Blood Brain Barrier

The brain is precious, and evolution has gone to considerable lengths to safeguard it. Your 7mm thick skull is the most apparent portion of your body, but the brain is also surrounded by protective fluid (cerebrospinal - of the brain and spine) and a protective membrane known as the meninges. Both provide additional protection against physical injury. The blood-brain barrier is another layer of defence. This, as the name implies, is a barrier between the blood arteries (capillaries) of the brain and the cells and other components that comprise brain tissue. The blood-brain barrier shields the brain from disease-causing viruses and poisons found in human blood, whereas the skull, meninges, and cerebrospinal fluid shield the brain from physical harm.

When Paul Ehrlich, a German physician, inserted a dye into the circulation of a mouse, he discovered the blood-brain barrier. Surprisingly, all tissues except the brain and spinal cord were penetrated by the dye. While this established the presence of a barrier between the brain and blood, it wasn't until the 1960s that scientists were able to use powerful enough microscopes to identify the physical layer of the blood-brain barrier.

The "endothelial tight junction" is now known to be the primary component of the blood-brain barrier that provides a barrier. Endothelial cells line all blood vessels. Endothelial cells are jammed extraordinarily close to one other in the capillaries that constitute the blood-brain barrier, generating so-called tight junctions. Only tiny molecules, fat-soluble compounds, and some gases can move readily past the capillary wall and into brain tissue due to the narrow gap. Some larger molecules, like as glucose, can enter via transporter proteins, which operate as special doors that only open for specific molecules. Other components of the blood-brain barrier surround the endothelial cells of the blood artery and are not directly engaged in preventing items from passing from blood to brain, but rather communicate with the cells that make up the barrier to modify how selective it is.

Scientists demonstrated in an Alzheimer's disease animal model that employing ultrasound to open the blood-brain barrier can improve cognition and reduce the amount of harmful plaque that accumulates in the brain. They believe this is due to ultrasound's ability, in conjunction with injected gas microbubbles, to breach the blood-brain barrier momentarily and safely, allowing protective blood-borne factors to enter. Importantly, this method did not cause brain injury.

Scientist discovered in a new study that by temporarily opening the blood-brain barrier, ultrasound allows more therapeutic antibodies into the brain, improving Alzheimer's-like pathology and cognition more than either ultrasound or antibody medicine alone.

As a result, ultrasound is a promising method for temporarily and safely bypassing the generally extremely beneficial, but occasionally troublesome, blood-brain barrier. It can be utilised to increase drug delivery to the brain, making treatments for Alzheimer's and other brain illnesses more cost-effective.

Why do We Need it?

The blood-brain barrier's purpose is to protect the brain from circulating toxins or pathogens that could cause infections while enabling important nutrients to reach the brain. It also helps to maintain relatively regular quantities of hormones, nutrients, and water in the brain, which might upset the finely regulated environment.

So, What Happens If the Blood-brain Barrier is Damaged or Somehow Compromised?

One typical cause is bacterial infection, such as in meningococcal illness. Meningococcal bacteria can attach to the endothelium wall and cause tight junctions to open slightly. As a result, the blood-brain barrier weakens, allowing bacteria and other poisons to enter brain tissue, causing inflammation and, in extreme circumstances, death. Other conditions are thought to compromise blood-brain barrier function. In multiple sclerosis, a defective blood-brain barrier, for example, allows white blood cells to penetrate the brain and target the functions that transport instructions from one brain cell (neuron) to another. This has an impact on how neurons communicate with one another.

When do We Need to Get Through it?

The blood-brain barrier is normally quite successful in preventing harmful chemicals from entering the brain, however there is a drawback to this. The great majority of possible medication treatments fail to penetrate the barrier, posing a significant challenge to treating mental and neurological illnesses. One possibility is to "trick" the blood-brain barrier into enabling the medicine to pass through. Using the Trojan horse procedure, the drug is attached to a molecule that can cross the blood-brain barrier via a transporter protein.