DID YOU KNOW?
MICROBUBBLES CAN AID VASCULAR DEMENTIA BY DELIVERING A DRUG TO LARGE BLOOD VESSELS NEAR THE HEART [H.11]
WHAT ARE MICROBUBBLES?
Microbubbles are microscopic bubbles filled with gas, its purpose used to aid in ultrasound images and drug delivery. These agents are between 3 μm diameter wide are surrounded by shell composed of lipids, polymers, and proteins. Enchantment of the ultrasound image occurs as the microbubbles resonate in the ultrasound beams, contracting according to changes in pressure of sound waves. Microbubbles could additionally be used to deliver drugs, aiding in targeting tumors involved in cancer. Embolotherapy is a specific technique used to restrict blood flow to blood vessels, thus ceasing tissue growth and has included using acoustic droplet vaporization. Acoustic droplet vaporization involves the use of microbubbles to perform drug deliveries. For more on these techniques CLICK HERE.
VOYAGE OF MICROBUBBLES
When microbubbles are discharged into the bloodstream, they circulate throughout the body. The exterior lipid layer is absorbed by the liver while the interior gas is passed through by the lungs. Additionally, microbubbles dissolve into the bloodstream within 20-30 minutes.
WHERE DO MICROBUBBLES CIRCULATE?
1. Administered with an IV injection
3 cups
Blueberries
4. Liver absorbs the outer layer of the microbubble
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Butter
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Flour
2.. Follows circulation to the right heart
3. Proceeds with circulation to the lungs
5. Large enough micro bubbles will become restricted in the small space and dissolve
Click on the image to have a visualization where microbubbles circulate. Additionally, microbubbles are lined with ligands which allow for a clearer and accurate targeting of biomarkers. Microbubbles bind to the targeted area, some examples including inflammation, tumors, ischemic memory which occurs when the brain does not receive a sufficient amount of blood supply and can lead to memory loss, or reperfusion injuries. As a result, the ability to locate the diseased area is enriched with the ultrasound and can be administered by EMTs with an IV injection during an ambulance ride. Techniques such as the flexible tether space arm and folds in the microbubble also aid in achieving a clearer image.
ADVANTAGES: THE BRAIN
Diseases involving the brain are more meticulous due to the blood brain barrier (BBB). According to Burgess and Hynynen, "the blood-brain barrier (BBB) which prevents access of ∼98% of current pharmaceutical agents to the brain when delivered intravenously." Microbubbles and a focused ultrasound in conjunction have the ability to cause an increase in permeability in the (BBB), allowing for a greater chance of drug delivery. Acoustic cavitation occurs as microbubbles expand and shrink to cause the widening of blood vessels, allowing for the disruption of the barrier for drug therapy. However, the endothelial cell wall might become damaged in the process. More research has been conducted, focusing on vascular dementia which may occur when blood vessels rupture in the brain. Kathleen Morgan and Tyrone Porter are developing a synthetic prototype drug that is transported to blood vessels near the heart by microbubbles. The aorta becomes stiffer as one progresses with age, inducing the possibility that blood can reach the blood vessels in the brain and rupture. The development of a new peptide to revert the stiffness of the aorta has the ability to prevent microbleeds in the future. For more about advantages revolving around microbubbles CLICK HERE.
Click to listen for a quick lecture about the fundamentals of microbubbles.
ADVANTAGES WITH CONTRAST ULTRASOUNDS
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Contrast ultrasounds are deemed more harmless opposed to radionuclide imaging due to lack of radiation
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Ultrasounds have the ability to view blood flow in real time imaging
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Compared to other imaging devices like PET, MRI, and SPECT scans which average around thousands of dollars, ultrasounds are more cost friendly, ranging from $200-$300
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For a microbubble to target a different area, a ligand can be easily attached to the surface to change its course of direction
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Micrograms of microbubbles are needed to conduct ultrasounds compared to large amounts of substances needed for MRI scans due to their ability to induce strong signals
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Contrast ultrasounds can depict the amount of blood flow and passageway of fluids through the circulatory system
