Ultrasound-Driven ex-vivo Engineering of Tissue-Guiding Hydrogels for Bone Regeneration

该项目旨在发展基于超声的方法，以创建机械、结构和生物可调的组织引导离体结构，用于骨缺损的再生。超声波将在整个项目开发过程中以不同的方式提供。通过超声驻波的应用，可以在原位聚合凝胶中实现间充质基质细胞（MSCs）和脂质体包裹的骨形态发生蛋白-2 （BMP-2）生长因子的成图化组织。这将完成细胞外基质组织，反映支架中的细胞排列，有助于各向异性组织结构的发展。在空间和时间上控制BMP-2从固定脂质体按需释放将由高强度声爆发提供。因此，所需的生长因子浓度可以大大降低，由于bmp -2相关的副作用，这在临床环境中非常有吸引力。此外，低强度脉冲超声将用于促进整个结构中的细胞存活，并进一步降低细胞有效成骨分化所需的BMP-2浓度。合成的支架将进行机械测试，并评估其组织引导性能。扫描声学生物显微镜（SAM）将用于成熟支架的纵向成像，以获得机械材料性能演变的额外信息。本文提出的方法可以进一步适应不同的细胞类型、生物因子和聚合凝胶，用于体外设计旨在再生其他组织的结构。

This project aims at the development of ultrasound-based methodology to create mechanically, structurally and biologically tunable tissue-guiding ex-vivo constructs for regeneration of bone defects. Ultrasound will be supplied in different modes throughout the project development. Via application of ultrasound standing waves, patterned organization of Mesenchymal Stromal Cells (MSCs) and liposome-encapsulated Bone Morphogenetic Protein-2 (BMP-2) growth factor will be achieved in the in-situ polymerizing gel. This will accomplish extracellular matrix organization mirroring cellular alignment in the scaffolds, contributing to the development of anisotropic tissue constructs. Spatially and temporally controlled on-demand release of BMP-2 from the immobilized liposomes will be supplied by a high-intensity acoustic burst. Thereby, the required growth-factor concentration can be considerably reduced, which is highly appealing in the clinical setting due to the BMP-2-associated side effects. Additionally, Low-Intensity Pulsed Ultrasound will be applied to promote cellular survival in the entire construct and to further reduce the BMP-2 concentration necessary for efficient osteogenic differentiation of the cells. The resultant scaffolds will be mechanically tested and their tissue guiding properties will be assessed. Scanning acoustic biomicroscopy (SAM) will be used for longitudinal imaging of the maturing scaffolds, yielding additional information on the evolution of mechanical material properties. The methodology proposed here can be further adapted by varying cell type, biofactor and polymerizing gel for ex-vivo design of constructs aimed at regeneration of other tissues.