gms | German Medical Science

Malignant gliomas are common brain tumors with a bad prognosis despite intense therapeutic effort. They typically present a markedly increased angiogenesis, which is dependent on tumor grade. In order to target tumor angiogenesis efficiently, the basics of glioma vascularisation have to be evaluated. Therefore, the use of organotypic endothelial cells (EC) as well as tumor derived EC is mandatory.

Microvascular ECs were isolated and cultured from healthy brain tissue and from gliomas WHO grade I-IV by modification of the method of Bowman et al. (1982). Fresh tissue from the operation room was freed from large vessels and then minced and digested enzymatically, followed by percoll gradient centrifugation. EC were then separated using magnetic beads linked to UEAI, CD105-, CD31-, E-selectin- and VE-cadherin antibodies. Positive cells were seeded into culture flasks coated with gelatine. Cells were characterized immunohistochemically by the EC specific markers vWF, GLUT 1 and by their uptake of DiI-Ac-LDL. Proliferation was quantified by the MTT test. MMP expression was analyzed by PCR. As a functional assay we used the tube formation assay on Matrigel.

EC morphology did not correlate with tumor grade. EC from high grade gliomas showed significantly higher proliferation rates than ECs from low grade gliomas and ECs from healthy brain tissue. Only EC from high grade gliomas expressed MMP-7 and MMP-9 on RNA level. No difference was observed in expression of MMP 2 and 3.

A reproducible method for the isolation of EC from brain tumors could be established successfully. First data indicate “malignant” properties of ECs isolated from high grade gliomas. Whether these processes are tumor-specific or generally found in activated ECs, e.g. during wound healing, is still to be proven.