New tools for tracking single cells in vivo

摘要 该项目将开发一种新的管道，用于在全身水平跟踪单个细胞在体内的迁移。 细胞迁移是一个关键的生物学过程，参与了世界上一些 最难治的疾病。例如，干细胞疗法和免疫疗法正在成为可行的疗法。 治疗以前被认为是无法治愈的疾病，如心力衰竭和糖尿病。不幸的是，细胞 追踪方法仍然不足以充分利用这些最新进展。目前，细胞跟踪依赖于 通过造影剂对特定细胞群体的分布进行成像，这是直接的 贴在细胞上或针对工程报告蛋白。这种方法排除了精确的 细胞循环动力学或迁移路线的测量。此外，由于外流和非特异性 保留时，造影剂的分布不一定与细胞的基本分布相匹配。 鉴于这些挑战，我们考虑一种新的方法，它有可能彻底改变细胞跟踪。 虽然目前的方法旨在跟踪大量细胞，但我们假设新的生物学洞察力可能 通过以前所未有的时间和空间精确度对单个细胞进行少量跟踪来获得。 我们将继续开发CellGPS，这是一种能够跟踪单个细胞的3D位置的方法 随着这些细胞在活着的受试者体内不断迁移。为了实现这一目标，我们依赖于 以前开发的算法，可以直接从原始列表模式提取移动单元格的位置 正电子发射断层扫描(PET)扫描仪的输出。PET是可用的最灵敏的成像方式 用于全身人体成像，因此是该项目的理想成像方式。建立在广泛的基础上 初步研究后，我们计划追求以下四个具体目标：(1)发展快速、安全和稳健的 放射性标记细胞的策略；(2)设计和建造一种新型的微流控管道，用于分子图谱和 分离单个细胞用于活体跟踪；(3)评估单个细胞跟踪作为细胞扩散的读数 转移性黑色素瘤的实验模型；以及(4)探索将这项技术转化为人类成像 扫描仪。该项目有望对临床前的生物医学研究产生积极的影响 和临床环境。例如，单细胞跟踪可以用来确定 在转移级联的最早阶段的细胞迁移。该方法还可以帮助确定 细胞移植后细胞的动态分布，有助于预测反应和 优化治疗方案。该项目将实现常规化和可重复性的关键里程碑 利用正电子发射计算机断层扫描技术对体内单个细胞进行追踪。

Abstract This project will develop a new pipeline for tracking the migration of single cells in vivo at the whole-body level. Cell migration is a crucial biological process involved in the pathology and treatment of some of the world’s most intractable diseases. Stem cell therapy and immunotherapy, for instance, are emerging as viable treatments for conditions previously thought incurable, such as heart failure and diabetes. Unfortunately, cell tracking methods remain inadequate to fully capitalize on these recent advances. Currently, cell tracking relies on imaging the distribution of a specific population of cell through a contrast agent, which is either directly affixed to the cells or targeted towards an engineered reporter protein. This approach precludes precise measurement of cell circulation kinetics or migration routes. Furthermore, due to efflux and non-specific retention, the distribution of the contrast agent does not necessarily match the underlying distribution of cells. In view of these challenges, we consider a novel approach that has the potential to revolutionize cell tracking. While current methods aim to track bulk populations of cells, we hypothesize that novel biological insight may be gained by tracking cells individually, in small numbers, with unprecedented temporal and spatial accuracy. We will pursue the development of CellGPS, a method capable of tracking the 3D position of individual cells continuously as these cells migrate through the body of a living subject. To accomplish this goal, we rely on a previously developed algorithm that can extract the position of a moving cell directly from the raw list-mode output of a positron emission tomography (PET) scanner. PET is the most sensitive imaging modality available for whole-body human imaging and, therefore, the ideal imaging modality for this project. Building on extensive preliminary studies, we plan to pursue the following four specific aims: (1) develop a rapid, safe and robust strategy for radiolabeling cells; (2) design and build a novel microfluidics pipeline to molecularly profile and isolate single cells for in vivo tracking; (3) evaluate single-cell tracking as a readout of cell dissemination in an experimental model of metastatic melanoma; and (4) explore translation of this technology to human imaging scanners. This project is expected to generate a positive impact for biomedical research both in the pre-clinical and clinical setting. For instance, single-cell tracking could be used to determine the spatiotemporal kinetics of cell migration during the earliest phase of the metastatic cascade. The method could also help determine the dynamic distribution of cells after transplantation for cell-based therapy, which could help predict response and optimize treatment regimen. This project will achieve critical milestones towards routine and reproducible tracking of single cells in vivo using PET.