TY - JOUR A1 - Hoenicka, Markus A1 - Kaspar, Marcel A1 - Schmid, Christof A1 - Liebold, Andreas A1 - Schrammel, Siegfried T1 - Contact-free monitoring of vessel graft stiffness - proof of concept as a tool for vascular tissue engineering T2 - Journal of tissue engineering and regenerative medicine N2 - Tissue-engineered vessel grafts have to mimic the biomechanical properties of native blood vessels. Manufacturing processes often condition grafts to adapt them to the target flow conditions. Graft stiffness is influenced by material properties and dimensions and determines graft compliance. This proof-of-concept study evaluated a contact-free method to monitor biomechanical properties without compromising sterility. Forced vibration response analysis was performed on human umbilical vein (HUV) segments mounted in a buffer-filled tubing system. A linear motor and a dynamic signal analyser were used to excite the fluid by white noise (0-200 Hz). Vein responses were read out by laser triangulation and analysed by fast Fourier transformation. Modal analysis was performed by monitoring multiple positions of the vessel surface. As an inverse model of graft stiffening during conditioning, HUV were digested proteolytically, and the course of natural frequencies (NFs) was monitored over 120 min. Human umbilical vein showed up to five modes with NFs in the range of 5-100 Hz. The first natural frequencies of HUV did not alter over time while incubated in buffer (p = 0.555), whereas both collagenase (-35%, p = 0.0061) and elastase (-45%, p < 0.001) treatments caused significant decreases of NF within 120 min. Decellularized HUV showed similar results, indicating that changes of the extracellular matrix were responsible for the observed shift in NF. Performing vibration response analysis on vessel grafts is feasible without compromising sterility or integrity of the samples. This technique allows direct measurement of stiffness as an important biomechanical property, obviating the need to monitor surrogate parameters. Copyright (C) 2016 John Wiley & Sons, Ltd. KW - ANEURYSMS KW - ARTERIES KW - Biomechanics KW - BIOREACTOR KW - BLOOD-VESSELS KW - BYPASS GRAFTS KW - CONSTRUCTS KW - design KW - extracellular matrix KW - human umbilical vein KW - IN-VITRO KW - MECHANICAL-PROPERTIES KW - proteolysis KW - small calibre graft KW - vascular tissue engineering Y1 - 2017 UR - https://opus4.kobv.de/opus4-oth-regensburg/frontdoor/index/index/docId/3105 VL - 11 IS - 10 SP - 2828 EP - 2835 PB - Wiley ER -