AAV-mediated TIMP-1 overexpression prevents aortic aneurysm progression in a murine model of Marfan syndrome

Background Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder caused by mutations affecting elastic fiber integrity and leading to progressive thoracic aortic aneurysm formation. Despite current pharmacological and surgical strategies, affected individuals remain at high risk of life-threatening aortic complications at a young age. Dysregulated extracellular matrix (ECM) remodeling, characterized by increased matrix metalloproteinase (MMP) activity and an imbalance between MMPs and their endogenous tissue inhibitors (TIMPs), is considered a central mechanism driving structural destabilization of the aortic wall in MFS. We therefore investigated whether targeted overexpression of TIMP-1 via adeno-associated virus (AAV)-mediated gene transfer could restore vascular integrity in a murine model of MFS. Methods and Results Marfan mice received systemic administration of G2CNN-tagged AAV9 vectors to achieve vascular transduction, encoding either TIMP-1 or EGFP as control. Four weeks after injection, transthoracic echocardiography was performed to assess aortic root diameter. Thoracic aortae were harvested for molecular and histological analyses, including gelatin zymography to quantify MMP activity, elastin staining to evaluate elastic fiber integrity, and assessment of tight junction protein expression in the intimal layer. AAV-mediated TIMP-1 overexpression resulted in a pronounced reduction of MMP activity compared to controls. Histological analyses demonstrated significantly preserved elastin architecture and reduced fragmentation of elastic fibers in treated animals. Moreover, echocardiographic measurements revealed a significant attenuation of aortic dilatation in TIMP-1–treated mice, indicating improved structural stability of the aortic wall. Conclusion AAV9-mediated overexpression of TIMP-1 effectively restores extracellular matrix balance, preserves elastin fiber architecture, and reduces aneurysm progression in a murine model of MFS. These findings support AAV-based TIMP-1 gene therapy as a promising disease-modifying strategy and warrant further translational evaluation as a novel therapeutic approach for patients with MFS.