First Metabolomic Signature of Blood-Brain Barrier Opening Induced by Microbubble-Assisted Ultrasound

Abstract

Microbubble (MB)-assisted ultrasound (US) is a promising physical method to increase non-invasively, transiently, and precisely the permeability of the blood-brain barrier (BBB) to therapeutic molecules. Previous preclinical studies established the innocuity of this procedure using complementary analytical strategies including transcriptomics, histology, brain imaging, and behavioral tests. This cross-sectional study using rats aimed to investigate the metabolic processes following acoustically-mediated BBB opening in vivo using multimodal and multimatrices metabolomics approaches. After intravenous injection of MBs, the right striata were exposed to 1-MHz sinusoidal US waves at 0.6 MPa peak negative pressure with a burst length of 10 ms, for 30 s. Then, the striata, cerebrospinal fluid (CSF), blood serum, and urine were collected during sacrifice in three experimental groups at 3 h, 2 days, and 1 week after BBB opening (BBBO) and were compared to a control group where no US was applied. A well-established analytical workflow using nuclear magnetic resonance spectrometry and non-targeted and targeted high-performance liquid chromatography coupled to mass spectrometry were performed on biological tissues and fluids. In our experimental conditions, a reversible BBBO was observed in the striatum without physical damage or a change in rodent weight and behavior. Cerebral, peri-cerebral, and peripheral metabolomes displayed specific and sequential metabolic kinetics. The blood serum metabolome was more impacted in terms of the number of perturbated metabolisms than in the CSF, the striatum, and the urine. In addition, perturbations of arginine and arginine-related metabolisms were detected in all matrices after BBBO, suggesting activation of vasomotor processes and bioenergetic supply. The exploration of the tryptophan metabolism revealed a transient vascular inflammation and a perturbation of serotoninergic neurotransmission in the striatum. For the first time, we characterized the metabolic signature following the acoustically-mediated BBBO within the striatum and its surrounding biological compartments.

Sonoporation of the Round Window Membrane on a Sheep Model: A Safety Study

“…The ultrasound parameters used were chosen given their effectiveness in delivering therapeutic molecules in various contexts. For example, these parameters have been used to increase the permeability of the blood-brain barrier [ 45 ] or to increase the extravasation of local drug delivery to tumor tissue [ 48 ], as well as in previous studies regarding sonoporation of the RWM [ 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Some previous studies demonstrated increased steroid delivery to the inner ear using 1-MHz ultrasound waves [ 28 ] and increased safety (according to histology) with 3 rather than 5 one-minute consecutive exposures for the RWM [ 30 ].…”

“…As previously described [ 45 ], Vevo MicroMarker ® MBs (VisualSonics—Fujifilm, Amsterdam, the Netherlands) are composed of a mixture of nitrogen and perfluorobutane gases encapsulated in a thin and flexible monolayer of phospholipids. MBs were prepared according to the manufacturer’s instructions (with 1 min of hand stirring and 10 min of resting at room temperature) and then diluted 10 times to reach a concentration of 2 × 10 8 MB/mL.…”

Engineered EVs designed to target diseases of the CNS

“…3b ). Another effort to non-invasively deliver drugs across the BBB is the use of intravascular microbubbles combined with focused ultrasound which disrupts the vasculature [ 141 , 142 ] ( Fig. 3c ), which could potentially be applied to EV administration.…”

“…(b) Intravascular microbubbles combined with focused ultrasound could potentially be applied to delivery of EVs into the CNS [ 140 ]. (c) EVs from various sources, including plants, milk and bacteria conjugated with microRNA molecules and administered orally were detected in mouse brain [ 141 , 142 ]. (d) Intravenous injection of EVs has the potential to deliver EVs to the brain but is limited due to limited biodistribution time and high clearance in peripheral organs [ 143 ] (e) Intraperitoneal injection showed high cell uptake of EVs at the local injection site [ 143 ] (f) Subcutaneous injection resulted in the lowest uptake of EVs by brain cells [ 129 ].…”