Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208-3113, USA.
Magn Reson Med. 2011 Jan;65(1):220-8. doi: 10.1002/mrm.22587.
Despite recent advances in tissue engineering to regenerate biological function by combining cells with material supports, development is hindered by inadequate techniques for characterizing biomaterials in vivo. Magnetic resonance imaging is a tomographic technique with high temporal and spatial resolution and represents an excellent imaging modality for longitudinal noninvasive assessment of biomaterials in vivo. To distinguish biomaterials from surrounding tissues for magnetic resonance imaging, protein polymer contrast agents were developed and incorporated into hydrogels. In vitro and in vivo images of protein polymer hydrogels, with and without covalently incorporated protein polymer contrast agents, were acquired by magnetic resonance imaging. T(1) values of the labeled gels were consistently lower when protein polymer contrast agents were included. As a result, the protein polymer contrast agent hydrogels facilitated fate tracking, quantification of degradation, and detection of immune response in vivo. For the duration of the in vivo study, the protein polymer contrast agent-containing hydrogels could be distinguished from adjacent tissues and from the foreign body response surrounding the gels. The hydrogels containing protein polymer contrast agent have a contrast-to-noise ratio 2-fold greater than hydrogels without protein polymer contrast agent. In the absence of the protein polymer contrast agent, hydrogels cannot be distinguished by the end of the gel lifetime.
尽管最近在组织工程方面取得了进展，可以通过将细胞与材料支架结合来再生生物功能，但由于缺乏体内生物材料特征描述的技术，其发展受到了阻碍。磁共振成像是一种具有高时间和空间分辨率的层析成像技术，是对体内生物材料进行纵向非侵入性评估的极好的成像方式。为了通过磁共振成像将生物材料与周围组织区分开来，开发了蛋白质聚合物对比剂并将其掺入水凝胶中。通过磁共振成像获得了具有和不具有共价结合的蛋白质聚合物对比剂的蛋白质聚合物水凝胶的体外和体内图像。当包含蛋白质聚合物对比剂时，标记凝胶的 T1 值始终较低。因此，蛋白质聚合物对比剂水凝胶有助于对体内的命运进行跟踪、对降解进行定量以及检测免疫反应。在体内研究期间，含有蛋白质聚合物对比剂的水凝胶可以与相邻组织以及凝胶周围的异物反应区分开来。含有蛋白质聚合物对比剂的水凝胶的对比度噪声比是非蛋白质聚合物对比剂水凝胶的两倍。在没有蛋白质聚合物对比剂的情况下，到凝胶寿命结束时，水凝胶无法被区分。
