A new multi-scale x-ray micro computed tomography machine to enable (image-guided) non-destructive inspections of decellularised tissue

新型多尺度 X 射线微型计算机断层扫描机，可对脱细胞组织进行（图像引导）无损检查

• 批准号: EP/T029080/1
• 负责人: Charlotte Hagen
• 金额: $ 29.56万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FT029080%2F1
• 关键词: new; multi; scale; ray; micro

Tissue engineering - aimed at developing "lab-grown" organs and tissue by combining appropriate scaffolds and cells - could solve one of the biggest medical problems of our times, the shortage of donor organs. While the pool of scaffold materials is large (e.g. natural/synthetic biomaterials), there is consensus that the extracellular matrix (ECM) of the target tissue is an excellent choice as it possesses native structural and biomechanical properties. ECMs can be derived from cadaver tissue (e.g. from animals) through a process called decellularization, by which the tissue undergoes several cycles of flushing with detergents and enzymes. A successfully decellularised tissue is characterised by the absence of cellular material and the presence of an intact ECM. Imaging, for assessing the ECM, is an extremely important tool for the development of decellularisation methods that are simultaneously gentle and effective.This project is about developing a new imaging tool for characterising decellularised tissue based on x-ray micro computed tomography (CT). Since micro-CT is a non-destructive technique, the inspected samples can be used further in longitudinal studies or be implanted into animals to test their performance in vivo. In comparison, the current gold standard techniques for inspecting ECMs (histology, electron microscopy) require that samples are sliced, sectioned and/or stained in preparation for being imaged, prohibiting using them in any further studies. A number of substantial developments will be needed before micro-CT can become a valuable tool for validating decellularisation techniques and other methodologies in tissue engineering. Currently, micro-CT fails to meet the complex imaging needs of this field, which often requires multi-scale and multi-contrast approaches. First, a micro-CT machine with zooming in capabilities would be required to inspect the multi-level structure of ECMs. Second, decellularised tissue generally exhibits weak x-ray attenuation; hence, the micro-CT machine should provide access to phase contrast alongside attenuation contrast, which is known to provide a much better visualisation of tissue scaffolds than the latter. The micro-CT machine proposed here will have both these functionalities. It will exploit an innovative imaging mechanism that is underpinned by the idea to structure the x-ray beam into an array of narrow (micrometric) beamlets via a mask placed immediately upstream of the sample. This provides flexibility in terms of spatial resolution, as this metric - unlike in conventional micro-CT scanners - is not defined by the blur of the source and detector. Instead, resolution is driven by the beamlet width, which can be made smaller than the intrinsic system blur, bearing unique potential for fast resolution switching and multi-scale imaging. Second, it provides access to complementary contrast channels (phase, ultra-small angle x-ray scattering). These channels result from small x-ray photon deviations which occur alongside attenuation when x-rays interact with matter. While most conventional micro-CT scanners are blind to these effects, the machine proposed here will enable their detection, allowing to reconstruct three sets of complementary tomographic images for each sample. While the phase channel can provide a much higher contrast-to-noise ratio than the attenuation channel, the ultra-small angle x-ray scattering channel encodes the presence of sub-resolution features in a sample. The latter bears unique potential for image-guided zooming in. The project will culminate in the design, construction and test of an experimental prototype for image-guided multi-scale and multi-contrast imaging with a field of view of up to 10 cm by 10 cm, which may be expanded to larger dimensions in the future. A broad range of decellularised tissues will be scanned, and the results benchmarked against the current gold standard (histology or electron microscopy).

组织工程--旨在通过结合合适的支架和细胞来开发“实验室生长”的器官和组织--可以解决我们这个时代最大的医学问题之一，即供体器官的短缺。虽然支架材料的库很大（例如天然/合成生物材料），但人们一致认为靶组织的细胞外基质（ECM）是一个很好的选择，因为它具有天然的结构和生物力学特性。ECM可以通过称为脱细胞化的过程从尸体组织（例如来自动物）获得，通过该过程，组织经历用洗涤剂和酶冲洗的几个循环。成功脱细胞化的组织的特征在于不存在细胞物质和存在完整的ECM。用于评估ECM的成像是开发同时温和和有效的去细胞化方法的一个非常重要的工具。该项目是关于开发一种新的成像工具，用于表征基于X射线显微计算机断层扫描（CT）的去细胞化组织。由于micro-CT是一种非破坏性技术，因此检查的样品可以进一步用于纵向研究或植入动物体内以测试其体内性能。相比之下，目前用于检查ECM的金标准技术（组织学，电子显微镜）要求将样品切片，切片和/或染色以准备成像，禁止在任何进一步的研究中使用它们。在微型CT成为验证去细胞化技术和组织工程中其他方法的有价值的工具之前，需要大量的实质性发展。目前，微型CT无法满足该领域的复杂成像需求，这通常需要多尺度和多对比度方法。首先，需要具有放大能力的微型CT机来检查ECM的多级结构。其次，去细胞化组织通常表现出弱的X射线衰减;因此，微型CT机应该提供与衰减对比度一起的相位对比度，已知这比后者提供更好的组织支架可视化。这里提出的微型CT机将具有这两种功能。它将利用一种创新的成像机制，该机制的基础是通过放置在样品上游的掩模将X射线束结构化为窄（微米）细光束阵列。这在空间分辨率方面提供了灵活性，因为与传统的微型CT扫描仪不同，该度量不是由源和检测器的模糊来定义的。相反，分辨率由细光束宽度驱动，细光束宽度可以小于固有系统模糊，具有快速分辨率切换和多尺度成像的独特潜力。其次，它提供了对互补造影通道（相位、超小角度X射线散射）的访问。这些通道是由小的x射线光子偏差引起的，当x射线与物质相互作用时，这种偏差会伴随着衰减而发生。虽然大多数传统的微型CT扫描仪对这些影响是盲目的，但这里提出的机器将能够检测这些影响，允许为每个样本重建三组互补的断层图像。虽然相位通道可以提供比衰减通道高得多的对比度噪声比，但是超小角度X射线散射通道对样品中亚分辨率特征的存在进行编码。后者在图像引导放大方面具有独特的潜力。该项目最终将设计、建造和测试一个图像引导多尺度和多对比度成像的实验原型，其视野可达10厘米乘10厘米，未来可能扩大到更大的尺寸。将扫描广泛的去细胞化组织，并将结果与当前的金标准（组织学或电子显微镜）进行比较。