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无创磁共振（MR）成像技术，用于监测关节炎膝关节中人间充质干细胞（hMSC）的体内活力、归巢和植入。主要目的是证明临床上适用的基于氧化铁的MR造影剂可用于有效标记hMSC，而不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。总体假设是，氧化铁纳米颗粒在MR图像上表现出相对于所研究的移植干细胞的不同生物学状态的信号强度差异，并且这些信号差异可以通过MR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中的细胞内氧化铁和凋亡细胞释放的细胞外氧化铁的T2效应的差异来估计移植细胞的活力。在系统的、逐步的方法中，实验将在细胞培养物中进行，然后在具有局灶性软骨缺损的猪膝关节中离体进行，然后在具有局灶性软骨缺损的大鼠膝关节中体内进行，最后在具有抗原诱导的关节炎的大鼠膝关节中体内进行。研究旨在研究在这些不同的实验模型中，以及在标记和/或关节内移植后长达8周的不同时间间隔，氧化铁纳米颗粒标记的活的和凋亡的hMSC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学研究将与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学和物理化学变化，这些变化影响所观察到的MR信号特征。结果应该立即有助于临床前评估的新的干细胞为基础的疗法治疗关节炎，在设计相关的临床试验hMSC治疗关节炎，并最终在临床实践中的hMSC治疗方案的评估。公共卫生相关性。开发一种非侵入性的成像技术，用于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的活的和凋亡的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，并为更有效地使用基于hMSC的关节炎疗法开辟道路。这些结果应该立即有助于关节炎和其他关节病变的基于hMSC的治疗的临床前评估，相关临床试验的设计，以及后来在临床实践中对这些基于干细胞的治疗的评估。

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.