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ObjectiveUltrasound (US) and ultrasound contrast agents (UCAs) provide a way to noninvasively induce targeted angiogenesis. However, there exists a lack of understanding regarding the mechanisms of this process that has impeded progress. This study sought to characterize the angiogenic response, by both exploring the role of UCA concentration ([UCA]) in bioeffect induction at 0 days post exposure (DPE) and assessing the bioeffect as a possible potentiator of angiogenesis at 5 DPE.
A 1-MHz ultrasonic transducer was used to expose the gracilis muscles of Sprague Dawley rats for 5 min with a 10-μs pulse duration, 10-Hz pulse repetition frequency, and 0.7-MPa peak rarefactional acoustic pressure (p r). Four [UCA]s were tested: 0x (saline), 1×, 5×, and 10×, where 1× is 5% Definity by volume of solution. Evans blue dye (EBD) was used to quantify changes in acute vascular permeability (0 DPE), and VEGF expression was quantified at 5 DPE to support that angiogenesis had occurred. CD31 staining was used to assess capillary density at both time points.
[UCA] was a significant parameter for determining EBD leakage (permeability) and VEGF expression ( p < 0.001 for both). However, [UCA] was not a significant parameter for capillary density at 0 or 5 DPE. Multiple comparisons between 0 and 5 DPE showed that only 10× [UCA] at 5 DPE was significantly different than 0 DPE, suggesting a [UCA] dependence of the angiogenic response.
ConclusionsThis study suggests that [UCA] was a significant parameter in the induction of an angiogenic response with US and UCAs. It also suggests that rather than damage from US and UCAs, as previously speculated, a nondestructive mechanical interaction between the UCAs and vascular endothelium induces bioeffects to potentiate the angiogenic response.
How to Cite
JOHNSON, Chenara A; O’BRIEN, William D. The angiogenic response is dependent on ultrasound contrast agent concentration. Vascular Cell, [S.l.], v. 4, n. 1, p. 10, may 2012. ISSN 2045-824X. Available at: <https://vascularcell.com/index.php/vc/article/view/10.1186-2045-824X-4-10>. Date accessed: 20 jan. 2022. doi: http://dx.doi.org/10.1186/2045-824X-4-10.