Celsense, Inc., Department of Research and Development, Pittsburgh, PA, USA.
Cell Transplant. 2013;22(1):87-97. doi: 10.3727/096368912X653174. Epub 2012 Aug 2.
Hematopoietic stem cells (HSCs) have numerous therapeutic applications including immune reconstitution, enzyme replacement, regenerative medicine, and immunomodulation. The trafficking and persistence of these cells after administration is a fundamental question for future therapeutic applications of HSCs. Here, we describe the safe and efficacious labeling of human CD34(+) HSCs with a novel, self-delivering perfluorocarbon ¹⁹F magnetic resonance imaging (MRI) tracer, which has recently been authorized for use in a clinical trial to track therapeutic cells. While various imaging contrast agents have been used to track cellular therapeutics, the impact of this MRI tracer on HSC function has not previously been studied. Both human CD34(+) and murine bone marrow (BM) HSCs were effectively labeled with the MRI tracer, with only a slight reduction in viability, relative to mock-labeled cells. In a pilot study, ¹⁹F MRI enabled the rapid evaluation of HSC delivery/retention following administration into a rat thigh muscle, revealing the dispersal of HSCs after injection, but not after surgical implantation. To investigate effects on cell functionality, labeled and unlabeled human HSCs were tested in in vitro colony forming unit (CFU) assays, which resulted in equal numbers of total CFU as well as individual CFU types, indicating that labeling did not alter multipotency. Cobblestone assay forming cell precursor frequency was also unaffected, providing additional evidence that stem cell function was preserved after labeling. In vivo tests of multipotency and reconstitution studies in mice with murine BM containing labeled HSCs resulted in normal development of CFU in the spleen, compared to unlabeled cells, and reconstitution of both lymphoid and myeloid compartments. The lack of interference in these complex biological processes provides strong evidence that the function and therapeutic potential of the HSCs are likely maintained after labeling. These data support the safety and efficacy of the MRI tracer for clinical tracking of human stem cells.
造血干细胞（HSCs）具有许多治疗应用，包括免疫重建、酶替代、再生医学和免疫调节。这些细胞在给药后的迁移和持久性是未来 HSCs 治疗应用的一个基本问题。在这里，我们描述了一种新型自递呈全氟化碳 ¹⁹F 磁共振成像（MRI）示踪剂对人 CD34(+)HSCs 的安全有效标记，该示踪剂最近已被授权用于一项临床试验以跟踪治疗细胞。虽然已经使用了各种成像对比剂来跟踪细胞治疗，但以前尚未研究过这种 MRI 示踪剂对 HSC 功能的影响。人 CD34(+)和鼠骨髓（BM）HSCs 均被该 MRI 示踪剂有效标记，与模拟标记细胞相比，仅略有活力降低。在一项初步研究中，¹⁹F MRI 能够快速评估 HSC 给药后在大鼠大腿肌肉中的递送/保留情况，显示出注射后 HSCs 的分散，但在手术植入后没有分散。为了研究对细胞功能的影响，对标记和未标记的人 HSCs 进行了体外集落形成单位（CFU）测定，结果显示总 CFU 和单个 CFU 类型的数量相等，表明标记不会改变多能性。鹅卵石 assay 形成细胞前体频率也不受影响，进一步证明标记后干细胞功能得以保留。体内多能性测试和含有标记 HSCs 的鼠 BM 进行的重建研究导致脾 CFU 的正常发育，与未标记细胞相比，并且重建了淋巴和髓样细胞区室。这些复杂的生物学过程不受干扰提供了强有力的证据，表明 HSCs 的功能和治疗潜力在标记后很可能得到维持。这些数据支持 MRI 示踪剂用于临床追踪人类干细胞的安全性和有效性。
