Microscale Mechanobiology for Musculoskeletal Tissue Engineering using Advanced Ultrasound Techniques

项目摘要 机械力是细胞微环境的一个关键组成部分，并且已经得到了很好的证实 对细胞和组织有很强的影响。二维细胞衬底的被动力学性能和 三维细胞外基质已被证明可以影响祖细胞的表型，并且可以 用于指导细胞功能。此外，使用外力对细胞和组织进行主动刺激 已经在细胞和组织水平上应用，以诱导各种反应。机械生物学是 尤其与肌肉骨骼组织有关，但我们对物理学的理解存在差距 细胞能感觉到的长度尺度上的组织环境特性。这个项目建立在前期工作的基础上。 由项目组应用先进的超声波技术研究微尺度的物理性质 由细胞种子矿化水凝胶组成的工程化肌肉骨骼组织。它集成了光谱 超声成像(SUSI)、双模超声弹性成像(DUE)和超声诱导压迫 刺激。SUSI是一种使用反向散射射频谱来获取信息的技术 关于样品的成分。施加声辐射力使水凝胶变形及测量 它们的机械性能。聚焦超声诱导的压缩也将声压应用于 机械刺激组织。超声波技术的一个关键特征是它们是非侵入性的 因此可以用来研究随着时间的推移发育中的组织。此外，成像和变形也可以 应用于亚毫米分辨率。该项目将结合这些先进的超声波技术来创造 一种能够全面表征和刺激工程化肌肉骨骼组织的系统 微尺度的。其目标应用是使用间充质干细胞(MSC)促进骨形成 嵌入在3D水凝胶基质中。具体目标是：1)整合频谱超声成像(SUSI) 以及双模超声弹性成像(DUE)，以从成分和力学上表征成矿作用 2)探讨被动基质力学性能对MSC表型的影响。 3)利用超声诱导的细胞周期作用，积极促进MSC在水凝胶基质中的成骨分化。 加压，以及4)应用苏西-因催化和监测体内骨再生。这个项目将 使用一种创新的新工具研究肌肉骨骼机械生物学，这可能对 再生医学。长期目标是一种治疗干预，以促进骨形成 加速愈合将导致改善结果的适应症，如治疗骨不连和 顽固的脊柱融合术。

Project Summary Mechanical forces are a key component of the cellular microenvironment, and are well established to have potent effects on cells and tissues. The passive mechanical properties of two-dimensional cell substrates and three-dimensional extracellular matrices have been shown to influence progenitor cell phenotype and can be used to direct cell function. In addition, active stimulation of cells and tissues using externally applied forces has been applied at both the cell and tissue level to induce a variety of responses. Mechanobiology is particularly relevant to musculoskeletal tissues, but there is a gap in our understanding of the physical properties of the tissue environment on length scales that cells sense. This project builds on preliminary work by the project team in applying advanced ultrasound techniques to studying the microscale physical properties of engineered musculoskeletal tissues composed of cell-seeded mineralizing hydrogels. It integrates spectral ultrasound imaging (SUSI), dual-mode ultrasound elastography (DUE), and ultrasound-induced compressive stimulation. SUSI is a technique that uses the backscattered radiofrequency spectrum to derive information about the composition of a sample. DUE applies acoustic radiation force to deform hydrogels and measure their mechanical properties. Focused ultrasound-induced compression also applies acoustic pressure to mechanically stimulate tissues. A key feature of ultrasound techniques is that they are noninvasive and therefore can be used to study developing tissues over time. In addition, imaging and deformation can be applied at sub-millimeter resolution. This project will combine these advanced ultrasound techniques to create a system that can comprehensively characterize and stimulate engineered musculoskeletal tissues at the microscale. The target application is to potentiate bone formation using mesenchymal stem cells (MSC) embedded in a 3D hydrogel matrix. The Specific Aims are 1) to integrate spectral ultrasound imaging (SUSI) and dual-mode ultrasound elastography (DUE) to compositionally and mechanically characterize mineralizing tissues, 2) to probe the effects of passive matrix mechanical properties on MSC phenotype using SUSI-DUE, 3) to actively stimulate osteogenic differentiation of MSC in hydrogel matrices using ultrasound-induced cyclic compression, and 4) to apply SUSI-DUE to catalyze and monitor bone regeneration in vivo. This project will investigate musculoskeletal mechanobiology using an innovative new tool that could have important impact on regenerative medicine. The long term goal is a therapeutic intervention to potentiate bone formation in indications where accelerated healing would lead to improved outcomes, such as treatment of non-unions and recalcitrant spinal fusions.