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Is tissue augmentation a reality in biosurgery? An experimental study of endothelial cell invasion into tissue filler
Tomaž Velnar, Vladimir Smrkolj, Marjan Rupnik, Lidija Gradišnik, 2013, original scientific article

Abstract: New therapeutic approaches for wound treatment are evolving. Non healing wounds in oncology and after trauma may be cured by a novel technique of tissue augmentation with soft tissue fillers. The principle resides in filling the wound with collagen filler in order to seal the defect and promote healing. Successful angiogenesis forms the basis of tissue filler survival and determines the outcome of the healing process. During this study, basic data about endothelial cell invasion into collagen-made substratum was collected that could be used for neoangiogenesis studies in tissue augmentation techniques for large wound defect treatment. In the in vitro assay, the human umbilical vein endothelial cells (HUVEC) grow into a three-dimensional framework of collagenous tissue fillers, forming the basic step for angiogenesis. After heparins were used as chemotactic agents, a typical bell-shaped relationship between chemotaxis and agent concentrations was found. Significant cell infiltration was present in the assays with chemotactic agents. These observations support the potential for tissue augmentation with soft tissue fillers that could be used in acute and chronic non healing traumatic and oncology wounds after extensive surgical resections and radiotherapy.
Keywords: angiogenesis, cell invasion, tissue augmentation, tissue filler, wound healing
Published in DKUM: 10.07.2015; Views: 1535; Downloads: 105
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Evaluation of thermal and mechanical filler gas influence on honeycomb structures behaviour
Matej Vesenjak, Andreas Öchsner, Zoran Ren, 2007, original scientific article

Abstract: In this paper the behavior of hexagonal honeycombs under dynamic in-plane loading is described. Additionally, the presence and influence of the filler gas inside the honeycomb cells is considered. Such structures are subjected to very large deformation during an impact, where the filler gas might strongly affect their behavior and the capability of deformational energy absorption, especially at very low relative densities. The purpose of this research was therefore to evaluate the influence of filler gas on the macroscopic cellular structure behavior under dynamic uniaxial loading conditions by means of computational simulations. The LS-DYNA code has been used for this purpose, where a fully coupled interaction between the honeycomb structure and the filler gas was simulated. Different relative densities, initial pore pressures and strain rates have been considered. The computational results clearly show the influence of the filler gas on the macroscopic behavior of analyzed honeycomb structures. Because of very large deformation of the cellular structure, the gas inside the cells is also enormously compressed which results in very high gas temperatures and contributes to increased crash energy absorption capability. The evaluated results are valuable for further research considering also the heat transfer in honeycomb structures and for investigations of variation of the base material mechanical properties due to increased gas temperatures under impact loading conditions.
Keywords: mechanics, cellular materials, honeycomb structure, gas filler, thermal properties, mechanical properties, dynamic loading, LS-DYNA, computational simulations
Published in DKUM: 31.05.2012; Views: 2094; Downloads: 73
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