ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, Innovation Campus, University of Wollongong, NSW, Australia.
ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, Innovation Campus, University of Wollongong, NSW, Australia; Department of Surgery, St Vincent's Hospital, University of Melbourne, VIC, Australia; BioFab3D, Aikenhead Centre for Medical Discovery, St Vincent's Hospital, Melbourne, VIC, Australia.
Acta Biomater. 2022 Jul 15;147:129-146. doi: 10.1016/j.actbio.2022.05.037. Epub 2022 May 25.
In this work we present a standardised quantitative ultrasound imaging (SQUI) approach for the non-destructive three-dimensional imaging and quantification of cartilage formation in hydrogel based bioscaffolds. The standardised concept involves the processing of ultrasound backscatter data with respect to an acellular phantom in combination with the compensation of sound speed mismatch diffraction effects between the bioscaffold and the phantom. As a proof-of-concept, the SQUI approach was tested on a variety of bioscaffolds with varying degree of neocartilage formation. These were composed of Gelatine Methacryloyl (GelMA) hydrogels laden with human adipose-derived stem cells (hADSCs). These were cultured under chondrogenic stimulation following a previously established protocol, where the degree of the neocartilage formation was modulated using different GelMA network densities (6, 8, 10 % w/v) and culture time (0, 14, 28 days). Using the SQUI approach we were able to detect marked acoustic and morphological changes occurring in the bioscaffolds a result of their different chondrogenic outcome. We defined an acoustic neocartilage indicator, the sonomarker, for the selective imaging and quantification of neocartilage formation. The sonomarker, of backscatter intensity logIBC -2.4, was found to correlate with data obtained via standard destructive bioassays. The ultrasonic evaluation of human specimens confirmed the sonomarker as a relevant intensity, although it was found to shift to higher intensity values in proportion to the cartilage condition as inferred from sound speed measurements. This study demonstrates the potential of the SQUI approach for the realization of non-destructive analysis of cartilage regeneration over-time. STATEMENT OF SIGNIFICANCE: As tissue engineering strategies for neocartilage regeneration evolve towards clinical implementation, alternative characterisation approaches that allow the non-destructive monitoring of extracellular matrix formation in implantable hydrogel based bioscaffolds are needed. In this work we present an innovative standardized quantitative ultrasound imaging (SQUI) approach that allows the non-destructive, volumetric, and quantitative evaluation of neocartilage formation in hydrogel based bioscaffolds. The standardised concept aims to provide a robust approach that accounts for the dynamic changes occurring during the conversion from a cellular bioscaffold towards the formation of a neocartilage construct. We believe that the SQUI approach will be of great benefit for the evaluation of constructs developing neocartilage, not only for in-vitro applications but also potentially applicable to in-vivo applications.
在这项工作中，我们提出了一种标准化的定量超声成像（SQUI）方法，用于无损三维成像和量化水凝胶基生物支架中的软骨形成。该标准化概念涉及到对无细胞幻影进行超声背散射数据处理，同时补偿生物支架和幻影之间的声速不匹配衍射效应。作为概念验证，我们在具有不同程度新软骨形成的各种生物支架上测试了 SQUI 方法。这些支架由明胶甲基丙烯酰（GelMA）水凝胶组成，负载有人脂肪来源干细胞（hADSCs）。这些细胞按照先前建立的方案在软骨诱导刺激下培养，其中通过使用不同的 GelMA 网络密度（6、8、10%w/v）和培养时间（0、14、28 天）来调节新软骨形成的程度。使用 SQUI 方法，我们能够检测到生物支架中发生的明显的声学和形态变化，这是它们不同的软骨生成结果。我们定义了一个声学新软骨指标，即声标志物，用于选择性成像和量化新软骨形成。声标志物的背散射强度 logIBC-2.4 与通过标准破坏性生物测定获得的数据相关。对人体标本的超声评估证实了声标志物是一个相关的强度，尽管发现它随着从声速测量推断出的软骨状况而向更高的强度值偏移。这项研究表明，SQUI 方法有可能实现对软骨再生的非破坏性分析。
随着组织工程策略向新的软骨再生的临床应用发展，需要替代的特征化方法来允许对可植入水凝胶基生物支架中的细胞外基质形成进行无损监测。在这项工作中，我们提出了一种创新的标准化定量超声成像（SQUI）方法，该方法允许对水凝胶基生物支架中的新软骨形成进行无损、体积和定量评估。该标准化概念旨在提供一种稳健的方法，该方法考虑了从细胞生物支架向新软骨结构形成的转化过程中发生的动态变化。我们相信，SQUI 方法将对新软骨形成的构建体的评估非常有益，不仅适用于体外应用，而且可能适用于体内应用。
