Endothelial cells of brain microvessels limit the entry into the brain for
xenobiotics and many drugs, which otherwise may be therapeutically active in the
central nervous system. The ABC transporters, P-glycoprotein and Breast cancer
resistance protein, which are predominantly located in the luminal surface of capillary
endothelial cells, are key players for this barrier function. Thus, particular efforts have
been made to overcome the blood-brain barrier or to circumvent these efflux pumps.
The various options for drug transport into the brain include encapsulation of active
compounds into delivery systems, e.g. liposomes, which are able to by-pass the export
pumps and to convey their payload across the endothelial barrier. The applied systems
target receptors at the luminal surface of the blood-brain barrier by using antibodycoupled
immunoliposomes, liposomes conjugated to receptor-targeting vectors such as
insulin, transferrin and apolipoproteins or cationized albumin-coupled liposomes.
Keywords: Albumin, ApoE, Blood-brain barrier, Immunoliposomes, Insulin, Pglycoprotein,
Transferrin.
