Nanotracer Development to Track Stem Cell Therapy

项目摘要 外周动脉疾病（PAD）是一种心血管疾病，可以减少血液流动， 下肢最终导致肢体丧失的可能性。PAD患者的早期临床试验 已经证明了自体干细胞治疗的安全性， 在再灌注和保肢方面略有改善。虽然干细胞疗法可能因此 代表了传统血运重建疗法的现实替代方案， 这限制了大规模的临床试验和广泛使用。临床结局 疗效一直不太理想，主要归因于有充分证据证明的细胞损失， 交付.绝大多数（> 90%）的细胞在植入1-2周后不能存活。 我们已经描述了一种可降解的水凝胶基质可以改善干细胞介导的肌肉 缺血性损伤后的功能恢复。我们的数据表明，一种机制，改善 恢复是在损伤部位维持的细胞数量增加， 对宿主反应的影响我们理解的核心是能够跟踪茎的必要性 细胞和浸润性炎性细胞，特别是巨噬细胞。的重大挑战 临床应用的干细胞治疗的发展仍然缺乏用于干细胞追踪的技术， 提高细胞活力的方法和理解干细胞介导的宿主的策略 反应因此，当前提案的总体目标是了解输送的股骨柄的作用 细胞和修复机制在体内使用纳米示踪剂增强，高分辨率结合 超声和光声（US/PA）成像。第二个目标是能够量化 在模型系统中招募巨噬细胞，我们能够将成像定量与 肌肉功能的定量测量。 我们在这里建议利用等离子体金纳米壳作为纳米示踪剂，由于它们的优异性能， 生物相容性以及可调的强光吸收特性。与其他成像相比， 技术，联合US/PA成像可以在广泛的范围内可视化和量化细胞递送和功能。 时间尺度、空间分辨率和成像深度的范围。组织的高分辨率成像是 以及3D可视化。纳米示踪剂与US/PA成像的组合导致 独特的方法，使我们能够回答有关MSC参与的基本问题， 肌肉修复以及验证临床上可转化的组织再生解决方案。我们建议 在后肢缺血的小鼠模型中开发这个单一系统， 肌肉功能，从而允许与组织再生相关。

Project Summary Peripheral artery disease (PAD) is a form of cardiovascular disease that can reduce blood flow in the lower limbs ultimately resulting in the potential for loss of limb. Early clinical trials in patients with PAD resulting in critical limb ischemia have demonstrated the safety of autologous stem cell therapies with modest improvements in reperfusion and limb salvage. While stem cell therapies may therefore represent a realistic alternative to conventional revascularization therapies, a number of challenges remain which limit large-scale clinical trials and widespread use. Outcomes with respect to clinical efficacy have been less than ideal and are largely attributed to the well-documented cell loss following delivery. The overwhelming majority (>90 %) of cells do not survive implantation after 1-2 weeks. We have described that a degradable hydrogel matrix can improve stem cell-mediated muscle function recovery following ischemic injury. Our data suggested that one mechanism for improved recovery was the increased number of cells that were maintained at the site of injury and their beneficial effects on the host response. Central to our understanding is the necessity of being able to track stem cells and the infiltrating inflammatory cells, particularly macrophages. Major challenges to the development of clinically applied stem cell therapy remains the lack of technologies for stem cell tracking, methods for the improvement of cell viability and strategies to understand the stem cell-mediated host response. Therefore, the overall goal of the current proposal is to understand the role of delivered stem cells and the mechanisms of repair in vivo using nanotracer-enhanced, high-resolution combined ultrasound and photoacoustic (US/PA) imaging. A secondary goal is to be able to quantify the role of recruited macrophages in a model system in which we are able to correlate imaging quantification with quantitative measures of muscle function. We propose here to utilize plasmonic gold nanoshells as nanotracers, due to their excellent biocompatibility, as well as tunable, strong optical absorption properties. In contrast with other imaging techniques, combined US/PA imaging can visualize and quantify cell delivery and function over a broad range of timescales, spatial resolutions and imaging depths. High-resolution imaging of tissues is possible as well as visualization in 3D. The combination of nanotracers with US/PA imaging results in a unique approach that will allow us to answer fundamental questions regarding MSC involvement in muscle repair as well as validate a clinically translatable solution for tissue regeneration. We propose to develop this single system in a mouse model of hindlimb ischemia in which we are able to quantify muscle function, thereby allowing correlation with tissue regeneration.