Pitt Shield

Targeted delivery of antibodies through the blood-brain barrier by MRI-guided focused ultrasound.

Authors: Kinoshita M, McDannold N, Jolesz FA, Hynynen K

The blood-brain barrier (BBB) is a persistent obstacle for the local delivery of macromolecular therapeutic agents to the central nervous system (CNS). Many drugs that show potential for treating CNS diseases cannot cross the BBB and there is a need for a non-invasive targeted drug delivery method that allows local therapy of the CNS using larger molecules. We developed a non-invasive technique that allows the image-guided delivery of antibody across the BBB into the murine CNS. Here, we demonstrate that subsequent to MRI-targeted focused ultrasound induced disruption of BBB, intravenously administered dopamine D(4) receptor-targeting antibody crossed the BBB and recognized its antigens. Using MRI, we were able to monitor the extent of BBB disruption. This novel technology should be useful in delivering macromolecular therapeutic or diagnostic agents to the CNS for the treatment of various CNS disorders.

Introduction

Purpose drug delivery with BBB opening
Study Objective To demonstrate the image-guided, site-specific delivery of a macromolecular antibody across the BBB into the mouse CNS using MRI-guided focused ultrasound.
Animal model / Human subject 15 Swiss- Webster mice (10 weeks), weighing 30–35 g
Disease model healthy
MRI or image guidance method Yes (MRI)
Targeted brain region(s) Gray Matter
Cargo name and characteristics rabbit anti-human dopamine D4 receptor antibody
Route of administration intravenously

Outcomes and Safety

Summary of Outcomes MRI-guided focused ultrasound could successfully, locally, and reversibly open the blood‑brain barrier, allowing intravenously administered antibodies to be delivered specifically into the mouse brain (hippocampus and basal ganglia) and bind to their target antigens (dopamine D₄ receptors). Furthermore, changes in MRI signal were well correlated with the extent of antibody delivery, indicating that MRI can be used to monitor and predict the effectiveness of the procedure.
Safety-related matter At acoustic pressures of 0.6-0.8 MPa, BBB opening was achieved with no or minimal hemorrhage. Pressures ≥ 0.9 MPa caused increased incidence of severe tissue damage (hemorrhage). Optimal pressure for safe BBB disruption was 0.6-0.8 MPa.

Brain Region

Ultrasound Parameters

Ultrasound instrument home assembled (in-house manufactured) focused, piezoelectric transducer with 100mm diameter, and 80mm radius of curvature
FUS Frequency 0.69Hz
FUS Pressure 0.6, 0.8, 0.9, 1.1MPa
FUS Mode pulsed
Pulse duration 10ms
Duration of a single FUS session 40s
Focal Characteristics Focal spot diameter: 2.3 mm Focal length: 14 mm
Treatment frequency single session

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