Liebi, M. | bioRxiv Science

bioRxiv2023

Multiscale Multimodal Characterization and Simulation of Structural Alterations in Failed Bioprosthetic Heart Valves

Calcific degeneration is the most frequent type of heart valve failure, with rising incidence due to the ageing population. The gold standard treatment to date is valve replacement. Unfortunately, calcification oftentimes re-occurs in bioprosthetic substitutes, with the governing processes remaining poorly understood. Here, we present a multiscale, multimodal analysis of disturbances and extensive mineralisation of the collagen network in failed bioprosthetic bovine pericardium valve explants with full histoanatomical context. In addition to highly abundant mineralized collagen fibres and fibrils, calcified micron-sized particles previously discovered in native valves were also prevalent on the aortic as well as the ventricular surface of bioprosthetic valves. The two mineral types (fibers and particles) were detectable even in early-stage mineralisation, prior to any macroscopic calcification. Based on multiscale multimodal characterisation and high-fidelity simulations, we demonstrate that mineral occurrence coincides with regions exposed to high haemodynamic and biomechanical indicators. These insights obtained by multiscale analysis of failed bioprosthetic valves may serve as groundwork for the evidence-based development of more durable alternatives. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/529530v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@c7e0b5org.highwire.dtl.DTLVardef@71bdbdorg.highwire.dtl.DTLVardef@15fdc23org.highwire.dtl.DTLVardef@6dbd1c_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2020

3D nanoscale analysis of bone healing around degrading Mg implants studied by X-ray scattering tensor tomography

The nanostructural adaptation of bone is crucial for its compatibility with orthopedic implants. The bones nanostructure determines its mechanical properties, however little is known about its temporal and spatial adaptation in degrading implants. This study presents insights into this adaptation by applying electron microscopy, elemental analysis, and small-angle X-ray scattering tensor-tomography (SASTT). We extend the SASTT reconstruction to multiple radii of the reciprocal space vector q, providing a 3D reciprocal-space map per voxel. Each scattering curve is spatially linked to one voxel in the volume, and properties such as the thickness of the mineral particles are quantified. This reconstruction provides information on nanostructural adaptation during healing around a degrading ZX10 magnesium implant over the course of 18 months, using a sham as control. The nanostructural adaptation process is observed to start with an initially fast interfacial organization towards the implant direction, followed by a substantial reorganization of the volume around the implant, and an adaptation in the later degradation stages. The study sheds light on the complex bone-implant interaction in 3D, allowing a more guided approach towards the design of future implant materials, which are expected to be of great interest for further clinical studies on the bone-implant interaction. TOC text and figureDegrading Magnesium implants are mechanically and chemically well adapted orthopedic implant materials and ensure a gradual load transfer during bone healing due to their degradation. The impact of the implant degradation on the bone nanostructure is however not fully understood. This study unveils the processes 3D and shows different stages of bone healing. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=181 SRC="FIGDIR/small/375253v1_ufig1.gif" ALT="Figure 1"> View larger version (83K): org.highwire.dtl.DTLVardef@1a0ab0borg.highwire.dtl.DTLVardef@13d7486org.highwire.dtl.DTLVardef@1ad4485org.highwire.dtl.DTLVardef@6d9c86_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗