Appel Alyssa A, Ibarra Veronica, Somo Sami I, Larson Jeffery C, Garson Alfred B, Guan Huifeng, McQuilling John Patrick, Zhong Zhong, Anastasio Mark A, Opara Emmanuel C, Brey Eric M
1 Department of Biomedical Engineering, Illinois Institute of Technology , Chicago, Illinois.
2 Research Services, Edward Hines Jr. VA Hospital , Chicago, Illinois.
Tissue Eng Part C Methods. 2016 Nov;22(11):1038-1048. doi: 10.1089/ten.TEC.2016.0253.
Transplantation of functional islets encapsulated in stable biomaterials has the potential to cure Type I diabetes. However, the success of these materials requires the ability to quantitatively evaluate their stability. Imaging techniques that enable monitoring of biomaterial performance are critical to further development in the field. X-ray phase-contrast (XPC) imaging is an emerging class of X-ray techniques that have shown significant promise for imaging biomaterial and soft tissue structures. In this study, XPC imaging techniques are shown to enable three dimensional (3D) imaging and evaluation of islet volume, alginate hydrogel structure, and local soft tissue features ex vivo. Rat islets were encapsulated in sterile ultrapurified alginate systems produced using a high-throughput microfluidic system. The encapsulated islets were implanted in omentum pouches created in a rodent model of type 1 diabetes. Microbeads were imaged with XPC imaging before implantation and as whole tissue samples after explantation from the animals. XPC microcomputed tomography (μCT) was performed with systems using tube-based and synchrotron X-ray sources. Islets could be identified within alginate beads and the islet volume was quantified in the synchrotron-based μCT volumes. Omental adipose tissue could be distinguished from inflammatory regions resulting from implanted beads in harvested samples with both XPC imaging techniques. Individual beads and the local encapsulation response were observed and quantified using quantitative measurements, which showed good agreement with histology. The 3D structure of the microbeads could be characterized with XPC imaging and failed beads could also be identified. These results point to the substantial potential of XPC imaging as a tool for imaging biomaterials in small animal models and deliver a critical step toward in vivo imaging.
将功能性胰岛封装在稳定的生物材料中进行移植有治愈I型糖尿病的潜力。然而，这些材料的成功需要具备定量评估其稳定性的能力。能够监测生物材料性能的成像技术对于该领域的进一步发展至关重要。X射线相衬（XPC）成像是一类新兴的X射线技术，已显示出在生物材料和软组织结构成像方面具有巨大潜力。在本研究中，XPC成像技术能够对离体胰岛体积、海藻酸盐水凝胶结构和局部软组织特征进行三维（3D）成像和评估。大鼠胰岛被封装在使用高通量微流控系统生产的无菌超纯海藻酸盐系统中。将封装好的胰岛植入1型糖尿病啮齿动物模型中创建的网膜袋中。在植入前用XPC成像对微珠进行成像，并在从动物体内取出后作为整个组织样本成像。使用基于管的X射线源和同步加速器X射线源的系统进行XPC微计算机断层扫描（μCT）。在基于同步加速器的μCT图像中可以识别出海藻酸微珠内的胰岛，并对胰岛体积进行定量。两种XPC成像技术都能在收获的样本中区分网膜脂肪组织和植入微珠引起的炎症区域。通过定量测量观察并量化了单个微珠及其局部封装反应，结果与组织学结果吻合良好。利用XPC成像可以表征微珠的3D结构，还能识别出破裂的微珠。这些结果表明，XPC成像作为一种在小动物模型中对生物材料进行成像的工具具有巨大潜力，并朝着体内成像迈出了关键一步。
