Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
NMR Biomed. 2021 Dec;34(12):e4600. doi: 10.1002/nbm.4600. Epub 2021 Aug 18.
Natural killer (NK) cell therapies are being increasingly used as an adoptive cell therapy for cancer because they can recognize tumor cells in an antigen-independent manner. While promising, the understanding of NK cell persistence, particularly within a harsh tumor microenvironment, is limited. Fluorine-19 ( F) MRI is a noninvasive imaging modality that has shown promise in longitudinally tracking cell populations in vivo; however, it has not been studied on murine NK cells. In this study, the impact of F labeling on murine NK cell viability and function was assessed in vitro and then used to quantify NK cell persistence in vivo. While there was no noticeable impact on viability, labeling NK cells with F did attenuate cytotoxicity against lymphoma cells in vitro. Fluorescent microscopy verified F labeling in both the cytoplasm and nucleus of NK cells. Lymphoma-bearing mice were given intratumoral injections of F-labeled NK cells in which signal was detectable across the 6 day observation period via F MRI. Quantification from the composite images detected 78-94% of the initially injected NK cells across 6 days, with a significant decrease between Days 3 and 6. Postmortem flow cytometry demonstrated retention of F intracellularly within adoptively transferred NK cells with less than 1% of F-containing cells identified as tumor-associated macrophages that presumably ingested nonviable NK cells. This work demonstrates that F MRI offers a specific imaging platform to track and quantify murine NK cells within tumors noninvasively.
自然杀伤 (NK) 细胞疗法作为一种过继性细胞疗法，正在被越来越多地用于癌症治疗，因为它们可以以非依赖抗原的方式识别肿瘤细胞。虽然很有前景，但 NK 细胞持久性的理解，特别是在恶劣的肿瘤微环境中，是有限的。氟-19（ F）磁共振成像（MRI）是一种非侵入性的成像方式，已显示出在体内纵向跟踪细胞群体的潜力；然而，它尚未在鼠 NK 细胞上进行研究。在这项研究中，评估了 F 标记对鼠 NK 细胞活力和功能的体外影响，然后用于体内定量 NK 细胞的持久性。虽然对活力没有明显影响，但用 F 标记 NK 细胞会减弱其对淋巴瘤细胞的体外细胞毒性。荧光显微镜证实了 NK 细胞的细胞质和细胞核中都有 F 标记。荷瘤小鼠接受了 F 标记的 NK 细胞的肿瘤内注射，在 6 天的观察期内，通过 F MRI 可以在整个肿瘤内检测到信号。来自复合图像的定量分析在 6 天内检测到最初注入的 NK 细胞的 78%-94%，第 3 天和第 6 天之间有显著下降。死后流式细胞术表明，在过继转移的 NK 细胞中，F 细胞内保留，<1%的 F 细胞被鉴定为肿瘤相关巨噬细胞，可能吞噬了非存活的 NK 细胞。这项工作表明， F MRI 提供了一种特异性的成像平台，可以非侵入性地跟踪和定量肿瘤内的鼠 NK 细胞。
