These deaths were mainly due to traumatic intracranial hemorrhage and/or brain edema after operation. To avoid these accidents, we took the following measures: 1) 22# trochar was replaced by 24# trochar; 2) transplantation volume was reduced to 2 mm3; and 3) the tumor tissues were pushed as smoothly as possible. Take rate is not the only criterion in evaluation of an orthotopic animal model, while how close a model can replicate the original tumors is more essential. As brain metastasis and primary glioblastioma are two biologically different malignances in the central

nervous system, we selected them both as grafts in this study to assess this novel method. When compared between the two models, metastasis 17DMAG nmr xenografts were evidently differentiated from glioblastoma xenograft in many aspects, however, when compared with their original malignances, both models demonstrated unquestionable similarity in histological structure features check details and growth patterns. Laurent et al. [10] performed both heterotransplantation www.selleckchem.com/products/ly333531.html and orthotopic transplantation of human glioblastoma, and concluded that the organ-specific environment play a determining role in growth and invasive properties. In the current study, two different malignances were transplanted into the same organ; however, the resulting tumors didn’t demonstrate the similar growth patterns. So, it is more

plausible and acceptable that it is the malignance itself but not environment that plays a determining role in the tumor growth patterns and other biological behaviors. With the identification of brain tumor stem cells from tumor mass or cell lines, it is reported that as rare as 102 CD133+ glioma cells could generate tumor mass, while as much as 106 CD133- glioma cells failed to form tumor mass after injected to the mouse brain. The fact that cell suspension injection of most established cell lines often yields well-circumscribed

intracranial tumors which are different from the original tumor, coupled with the complicated procedure of cell suspension injection precludes tumor stem cells as a desirable transplant [19–21]. In this study, the immunohistochemistry Alanine-glyoxylate transaminase with monoclone antibody against CD133 revealed that not only the original tumors, but the resulting tumors were positively stained for CD133. This result means the tumor tissues contained brain tumor stem cells and functioned as a tumor stem cell pool. It is reported that biological behaviors of tumor stem cells are highly dependent on their microenvironment [22, 23], in another word, CD133 negative tumor cells and stromal components also play an important role in the potential of tumor stem cells to re-establish the original tumor. Taken together, tumor stem cells, other tumor cells and stromal components make a concerted contribution to the growth of tumor mass in transplantation animal model.