Nanoparticle IL-33 Covalent Pericardial Patch Inhibits Pseudoaneurysm Formation after Aortic Patch Angioplasty

<b>Background</b>: Pseudoaneurysm is a complication of interventional surgery and other vascular injuries; the formation mechanism is unclear. The purpose of this study was to explore the mechanism of IL-33 in pseudoaneurysms and develop a pericardial patch coated with IL-33 PLGA nanoparticles to inhibit pseudoaneurysm formation <b>Methods</b>: Rats were sacrificed on day 30 to observe the formation of pseudoaneurysms in NP-IL-33, NP-TGFβ-coated, and control groups. Histological staining was used to evaluate the size and breakage of the elastic fibers. Immunofluorescence was used to assess proliferation, macrophage infiltration, and TGF-β pathway activity. NP-SB431542 and LPS hydrogel were initially applied to assess the effect of the TGF-β inhibitor on IL-33 and the effect of IL-33 on macrophage infiltration. <b>Results</b>: NP-TGF-β (<i>p</i> = 0.0041) and NP-IL-33 (<i>p</i> = 0.0246) coated pericardial patches can inhibit the formation of pseudoaneurysms. The release of IL-33 can increase the expression of TGF-β (<i>p</i> = 0.0009), reduce the infiltration of M1 macrophages (<i>p</i> = 0.0009), and save the formation of pseudoaneurysms caused by the TGF-β inhibitor SB431542. <b>Conclusions</b>: IL-33 reduced the formation and progression of pseudoaneurysms by enhancing TGF-β pathway activity. A pericardial patch coated with IL-33 PLGA nanoparticles can reduce pseudoaneurysm formation after patch angioplasty, which has potential for clinical application.