A New Platform for Biomechanical Imaging Based on Brillouin Scattering

机体组织的机械变化与多种临床问题广泛相关，包括糖尿病、动脉粥样硬化和癌症等许多严重并发症，但人们对其微观结构基础知之甚少。在大血管中，僵硬与心血管死亡风险增加有关，尽管个体组织成分的僵硬对这种风险的贡献尚不清楚。我们在长度尺度上测量机械性能的能力限制了我们对刚度与结构之间联系机制的理解，而这种能力只能建立与组织结构和成分之间的关系。正如最近发表的一篇文章（Palombo, Madami， Stone和Fioretto， Analyst, 2014, 139, 729-733）所证明的那样，BLS显微镜有可能填补这一空白，其中基于对应于特定组织成分的布里布鲁峰生成结构和弹性的机械图。对细胞和组织的化学成分进行成像的新技术正在生物学和医学的许多领域产生重大影响。本文研究了布里渊光散射成像（BLS）技术的发展，这是一种用于力学性能微观成像的新方法。结缔组织、软骨或血管的力学特性是其生理功能的核心，力学功能的变化与从糖尿病到骨关节炎等疾病有关。因此，BLS成像提供了直接成像组织和单一成分（如胶原蛋白和弹性蛋白纤维）功能重要特性的前景，其生物力学在多个频率下探测几乎完全未被探索，这将打开组织力学的新窗口，并提供开发新诊断技术的前景。该方法的原理是检测样品中声波产生产生的非弹性散射光的频率变化。对波速的计算提供了测量材料力学性能的一种方法。初步研究已经使用共聚焦BLS显微镜生成上皮组织的布里渊频率图，该频率图可以与化学成分的拉曼微光谱图相结合（Palombo等）。分析师2014)。补充研究已经调查了胶原蛋白和弹性蛋白（细胞外基质的纤维蛋白）中的布里渊散射及其与纤维微力学的关系（Palombo等人）。J R Soc接口，asap)。这项工作为拟议的调查提供了基础。该方法将适用于结缔组织生理学和病理学的许多问题，但直接目标将是研究细胞外蛋白纤维的力学-胶原蛋白，弹性蛋白，蛋白多糖-以及生理和病理条件的影响。这些变化与多种临床问题广泛相关，包括骨关节炎和糖尿病的许多严重并发症，但其微观结构基础尚不清楚。该项目将需要构建一个系统，该系统将使用虚拟成像相控阵（VIPA）光谱仪通过布里渊散射进行生物力学成像。这将使我们能够开发出一种更快、更通用的技术来分析纤维（和组织），并确定功能上的重大变化，从长远来看，这些变化可以成为监测或治疗干预的目标。

Mechanical changes in body tissues are widely associated with diverse clinical problems including many of the serious complications of diabetes, atherosclerosis and cancer, but their microstructural bases are poorly understood. In large blood vessels, stiffness is linked to increased risk of cardiovascular mortality - although the contribution of the stiffness from individual tissue constituents to this risk is unknown. Understanding the mechanisms linking stiffness to structure is limited by our ability to measure mechanical properties on length-scales which allow the relationships with tissue structure and composition to be established. BLS microscopy has the potential to fill this void, as demonstrated in a recent publication (Palombo, Madami, Stone and Fioretto, Analyst, 2014, 139, 729-733) where mechanical maps of structure and elasticity were generated based on Brillouin peaks corresponding to specific tissue components. New techniques of imaging the chemical composition of cells and tissues are making a major impact in many fields of biology and medicine. This proposal is concerned with the development of Brillouin light scattering (BLS) imaging, a new method for microscopic imaging of mechanical properties. The mechanical properties of the connective tissues, cartilage or blood vessels are central to their physiological function and changes in mechanical function are implicated in diseases ranging from diabetes to osteoarthritis. BLS imaging therefore offers the prospect of directly imaging a functionally important property, both in tissues and single constituents e.g. collagen and elastin fibres, whose biomechanics probed at multiple frequencies are almost completely unexplored, which will open a new window on tissue mechanics and offers the prospect of developing new diagnostic techniques.The principle of the approach is to detect the change in frequency of inelastically scattered light arising from the generation of sound waves in the sample. Calculation of the speed of the wave provides a measure of the mechanical properties of the material. Preliminary studies have used confocal BLS microscopy to produce Brillouin frequency maps of an epithelial tissue, which can be combined with Raman micro-spectroscopic maps of chemical composition (Palombo et al. Analyst 2014). Complementary studies have investigated Brillouin scattering in collagen and elastin, the fibrous proteins of the extracellular matrix, and their relationships to fibre micromechanics (Palombo et al. J R Soc Interface, asap).This work provides the basis for the proposed investigations. The methodology will be applicable to many problems of connective tissue physiology and pathology, but the immediate aim will be to investigate the mechanics of extracellular protein fibres - collagens, elastin, proteoglycans - and the effects of physiological and pathological conditions. These changes are widely associated with diverse clinical problems including many of the serious complications of osteoarthritis and diabetes, but their microstructural bases are poorly understood. The project will require construction of a system that will enable biomechanical imaging through Brillouin scattering with a Virtually Imaged Phase Array (VIPA) spectrometer. This will enable us to develop a significantly faster and more versatile technology for the analysis of fibres (and tissues) and to define functionally significant changes which can, in the longer term, become targets for monitoring or therapeutic intervention.