma and glioblastoma. The former was mainly expressed in significant increase of tumor cell density, nuclear atypia, deeply stained nuclear, mitotic nuclear, vascular endothelial cell proliferation. In glioblastoma, there was tumor cell congeries, obvious unclear atypia, different types of single-core or multi-core giant tumor cell as well as substantial necrosis and blooding. 2) Treatment groupSimilar radiation injury characteristics with different degrees were observed in all cases of the study. The structure of tumor cells at the tumor center disappeared. Whereas lots of cell fragments remained at the edge of the center areas. Some tumor cells died and hyperemia as well as hyaline degeneration could be seen. The structure of blood vessels looked like coats of onions. Swelled cells, enlarged cells, puffed endocylema and hyaline degeneration of the vessel wall can also be found. The walls of blood vessel were thickened and lumen narrowed. Some inflammatory cell infiltrated. Some small blood vessels around the brain tumor tissues dilated and became hyperemia.The square and extent of tumor necrosis and liquation were positively correlated with the tumor grade significantly (P<0.05).2. Electron microscopic observation1) Control group①Central tumor: In the tissue of LGG, tumor cells were observed with uniform nuclear atypia, vascular endothelial cells evenly. There are great many organelles without edema. And vessel endothelial cell without edema yet with integrated basement membrane were also easy found. In the tissue of HGG, tumor cells with large, irregular, multiform nuclear, mild swelling of mitochondria in the cytoplasm and expansion in endoplasmic reticulum were observed. The normal appearance of capillaries exist, the tight junctions between endothelial cell are still closed, mitochondria and endoplasmic reticulum expansion, the thickness of basement membrane is uneven.②Tumor edge: The morphology of tumor cells is similar to that in tumor center. And there was no significant difference between vascular endothelial cells in tumor edge and in tumor center. Yet there were apertures or openings on colloidal membrane of vascular endothelial cells as well as the extra-membrane extravasate in the tumor edge.③Peripheral edema cortex: The tumor cells can also be observed. The capillary endothelial cells are not swelling. In cytoplasm small pinocytic vesicles, mitochondria and rough endoplasmic reticulum are existed, the thickness of basement membrane is even and integrity.2) Treatment group①Central tumor: The tumor necrosis could be found in the center of all the specimen tissues. It was revealed as follows: the cellular membrane was incomplete or disappeared, chondriosomes of astrocytes swelled, cristae decreased or disappeard, and expansion of endoplasmic reticulum was vacuolated. In cellular nucleus, the chromatin was concentrated, autosomel was reduced or disappeared, and even some cellular nucleus were disrupted and dissolved. Some of vascular endothelial cells were disrupted and shedding. The structure of vessel wall was disappeared. The basement membrane was ruptured and a larger number of hemorrhagic foci were appeared. And the apoptosis cells could be found in some tissues. ②Tumor edge: The appearances of tumor cells in tumor edge were similar with that in the central field, yet more tumor cells were shown completed. The swelling organelle was the primary features. The cellular membrane was incomplete or disappeared. The chondriosomes, golgiosome of astrocytes were swelled obviously and expansion of endoplasmic reticulum was often vacuolated. The cellular nucleus was irregular and appeared serrate depression. The pseudo inclusion bodies could be found. And heterochromatin was concentrated peripherally. Only a little of vacuoles appeared in the peripheral enchylema in some specimens. Their cellular nucleus was revealed completely with the increased nucleus gap. And the apoptosis cells could also be found in some tissues.③Peripheral edema cortex: Some tumor cells could be found in most cases. But they varied much less in appearance. We could find some of the neuron cells were swelling, heterochromatin were increased and collected. The nucleus margin was abnormal, the nucleus gap was increased, and nucleolus could be revealed easily. And the lipofuscin was also increased. The hondriosomes of astrocytes were swelling, golgi apparatus, rough endoplasmic reticulum and glycogen granules reduced. The heterochromatin in glial cell nucleus was increased. There were single or multiple vacuoles also. And some of myelin was demyelinated.3. Immunohistochemistry examination1) Control group: The expression of Ki-67, VEGF protein and the MVD in HGG group were significant higher than those in LGG. And they were positively correlated with the glioma grade. And the Ki-67 protein expression was positively correlated with the VEGF protein expression and the MVD. Yet the VEGF protein expression was not significantly correlated with the MVD.2) Treatment group: The expression of Ki-67, VEGF protein and the MVD in HGG group were significant higher than those in LGG. And they were positively correlated with the glioma grade. And the Ki-67 protein expression was positively correlated with the VEGF protein expression and the MVD. The VEGF protein expression was also positively correlated with the MVD.3) Deference between the gliomas with and without SRS/SRT: The Ki-67 protein expression and the MVD in treatment group were significant lower than those of the control group in both LGG and HGG. Yet there was no significant difference of expression of VEGF between treatment group and control group.ConclusionThe radiotherapy plays an important role in the suppression and destruction of the glioma cells directly. Both degeneration and necrosis of glioma cells were found in the pathological and ultrastracture observation. The radiation efficacy not only depends on the intensity of radiation, the time of fraction, the way of irradiation, but also on the tumor grade and the proliferation phase in the cell cycle.Radiotherapy can also induce apoptosis. How to promote or induce tumor apoptosis is great important in clinical application which would improve the long-term outcome of gliomas.Microvascular endothelial cells have high sensitivity to SRS and SRT. After irradiation, the endothelial cells underwent swelling, loss, compensatory proliferation and increasing of fibrous stroma was observed. The fibrous thickening of the vascular walls was observed, following with marked lymphocyte infiltration and hemorrhages. The radiation injury of microvascular endothelial cells is one of the major radiotherapeutic radiobiological mechanisms of SRS and SRT.Ionizing radiation induced the destruction of ultrastructure in blood-brain barrier and increased permeability. It provided a theoretical basis to the comprehensive treatment of radiotherapy combined chemotherapy and biotherapy.Stubborn brain radiation necrosis and brain edema is the common result of the necrosis of tumor cells, the injury of glial cells, angiohyalinosis, the destroied blood-brain barrier and the myelin of different cellular necrosis.Seeking for personalized unique therapeutics for different glioma patients is promoted up to date.①To promote substitute traditional radiotherapy for SRT.②The extended-field conformal radiotherapy combined with SRS or hypofractionated SRT are recommended for the malignant gliomas.③The combination therapy of radiotherapy and chemotherapy are also promoted for the malignant gliomas.④The VEGF targeted therapy is also recommended with the combination of radiotherapy and chemotherapy.⑤The high single dose SRS and hypofractionated SRT are suitable for both postoperative residual LGG and recurrent LGG.⑥The primary undiagnosed cerebral tumors with mass effects are feasible for direct operation as to get the diagnosis and decompression.