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Systemic delivery of targeted nanotherapeutic reverses angiotensin II-induced A.A.A

Systemic delivery of targeted nanotherapeutic reverses angiotensin II-induced abdominal aortic aneurysms in mice



Schematic representation of the study design.

Abdominal aortic aneurysm (AAA) disease causes dilation of the aorta, leading to aortic rupture and death if not treated early. It is the 14th leading cause of death in the U.S. and 10th leading cause of death in men over age 55, affecting thousands of patients. Despite the prevalence of AAA, no safe and efficient pharmacotherapies exist for patients. The deterioration of the elastic lamina in the aneurysmal wall is a consistent feature of AAAs, making it an ideal target for delivering drugs to the AAA site.


In this research, they conjugated nanoparticles with an elastin antibody that only targets degraded elastin while sparing healthy elastin. After induction of aneurysm by 4-week infusion of angiotensin II (Ang II), two biweekly intravenous injections of pentagalloyl glucose (PGG)-loaded nanoparticles conjugated with elastin antibody delivered the drug to the aneurysm site. They show that targeted delivery of PGG could reverse the aortic dilation, ameliorate the inflammation, restore the elastic lamina, and improve the mechanical properties of the aorta at the AAA site. Therefore, simple iv therapy of PGG loaded nanoparticles can be an effective treatment option for early to middle stage aneurysms to reverse disease progression and return the aorta to normal homeostasis.



(a) In-vivo targeting study using DiR loaded nanoparticles (DiR-NPs). DiR NPs were injected via tail vein and after 24 h animals were euthanized d to assess the targeting. The signal given by the DiR-NPs in the IVIS images (a2,a3) indicated that DiR-NPs only accumulate at the suprarenal aortic area where the aneurysm developed (a1), suggesting the successful targeting of the nanoparticles to the aneurysmal tissue; (b) VVG staining of the aneurysmal tissue showing elastin damage and (c) fluorescent image of the same site showing distribution of the DiR-NPs (purple) within the tissue, indicating that DiR-NPs target the degraded elastin (green autofluorescence) in the aneurysm.


Abdominal aortic aneurysms (AAAs) are characterized by chronic transmural inflammation, resulting in the breakdown of extracellular matrix proteins such as elastin and collagen in the aortic wall, and this plays a vital role in AAA pathophysiology. Mounting evidence has suggested that elastin, one of the key components of the extracellular matrix (ECM), drives progression of this disease by virtue of its degradation by matrix metalloproteinases (MMPs) at the disease site.



In vivo ultrasound and dilation change.

(a) Representative B-mode in vivo ultrasound images of abdominal aortas before pump implantation, at 4 weeks when the infusion of Ang II was finished and treatment started, and 8 weeks when the animals were euthanized; (b) Gross view of representative aortas from BLN-NPs (b1), PGG-NPs (b2) and control groups (b3) at 8 week; (c) Dilation percentage of BLN-NPs group, PGG-NPs group and control group. After therapy PGG-NPs group showed progressive reversal of aneurysmal dilation while control and BLN-NPs groups showed continuous increase in aneurysms. *Indicate timepoint that have dilation percentage significantly different from week 4 (p < 0.1); bars indicate significant difference between groups (p < 0.05).



AAAs, due to their asymptomatic nature, are only detected during general screening; surgical intervention is only recommended when the diameter of the aorta grows to 5.5 cm or larger, as the risk outweighs benefits below those levels in these patients. No pharmacotherapy is available for those patients who are diagnosed with small AAA. Some small AAAs do rupture and cause death; therefore, pharmacotherapy to prevent AAA's further growth is needed. An ideal therapeutic intervention would prevent further ECM degradation and restore structural integrity and cellular homeostasis, leading to reversing the disease. Their group has successfully demonstrated the beneficial effects of pentagalloyl glucose (PGG) in stabilizing and regenerating vascular ECM both in vitro and in vivo.


Circumferential strains (CS) and pulse wave velocity (PWV).

(a) Representative M-mode in-vivo ultrasound images of abdominal aortas before pump implantation, at 4 weeks after infusion of Ang II, and at 8 weeks at the end of therapy, showing the mechanical behavior change within a cardiac cycle for PGG-NPs, BLN-NPs and control groups; (b) Percent change of corresponding circumferential Green–Lagrange strains throughout the cardiac cycle at weeks 2 and 4, and during the treatment at weeks 5, 6, 7 and 8. All aneurysmal aortas showed a reduction in CS after formation of the aneurysms. After treatments, PGG-NPs group showed a progressive increase of the CS while the CS of the BLN-NPs group and control group kept decreasing; (c) Corresponding PWV at weeks 2 and 4, and during the treatment at weeks 5, 6, 7 and 8. All aneurysmal aortas showed a reduction in the PWV after formation of the aneurysms at 4 week. After treatments, PGG-NPs group showed an increase of the pulse wave velocity, while the pulse wave velocity of the BLN-NPs group and the control group kept decreasing due to further aortic dilation. * indicate timepoint that have dilation percentage significantly different from week 4 (p < 0.05); bars indicate significant difference between groups (p < 0.05).


While no single animal model captures AAA disease comprehensively, the angiotensin II infusion model shows the spontaneous development of AAAs with very similar pathophysiology to human AAA. Here they present a successful treatment of AAAs in the Ang II model using targeted nanoparticle delivery.



Histological analysis.

(a,b) H&E staining for aneurysms; BLN-NPs, control and PGG-NPs groups are at lower (a1–4) and higher (b1–4) magnifications, showing the morphology and the cell infiltration of the suprarenal aortic tissue. The PGG-NPs group had better morphology and minimal cell infiltration compared to the other groups (the opening shown in a4 and d4 was a vessel branching out from the aorta); (c,d) VVG staining for aneurysms; BLN-NPs, control and PGG-NPs groups are at lower (c1–4) and higher (d1–4) magnifications, showing the elastin damage within the tissue. The elastic laminae in the PGG-NPs were repaired as compared to before therapy while in other groups they continued to degrade.


They show that PGG-loaded bovine serum albumin (BSA) nanoparticles can be targeted to damaged elastin in aneurysmal mouse aorta. Delivered PGG not only protects elastin from MMP-mediated degradation but also regenerates lost elastic lamellae. PGG delivery also triggered anti-inflammatory signals locally and systemically. Using inflation-extension testing, they further demonstrate the efficacy of the treatment in restoring aortic mechanical properties1.



Local inflammatory response analysis of aneurysmal tissues.

(a,b) IHC results for CD68 (a1-a4), staining for pan macrophage infiltration, and CD80 (b1-b4), staining for M1 macrophages, in the suprarenal aneurysmal aortic tissue from 4-week group (before therapy), and at 8-wks for control, BLN-NPs, and PGG-NPs groups. PGG therapy reduced macrophage infiltration in the AAA sites; (c) In-situ zymography showing MMP gelatinolytic activity in aneurysmal tissue from 4-week group (before therapy), and at 8-wks control, BLN-NPs and PGG-NPs groups; (d) qPCR results of mRNA extracted from aneurysms harvested for MMP-2, TIMP-1 and TIMP-2 expression showing reduction of MMP-2 (*p < 0.05) and increase in TIMP-1 and -2 in PGG group.



Systemic inflammatory response analysis.

(a) Serum IFN-γ concentrations of control, BLN-NPs and PGG-NPs groups. PGG-NPs-treated group showed significantly lower serum IFN- γ level than both control and BLN-NPs groups; (b) Flow cytometry dot plots and scatter plot for CD 68 positive cells in spleen and thymus from control and PGG-NPs-treated group. The percentage of CD 68 positive cells significantly decreased in spleen in PGG-NPs-treated group in comparison to control group. These results indicate the PGG-NPs therapy decreases systemic inflammatory response. *p < 0.03, **p < 0.05. ***p < 0.01.

  1. Wang, X., Parasaram, V., Dhital, S. et al. Systemic delivery of targeted nanotherapeutic reverses angiotensin II-induced abdominal aortic aneurysms in mice. Sci Rep11, 8584 (2021). https://doi.org/10.1038/s41598-021-88017-w