Nanocarrier drugs in the treatment of brain tumors

Nanoparticle-mediated targeted delivery of drugs might significantly reduce the dosage and optimize their release properties,increase specificity and bioavailability,improve shelf life,and reduce toxicity.Some nanodrugs are able to overcome the blood-brain barrier that is an obstacle to treatment of brain tumors.Vessels in tumors have abnormal architecture and are highly permeable;moreover,tumors also have poor lymphatic drainage,allowing for accumulation of macromolecules greater than approximately 40 kDa within the tumor microenvironment.Nanoparticles exploit this feature,known as the enhanced permeability and retention effect,to target solid tumors.Active targeting,i.e.surface modification of nanoparticles,is a way to decrease uptake in normal tissue and increase accumulation in a tumor,and it usually involves targeting surface membrane proteins that are upregulated in cancer cells.The targeting molecules are typically antibodies or their fragments;aptamers;oligopeptides or small molecules.There are currently several FDA-approved nanomedicines,but none approved for brain tumor therapy.This review,based both on the study of literature and on the authors own experimental work describes a comprehensive overview of preclinical and clinical research of nanodrugs in therapy of brain tumors.