PhD Scientific Days 2024

Poster Session E - Molecular Medicine 2.

Atomic force microscopy investigation of human fibrillin microfibril morphology and mechanics in Marfan syndrome

Text of the abstract

Introduction: Fibrillin microfibrils are architectural extracellular matrix components that maintain structural integrity and regulate signaling events in the connective tissue. Mutations in the gene for fibrillin-1 result in Marfan syndrome (MFS), an autosomal dominant connective tissue disorder leading to cardiovascular, ocular, and skeletal abnormalities. Life expectancy is affected in this population due to aortic involvement, which results from a disrupted vascular extracellular matrix.
Aims: To perform a nanoscale morphological and mechanical characterization of fibrillin microfibrils harboring mutations in the fibrillin-1 gene compared to unaffected homologous microfibrillar assemblies.
Methods: Human aortic wall samples were obtained from patients undergoing specific cardiovascular surgical interventions. Fibrillin microfibrils were extracted by bacterial collagenase digestion and purified by size-exclusion chromatography before being visualized and investigated with atomic force microscopy (AFM). Non-contact mode-derived height data was used for the detailed three-dimensional study of microfibrillar morphology, including bead height, length, width, and interbead region height. Microfibrillar stiffness was assessed using force curves recorded in fast force mapping mode.
Result: The obtained fibrillin microfibrils displayed the characteristic “beads-on-a-string” appearance, with a consistent mean periodicity of 50-60 nm. MFS fibrillin-1 microfibrils displayed an altered bead morphology with significantly thinner (19.05 vs. 22.44 nm, p<0.0001) and shorter (17.69 vs. 20.55 nm, p<0.0001) beads. AFM-based indentation revealed a core and a cortex region for the beads, which displayed different elastic properties. Young’s moduli in the core region were significantly larger in the MFS group (11.56 vs. 9.32 MPa, p<0.0001).
Conclusion: MFS fibrillin-1 microfibrils exhibited an altered structure which was reflected in bead morphology (mainly length and width). MFS beads were stiffer. The data provide insight into the morphological and elastic properties of fibrillin microfibrils, revealing differences that may be indicative of the structural role of microfibrillar assemblies in the development of Marfan syndrome-specific aortic symptomatology.
Funding: ÚNKP-23-3-II-SE-22; SE 250+ Excellence PhD Scholarship; TKP2021-EGA-23; RRF-2.3.1-21-2022-00003.