title: Delivery of Liposomes with Different Sizes to Mice Brain after Sonication by Focused Ultrasound in the Presence of Microbubbles.
abstract: Imaging or therapeutic agents larger than the blood-brain barrier's (BBB) exclusion threshold of 400 Da could be delivered locally, non-invasively and reversibly by focused ultrasound (FUS) with circulating microbubbles. The size of agents is an important factor to the delivery outcome using this method. Liposomes are important drug carriers with controllable sizes in a range of nanometers. However, discrepancies among deliveries of intact liposomes with different sizes, especially those larger than 50 nm, across the BBB opened by FUS with microbubbles remain unexplored. In the present study, rhodamine-labeled long-circulating pegylated liposomes with diameters of 55 nm, 120 nm and 200 nm were delivered to mice brains after BBB disruption by pulsed FUS with microbubbles. Four groups of peak rarefactional pressure and microbubble dosages were used: 0.53 MPa with 0.1 μL/g (group 1), 0.53 MPa with 0.5 μL/g (group 2), 0.64 MPa with 0.1 μL/g (group 3) and 0.64 MPa with 0.5 μL/g (group 4). The delivery outcome was observed using fluorescence imaging of brain sections. It was found that the delivery of 55-nm liposomes showed higher success rates than 120-nm or 200-nm liposomes from groups 1-3. The result indicated that it may be more difficult to deliver larger liposomes (>120 nm) passively than 55-nm liposomes after BBB opening by FUS with microbubbles. The relative fluorescence area of 55-nm liposomes to the total area of the sonicated region was statistically larger than that of the 120-nm or 200-nm liposomes. Increasing peak rarefactional pressure amplitude or microbubble dose could induce more accumulation of liposomes in the brain using FUS with microbubbles. Moreover, the distribution pattern of delivered liposomes was heterogeneous and characterized by separated fluorescence spots with cloud-like periphery surrounding a bright center, indicating confined diffusion in the extracellular matrix after extravasation from the microvasculature. These findings are expected to provide useful information for developing FUS with microbubbles as an effective trans-BBB liposomal drug delivery strategy.
authors.affiliation: School of Biomedical Engineering, Shenzhen University, Shenzhen, Guangdong Province, P. R. China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, Guangdong Province, P. R. China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, Guangdong Province, P. R. China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Shen
authors.affiliation: School of Biomedical Engineering, Shenzhen University, Shenzhen, Guangdong Province, P. R. China.
authors.forename: Jinxuan
authors.initials: J
authors.lastname: Guo
authors.affiliation: School of Biomedical Engineering, Shenzhen University, Shenzhen, Guangdong Province, P. R. China.
authors.forename: Gaoshu
authors.initials: G
authors.lastname: Chen
authors.affiliation: School of Biomedical Engineering, Shenzhen University, Shenzhen, Guangdong Province, P. R. China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, Guangdong Province, P. R. China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, Guangdong Province, P. R. China.
authors.forename: Chien Ting
authors.initials: CT
authors.lastname: Chin
authors.affiliation: School of Biomedical Engineering, Shenzhen University, Shenzhen, Guangdong Province, P. R. China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, Guangdong Province, P. R. China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, Guangdong Province, P. R. China.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: School of Pharmacy, Shanghai Jiao Tong University, Shanghai, P. R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Physiology and Neurobiology, Xinxiang Medical University, Xinxiang, Henan Province, P. R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: Nanshan District Key Lab for Biopolymers and Safety Evaluation, College of Materials Science and Engineering, Shenzhen University, Shenzhen, Guangdong Province, P. R. China.
authors.forename: Shiguo
authors.initials: S
authors.lastname: Chen
authors.affiliation: School of Biomedical Engineering, Shenzhen University, Shenzhen, Guangdong Province, P. R. China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, Guangdong Province, P. R. China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, Guangdong Province, P. R. China. Electronic address: danguo@szu.edu.cn.
authors.forename: Guo
authors.initials: G
authors.lastname: Dan
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism*; D002199:Capillary Permeability; D016503:Drug Delivery Systems / Q000379:methods*; D005260:Female; D008081:Liposomes / Q000008:administration & dosage*; D051379:Mice; D008807:Mice, Inbred BALB C; D045423:Microbubbles; D023421:Models, Animal; D000069453:Ultrasonic Waves
chemical_list: D008081:Liposomes
keywords: Blood–brain barrier; Delivery; Different size; Focused ultrasound; Liposomes; Microbubbles