title: Multi-modality safety assessment of blood-brain barrier opening using focused ultrasound and definity microbubbles: a short-term study.
abstract: As a potentially viable method of brain drug delivery, the safety profile of blood-brain barrier (BBB) opening using focused ultrasound (FUS) and ultrasound contrast agents (UCA) needs to be established. In this study, we provide a short-term (30-min or 5-h survival) histological assessment of murine brains undergoing FUS-induced BBB opening. Forty-nine mice were intravenously injected with Definity microbubbles (0.05 microL/kg) and sonicated under the following parameters: frequency of 1.525 MHz, pulse length of 20 ms, pulse repetition frequency of 10 Hz, peak rarefactional acoustic pressures of 0.15-0.98 MPa and two 30-s sonication intervals with an intermittent 30-s delay. The BBB opening threshold was found to be 0.15-0.3 MPa based on fluorescence and magnetic resonance imaging of systemically injected tracers. Analysis of three histological measures in hematoxylin and eosin-stained sections revealed the safest acoustic pressure to be within the range of 0.3-0.46 MPa in all examined time periods post sonication. Across different pressure amplitudes, only the samples 30 min post opening showed significant difference (p < 0.05) in the average number of distinct damaged sites, microvacuolated sites, dark neurons and sites with extravasated erythrocytes. Enhanced fluorescence around severed microvessels was also noted and found to be associated with the largest tissue effects, whereas mildly diffuse BBB opening with uniform fluorescence in the parenchyma was associated with no or mild tissue injury. Region-specific areas of the sonicated brain (thalamus, hippocampal fissure, dentate gyrus and CA3 area of hippocampus) exhibited variation in fluorescence intensity based on the position, orientation and size of affected vessels. The results of this short-term histological analysis demonstrated the feasibility of a safe FUS-UCA-induced BBB opening under a specific set of sonication parameters and provided new insights on the mechanism of BBB opening.
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, NY, USA.
authors.forename: Babak
authors.initials: B
authors.lastname: Baseri
authors.forename: James J
authors.initials: JJ
authors.lastname: Choi
authors.forename: Yao-Sheng
authors.initials: YS
authors.lastname: Tung
authors.forename: Elisa E
authors.initials: EE
authors.lastname: Konofagou
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000000981:diagnostic imaging*; D016503:Drug Delivery Systems / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D045423:Microbubbles; D011849:Radioactive Tracers; D012449:Safety; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D011849:Radioactive Tracers
references.citation: J Neurooncol. 2003 Oct;65(1):3-13
references.pmid: 14649881
references.citation: Ultrasound Med Biol. 2002 Mar;28(3):389-400
references.pmid: 11978420
references.citation: Cell Mol Neurobiol. 2000 Apr;20(2):231-53
references.pmid: 10696512
references.citation: J Neurocytol. 1995 Oct;24(10):795-806
references.pmid: 8586999
references.citation: Neuroimage. 2005 Jan 1;24(1):12-20
references.pmid: 15588592
references.citation: Neurosurgery. 1998 May;42(5):1083-99; discussion 1099-100
references.pmid: 9588554
references.citation: J Neurol Sci. 1998 Apr 1;156(2):119-32
references.pmid: 9588846
references.citation: Nat Rev Neurosci. 2006 Jan;7(1):41-53
references.pmid: 16371949
references.citation: Int J Cancer. 2007 Aug 15;121(4):901-7
references.pmid: 17437269
references.citation: Proc Natl Acad Sci U S A. 1994 Mar 15;91(6):2076-80
references.pmid: 8134351
references.citation: Neuron. 2002 Nov 14;36(4):555-8
references.pmid: 12441045
references.citation: PLoS One. 2008 May 14;3(5):e2175
references.pmid: 18478109
references.citation: Exp Neurol. 1960 Aug;2:379-405
references.pmid: 13807188
references.citation: Ultrasound Med Biol. 2003 Sep;29(9):1359-65
references.pmid: 14553814
references.citation: J Neurotrauma. 1997 May;14(5):313-26
references.pmid: 9199397
references.citation: J Membr Biol. 1998 Oct 1;165(3):201-11
references.pmid: 9767674
references.citation: Biochem Biophys Res Commun. 2006 Feb 24;340(4):1085-90
references.pmid: 16403441
references.citation: IEEE Trans Biomed Eng. 2010 Jan;57(1):145-54
references.pmid: 19846365
references.citation: Proc Natl Acad Sci U S A. 2006 Aug 1;103(31):11719-23
references.pmid: 16868082
references.citation: J Exp Med. 1956 Sep 1;104(3):337-60
references.pmid: 13357689
references.citation: J Drug Target. 1996;3(6):417-25
references.pmid: 8863135
references.citation: Clin Neurosci. 1997;4(4):179-83
references.pmid: 9186039
references.citation: Neuron. 2008 Jan 24;57(2):178-201
references.pmid: 18215617
references.citation: Ultrasound Med Biol. 2008 Dec;34(12):2028-34
references.pmid: 18692294
references.citation: Ultrason Imaging. 2008 Jul;30(3):189-200
references.pmid: 19149463
references.citation: Ultrasound Med Biol. 2010 May;36(5):840-52
references.pmid: 20420973
references.citation: J Neurosurg. 2006 Sep;105(3):445-54
references.pmid: 16961141
references.citation: Adv Drug Deliv Rev. 2008 Jun 30;60(10):1209-17
references.pmid: 18486271
references.citation: Neurol Med Chir (Tokyo). 1998 Jan;38(1):1-11
references.pmid: 9540326
references.citation: Ultrasound Med Biol. 2004 Jul;30(7):979-89
references.pmid: 15313330
references.citation: NeuroRx. 2005 Jan;2(1):3-14
references.pmid: 15717053
references.citation: Phys Med Biol. 2006 Feb 21;51(4):793-807
references.pmid: 16467579
references.citation: Radiology. 2001 Sep;220(3):640-6
references.pmid: 11526261
references.citation: Ultrasound Med Biol. 2005 Nov;31(11):1527-37
references.pmid: 16286030
references.citation: J Neurochem. 1997 Jul;69(1):232-45
references.pmid: 9202315
references.citation: Phys Med Biol. 2007 Sep 21;52(18):5509-30
references.pmid: 17804879
references.citation: Biomed Pharmacother. 1998;52(6):264-9
references.pmid: 9755826
references.citation: Histochemistry. 1978 Jun 9;56(2):97-115
references.pmid: 97249
references.citation: Ultrasound Med Biol. 2008 Jul;34(7):1093-104
references.pmid: 18378064
references.citation: Ultrasound Med Biol. 2007 Apr;33(4):584-90
references.pmid: 17337109
references.citation: Ultrasound Med Biol. 2010 Jan;36(1):58-67
references.pmid: 19900750
references.citation: Ultrasound Med Biol. 2007 Jan;33(1):95-104
references.pmid: 17189051
references.citation: Ultrasound Med Biol. 2007 Sep;33(9):1421-7
references.pmid: 17561334
references.citation: Ultrasound Med Biol. 2008 Jun;34(6):930-7
references.pmid: 18294757
references.citation: AMA Arch Neurol Psychiatry. 1956 Nov;76(5):457-67
references.pmid: 13371961