Numerical simulation study on opening blood-brain barrier by ultrasonic cavitation

Area of Science:

• Biomedical Engineering
• Acoustic Physics
• Pharmacology

Background:

• Experimental studies demonstrate ultrasonic cavitation's potential for reversible blood-brain barrier (BBB) opening to enhance drug delivery.
• Existing research primarily focuses on the experimental aspects of BBB opening, with less emphasis on the underlying physical mechanisms.

Purpose of the Study:

• To develop a computational model simulating the dynamic behavior of multiple microbubbles within blood vessels under ultrasonic cavitation.
• To elucidate the physical mechanisms governing drug molecule transport through endothelial cells during ultrasound-induced BBB opening.
• To identify key parameters influencing drug permeation and optimize conditions for enhanced drug delivery.

Main Methods:

• Development of a three-bubble-liquid-solid model to simulate microbubble dynamics in blood vessels.
• Analysis of bubble-bubble interactions, including the effect of large bubbles on small bubble movement.
• Investigation of microbubble vibration morphology influenced by acoustic parameters, bubble size, and inter-bubble distance.
• Modeling the generation of microjets and shock waves and their impact on vascular wall stress and permeability.

Main Results:

• Large bubbles were found to significantly inhibit the movement of smaller bubbles.
• Microbubble vibration morphology is dependent on acoustic parameters, bubble size, and spacing.
• Ultrasonic cavitation enhanced unidirectional drug molecule flux, with rates exceeding 5%.
• Microjets and shock waves alter vascular wall pore size and drug permeability.

Conclusions:

• Optimizing microbubble size, concentration, arrangement, and acoustic parameters can enhance drug permeation through the BBB.
• The developed model provides insights into factors affecting ultrasound-mediated BBB opening.
• This approach offers a potential method for actively regulating drug penetration across the neurovascular system's endothelial layer.