Photoacoustic imaging of mesenchymal stem cells in living mice via silica-coated gold nanorods
Photoacoustic imaging of mesenchymal stem cells in living mice via silica-coated gold nanorods
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DOI：
10.1117/12.2036786
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发表时间：
2014-03
影响因子：
0.6
通讯作者：
J. Jokerst;Mridhula Thangaraj;S. Gambhir
中科院分区：
文献类型：
--
作者：
J. Jokerst;Mridhula Thangaraj;S. Gambhir
成像是干细胞治疗的关键，以监测植入细胞的位置、数量和状态(S)。特别是实时成像技术，可以确保适当的细胞输送，以实现最佳植入。然而，现有的成像工具，如磁共振成像，在分娩期间用于指导的时间分辨率受到限制。相比之下，光声成像非常适合于实时、图像引导的治疗。在这里，我们使用二氧化硅包覆的金纳米棒作为光声造影剂，并在植入活体小鼠肌肉组织的过程中将其应用于间充质干细胞的成像和定量。用标准方法制备了二氧化硅包裹的金纳米棒(SiGNR)，并将其负载到间充质干细胞(MSCs)中，而不使用转染剂。MSCs与0.05 nM的SiGNRs孵育3小时后，对细胞增殖无明显影响(p<；0.05)。一组细胞因子应该只是轻微上调包括白细胞介素6在内的炎症标志物。我们使用电子显微镜来显示细胞内的空泡结合的siGNRs。与没有造影剂的MSCs相比，这种细胞染色增加了175%的光声信号--相对于未包覆的GNR，二氧化硅涂层本身增加了55%的信号。利用电感耦合等离子体光谱，我们发现每个MSC有100,000个SiGNRs。这一数值是在没有硅胶涂层的情况下用GNRs染色的MSC群体的5倍。标记后，细胞被清洗并注射到小鼠肌肉组织中，以模拟肌肉营养不良患者。用这些SiGNR标记的MSCs治疗的小鼠(N=5)没有表现出不良反应，并且很容易看到深达5 mm的植入物。在小鼠大腿肌肉中的体内检测下限为每100微升肌肉中90,000个细胞。在这里，B模式信号对于定位治疗区域和可视化输送导管是有用的，而光声模式提供细胞特定内容。MSC移植后的光声信号被组织学验证为一种长期的荧光跟踪染料。
Imaging is crucial for stem cell therapy to monitor the location(s), numbers, and state of the implanted cells. Real-time imaging in particular can ensure proper cell delivery for best engraftment. However, established imaging tools such as MRI are limited by their temporal resolution for guidance during delivery. In contrast, photoacoustic imaging is ideally suited for real time, image-guided therapy. Here, we use silica-coated gold nanorods as photoacoustic contrast agents and deploy them to image and quantitate mesenchymal stem cells during implant into the muscle tissue of live mice. Silica-coated gold nanorods (SiGNRs) were created with standard methods and loaded into mesenchymal stem cells (MSCs) without transfection agents. There was no significant (p<0.05) toxicity or changes to cell proliferation after incubating MSCs with 0.05 nM SiGNRs for 3 hours. A panel of cytokines should only minor upregulation of inflammatory markers including interleukin-6. We used electron microscopy to illustrate vacuole-bound SiGNRs inside the cells. This cell staining increased photoacoustic signal 175% relative to MSCs without contrast agent—the silica coat itself increased signal 55% relative to uncoated GNRs. Using inductively coupled plasma spectroscopy, we found that there were 100,000 SiGNRs per MSC. This value was 5-fold higher than a MSC population stained with GNRs in the absence of silica coat. After labeling, cells were washed and injected into murine muscle tissue to simulate a muscular dystrophy patient. Mice (N=5) treated with these SiGNRlabeled MSCs exhibited no adverse events and implants up to 5 mm deep were easily visualized. The in vivo detection limit was 90,000 cells in a 100 uL bolus in mouse thigh muscle. Here, the B-mode signal is useful for orienting the treatment area and visualizing the delivery catheter while the photoacoustic mode offers cell-specific content. The photoacoustic signal was validated with histology a long-term fluorescent tracking dye after MSC transplant.