Determining Ultrasound Parameters for Bursting Polymer Microbubbles for Future Use in Spinal Cord Injury

This study explores using ultrasound to burst tiny bubbles (microbubbles) made of a polymer called poly(lactic acid) (PLA) to deliver drugs to spinal cord injuries (SCI). The goal is to find the safest and most effective ultrasound settings to burst these bubbles and release their therapeutic cargo at the injury site. The researchers tested different ultrasound frequencies and pressures to see how well they could burst the PLA microbubbles both in a lab setting and in a rat cadaver model of SCI. They also investigated how to load the bubbles with a model drug (DNA) and release it upon bursting. The study found that PLA microbubbles can be successfully imaged and burst in a spinal cord injury model using clinical ultrasound. The optimal ultrasound settings for bursting the bubbles were identified, ensuring they are below levels that could cause further damage to the spinal cord.

• 1
  PLA microbubbles can be successfully imaged and burst in a spinal cord injury model using clinical ultrasound.
• 2
  Optimal ultrasound parameters for bursting were found to be near the resonance frequency of 2.5 to 3.0 MHz, with pressure thresholds between 0.2 and 0.5 MPa.
• 3
  The microbubbles, initially around 2 μm in size, collapsed to between 0.5 and 1 μm upon bursting but did not fragment into smaller pieces.