Ultra-sensitive and multiplexed tracking of single cells using whole-body PET/CT

In vivo molecular imaging tools are crucially important for elucidating how cells move through complex biological systems, however, achieving single-cell sensitivity over the entire body remains challenging. Here, we report a highly sensitive and multiplexed approach for tracking upwards of 20 single cells simultaneously in the same subject using positron emission tomography (PET). The method relies on a statistical tracking algorithm (PEPT-EM) to achieve a sensitivity of 4 Bq/cell, and a streamlined workflow to reliably label single cells with over 50 Bq/cell of 18F-fluorodeoxyglucose (FDG). To demonstrate the potential of the method, we tracked the fate of over 70 melanoma cells after intracardiac injection and found they primarily arrested in the small capillaries of the pulmonary, musculoskeletal, and digestive organ systems. This study bolsters the evolving potential of PET in offering unmatched insights into the earliest phases of cell trafficking in physiological and pathological processes and in cell-based therapies.

活体分子成像工具对于阐明细胞在复杂生物系统中的迁移机制至关重要，但在全身范围内实现单细胞检测灵敏度仍极具挑战。本研究报道了一种高灵敏度多重成像方法，可借助正电子发射断层成像（positron emission tomography, PET）在同一受试个体体内同时追踪超过20个单细胞。该方法依托统计追踪算法（PEPT-EM）实现了4 Bq/细胞的检测灵敏度，并通过精简优化的实验流程，可使用活度超50 Bq/细胞的18F-氟代脱氧葡萄糖（18F-fluorodeoxyglucose, FDG）对单细胞实现稳定标记。为验证该方法的应用潜力，本研究对70余个经心内注射的黑色素瘤细胞的迁移与存活轨迹进行了追踪，发现这些细胞主要阻滞于肺部、肌肉骨骼系统及消化器官系统的微小毛细血管中。本研究进一步凸显了PET日益增长的应用潜力：其可为生理、病理过程及细胞治疗中的细胞迁移早期阶段提供无与伦比的深入见解。