背景:超声和光声(US/PA)成像是用于体内可视化和评估药物递送的有前途的工具。然而,颅骨的声学特性限制了US/PA成像在大脑中的实际应用。为了应对靶向药物递送到大脑和经颅US/PA成像的挑战,我们介绍并评估了基于激光激活的全氟化碳纳米液滴(PFCnDs)的脑内递送和成像策略.
方法:开发了两种专门的PFCnD,以促进血脑屏障(BBB)的开放和对比增强的US/PA成像。在老鼠身上,PFCnD通过PFCnD诱导的BBB向大脑右侧开放而被递送至脑组织。在体内,我们进行了经颅US/PA成像,以评估PFCnDs用于颅骨造影增强成像的实用性.离体,采用体积US/PA成像来表征进入脑组织的PFCnDs的空间分布.进行免疫组织化学分析以确认BBB开口的空间范围和成像结果的准确性。
结果:体内,经颅US/PA成像显示与递送的PFCnD相关的局部光声(PA)对比.此外,超声造影(CEUS)成像证实同一区域内存在纳米液滴.离体,体积US/PA成像显示,PA对比位于PFCnD诱导的BBB开放的脑区.免疫组织化学分析显示,免疫球蛋白(IgG)外渗到大脑中的空间分布与成像结果紧密匹配。
结论:使用我们的脑内输送和成像策略,PFCnDs被成功传送到大脑的目标区域,并且他们能够通过颅骨进行对比增强US/PA成像。离体成像,和免疫组织化学证实了该方法的准确性和精确性。
BACKGROUND: Ultrasound and photoacoustic (US/PA) imaging is a promising tool for in vivo visualization and assessment of drug delivery. However, the acoustic properties of the skull limit the practical application of US/PA imaging in the brain. To address the challenges in targeted drug delivery to the brain and transcranial US/PA imaging, we introduce and evaluate an intracerebral delivery and imaging strategy based on the use of laser-activated perfluorocarbon nanodroplets (PFCnDs).
METHODS: Two specialized PFCnDs were developed to facilitate blood‒brain barrier (BBB) opening and contrast-enhanced US/PA imaging. In mice, PFCnDs were delivered to brain tissue via PFCnD-induced BBB opening to the right side of the brain. In vivo, transcranial US/PA imaging was performed to evaluate the utility of PFCnDs for contrast-enhanced imaging through the skull. Ex vivo, volumetric US/PA imaging was used to characterize the spatial distribution of PFCnDs that entered brain tissue. Immunohistochemical analysis was performed to confirm the spatial extent of BBB opening and the accuracy of the imaging results.
RESULTS: In vivo, transcranial US/PA imaging revealed localized photoacoustic (PA) contrast associated with delivered PFCnDs. In addition, contrast-enhanced ultrasound (CEUS) imaging confirmed the presence of nanodroplets within the same area. Ex vivo, volumetric US/PA imaging revealed PA contrast localized to the area of the brain where PFCnD-induced BBB opening had been performed. Immunohistochemical analysis revealed that the spatial distribution of immunoglobulin (IgG) extravasation into the brain closely matched the imaging results.
CONCLUSIONS: Using our intracerebral delivery and imaging strategy, PFCnDs were successfully delivered to a targeted area of the brain, and they enabled contrast-enhanced US/PA imaging through the skull. Ex vivo imaging, and immunohistochemistry confirmed the accuracy and precision of the approach.