Cerebral microdialysis in glioma studies, from theory to application

• Microdialysis is a novel technique opening up new possibilities in glioma studies.
• Microdialysis allows directly sampling of interstitial fluid in tumor in vivo.
• Location of probe within glioma is important for properly assessing the PK data.
• High molecular weight cut-off catheters allow detecting larger molecules.
• Combination of microdialysis and other techniques evolve into a useful application.

Despite recent advances in the treatment of solid tumors, there are few effective treatments for malignant gliomas due to the infiltrative nature, and the protective shield of blood–brain barrier or blood–tumor barriers that restrict the passage of chemotherapy drugs into the brain. Imaging techniques, such as PET and MRI, have allowed the assessment of tumor function in vivo, but they are indirect measures of activity and do not easily allow continuous repeated evaluations. Because the biology of glioma on a cellular and molecular level is fairly unknown, especially in relation to various treatments, the development of novel therapeutic approaches to this devastating condition requires a strong need for a deeper understanding of the tumor's pathophysiology and biochemistry. Cerebral microdialysis, a probe-based sampling technique, allows a discrete volume of the brain to be sampled for neurochemical analysis of neurotransmitters, metabolites, biomarkers, and chemotherapy drugs, which has been employed in studying brain tumors, and is significant for improving the treatment of glioma. In this review, the current concepts of cerebral microdialysis for glioma are elucidated, with a special emphasis on its application to neurochemistry and pharmacokinetic studies.