Monitoring of Stem Cell Engraftment in Arthritic Joints with MR Imaging

描述（由申请人提供）：本项目旨在开发一种非侵入性磁共振（MR）成像技术，用于监测人间充质干细胞（hMSC）在关节炎膝关节中的体内活力、归家和植入。中心目标将是证明临床应用的氧化铁磁共振造影剂可以有效地标记hMSC，而不会损害其活力或分化能力，并且这些氧化铁造影剂提供的信号特征可用于诊断关节炎关节中hMSC植入成功或不成功。总的假设是，氧化铁纳米颗粒在磁共振图像上表现出与所研究的移植干细胞的不同生物学状态有关的信号强度差异，并且这些信号差异可以通过磁共振成像检测和量化。我们假设，基于氧化铁的MR造影剂可以通过活细胞和凋亡细胞释放的细胞内氧化铁的t2效应差异来估计移植细胞的活力。在一个系统的、循序渐进的方法中，实验将在细胞培养中进行，然后在体外对有局灶性软骨缺损的猪膝盖进行实验，然后在体内对有局灶性软骨缺损的大鼠膝关节进行实验，最后在体内对患有抗原诱导关节炎的大鼠膝关节进行实验。研究旨在研究氧化铁纳米颗粒标记活的和凋亡的hMSC在这些不同的实验模型中以及标记和/或关节内移植后8周内不同时间间隔的MR信号特征的差异。补充光学成像研究以及电子显微镜、共聚焦显微镜、免疫组织化学和光谱研究将与MR结果相关。这些数据应该阐明所研究的细胞和氧化铁纳米颗粒的生物和物理化学变化，影响观察到的磁共振信号特征。研究结果将有助于关节炎新干细胞疗法的临床前评估、关节炎hMSC治疗相关临床试验的设计，并最终在临床实践中评估这些hMSC治疗方案。公共卫生相关性。发展一种非侵入性成像技术来区分有活力和无活力的供体干细胞，对于监测几乎任何基于干细胞的治疗都是至关重要的。更好地了解造影剂标记活的和凋亡的hMSC在MR图像上的信号行为，可以帮助研究控制干细胞死亡的机制，并引导更有效地使用基于hMSC的关节炎治疗方法。研究结果将对基于hmsc的关节炎和其他关节病变治疗的临床前评估、相关临床试验的设计以及随后在临床实践中评估这些基于干细胞的治疗有直接的帮助。

DESCRIPTION (provided by applicant): This project is designed to develop a non-invasive magnetic resonance (MR) imaging technique for monitoring the in vivo viability, homing and engraftment of human mesenchymal stem cells (hMSC) in arthritic knee joints. Central aim will be to show that clinically applicable iron oxide based MR contrast media can be used to label hMSC effectively without impairment of their viability or differentiation capacity and that signal characteristics, provided by these iron oxide contrast media, may be used to diagnose a successful or non-successful hMSC engraftment in arthritic joints. The overall hypothesis is that iron oxide nanoparticles exhibit differences in signal intensity on MR images with respect to different states of biology of the investigated, transplanted stem cells and that these signal differences can be detected and quantified by MR imaging. We hypothesize, that iron oxide based MR contrast agents can yield estimates of the viability of the transplanted cells by differences in the T2-effect of intracellular iron oxides in viable cells and extracellular iron oxides, released from apoptotic cells. In a systematic, step-by-step approach, experiments will be carried out in cell cultures, then ex vivo in pig knees with focal cartilage defects, then in vivo in knee joints of rats with focal cartilage defects and, finally, in vivo in knee joints of rats with an antigen-induced arthritis. Studies are designed to investigate differences in MR signal characteristics of iron oxide nanoparticle labeled viable and apoptotic hMSC in these different experimental models and at different time intervals up to 8 weeks after labeling and/or intraarticular transplantation. Complementary optical imaging studies as well as electron microscopy, confocal microscopy, immunohistochemistry and spectrometry studies will be correlated with the MR findings. These data should elucidate biological and physicochemical changes of the investigated cells and iron oxide nanoparticles that influence the observed MR signal characteristics. Results should be immediately helpful in the preclinical assessment of new stem cell based therapies for arthritis treatment, in the design of related clinical trials for hMSC therapy of arthritis, and ultimately, in the assessment of those hMSC therapy regimens in clinical practice. PUBLIC HEALTH RELEVANCE. The development of a non-invasive imaging technique for differentiation between viable and non-viable donor stem cells is crucial for monitoring of virtually any stem cell based therapy. A better understanding of the signal behavior of contrast agent labeled viable and apoptotic hMSC on MR images could help to investigate the mechanisms that control stem cell death and lead the way to a more effective use of hMSC-based therapies for arthritis. Results should be immediately helpful in preclinical assessments of hMSC-based therapies of arthritis and other joint pathologies, in the design of related clinical trials, and later, in the assessment of those stem cell based therapies in clinical practice.