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Drug delivery Crossing the barrier
The blood-brain barrier protects against invasion by blood-borne pathogens in an effort to safeguard the microenvironment that sustains complex neural function. But what happens when a neurological disease alters that function? Sarah Harris speaks to Vera Neves, senior staff researcher at the University of Lisbon, and Stacy Blain, chief science officer of Concarlo Therapeutics and professor at SUNY Downstate Medical Center, about the role of ‘peptide shuttles’ in overcoming this barrier and what research in this area could potentially lead to.
he blood-brain barrier plays a vital role in ensuring that the network of cells that surrounds the blood vessels in the brain maintain function by limiting the entry of harmful substances, such as toxins, pathogens and large molecules – all while still allowing the necessary nutrients to pass through. In practical terms, this means the vast majority of blood vessels in the brain have a different structure to those found in other areas of the body. The endothelial cells that line every blood vessel are fused together to form tight junctions that prevent entry to the aforementioned invaders.
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Embedded around the surface of the blood vessel in what’s known as the basal lamina are chemical detector cells called pericytes, which pick up on anything in the bloodstream that shouldn’t be there and contract to prevent entry so that nearby macrophages can dispose of it. The final element is the end-feet of astrocytes – specialised glial cells that supply nutrients from blood vessels to neurons – which wrap around the entire blood vessel and control the defensive functions of the other cells mentioned. Despite the crucial function the barrier provides, it also prevents the delivery of the majority of drugs to the brain.
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World Pharmaceutical Frontiers /
www.worldpharmaceuticals.net
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