CHAPTER 20: Cationic Polymers as Carriers through the Blood–Brain Barrier

The blood–brain barrier (BBB) is an organization lined with brain endothelial cells, bound by extracellular matrix and sealed with paracellular protein complexes that acts as a selective transport and metabolic boundary. The BBB is designed to regulate brain homeostasis and to allow selective transport of molecules that are essential for the proper functioning of the brain. The BBB is an internal defense system that acts as a block to the delivery of nucleic acids and drug molecules to the brain. This defines a challenge for an effective delivery of therapeutics to the central nervous system (CNS). A number of potential biomolecules have failed at their developmental stage for clinical use due to an unsuccessful delivery to the CNS in required amounts. In this perspective, an in-depth research has been undertaken to understand the mechanisms underlying the transportation across the BBB via carriers. Amongst the various strategies, the use of cationic polymer carriers for nucleic acid and drug delivery across the BBB has gained much attention. This chapter reviews the developments of different cationic polymers vectors for delivering genes and drugs across the BBB.