Compositions and methods for enhanced fluorine-19 magnetic resonance imaging cell tracking

对于免疫治疗和干细胞等细胞疗法的临床开发者来说，一个共同的需求是一种非 侵入性手段是观察注射后细胞的命运。对细胞贩运的成像可以提供关键的 关于持久性、运动性、最佳给药途径和治疗剂量的反馈。这个项目的目的是 用于灵敏活体细胞示踪的新型新型成像探针的合成和生物学评价 氟-19(19F)磁共振成像(MRI)。我们将推进令人信服的 新型金属全氟化碳(MPFC)纳米乳液成像探针。这些特工将是关键 元件引入多管齐下的策略，将电池检测灵敏度提高一个数量级的过电流 19F磁共振细胞检测技术。总体而言，在19F细胞跟踪中，感兴趣的细胞群最初被标记为 使用全氟碳纳米乳剂进行培养。在转移到受试者之后，体内的细胞被跟踪 19F磁共振成像。细胞内的氟产生细胞特有的图像，没有背景信号。其中一个 阻碍基于19F的细胞跟踪的更广泛采用的瓶颈是对稀疏细胞数量的敏感性限制。 这项技术的灵敏度可以通过三个方面的方法来提高：(1)分子设计和 合成以提高分子信号发生器的本征灵敏度和(2)纳米乳胶探针 使用细胞靶向的配方，以增强细胞内的传递和摄取，以及(3)使用MRI数据 每个采集时间具有更有效的信噪比(SNR/t)的采集方案。最新结果 通过分子设计证明了氟磁共振成像的敏感性显著增强。我们已经创建了一个 将高度氟化的纳米乳液与金属的磁性相结合的新型分子 它们被溶解到氟化物中。溶解的顺磁性金属离子显著减少了 19F自旋-晶格弛豫时间，从而提高了SNR/t和细胞检测灵敏度。人们发现， 铁是增强氟核磁共振信号最有效的金属。根据这些初步结果， 该提案有四个具体目标：目标1.针对MPFC的螯合策略。我们将评估一系列合适的 稳定地将金属离子结合到PFC中的螯合分子和合成策略。目标2.增强单元格 使用细胞穿透肽(CPPs)传递MPFC纳米乳剂。细胞的MRI检测成功 关键是需要在体外最佳的乳化MPFC细胞内给药。我们将开发新型的MPFC 将CPPS结合到纳米乳液表面活性剂上的纳米乳液配方快速和优化 标记单元格以进行单元格跟踪。目标3.“智能”体内靶向纳米乳剂。作为这一概念的探索性延伸 在工作中，我们设计了针对体内肿瘤的MPFC纳米乳剂。目的4.活体成像方法追踪 癌症中的免疫治疗T细胞。为了评估新的MPFC纳米乳液探针，我们将标记T细胞和 将这些应用于免疫治疗癌症模型。为了对这些模型进行成像，稀疏采样MRI采集 将为MPFC代理实施和优化方法(例如，压缩感测)以最大化SNR/t。

A common need for clinical developers of cell therapies, such as immunotherapeutic and stem cells, is a non- invasive means to visualize the fate of cells following injection. Imaging of cell trafficking can provide critical feedback regarding the persistence, motility, optimal routes of delivery and therapeutic doses. This project aims to synthesize and biologically evaluate innovative new imaging probes for sensitive in vivo cell tracking using fluorine-19 (19F) magnetic resonance imaging (MRI). We will advance the formulation science of a compelling new class of ‘metallo-perfluorocarbon’ (MPFC) nanoemulsion imaging probes. These agents will be a key element to a multi-pronged strategy to advance cell detection sensitivity by an order of magnitude over current 19F MRI cell detection technologies. Overall, in 19F cell tracking, cell populations of interest are initially labeled in culture using perfluorocarbon nanoemulsions. Following transfer to the subject, cells are tracked in vivo using 19F MRI. The fluorine inside the cells yields cell-specific images, with no background signal. One of the bottlenecks preventing the broader adoption of 19F based cell tracking is sensitivity limits to sparse cell numbers. The sensitivity of this technology can be improved by a three-pronged approach: (1) molecular design and synthesis to improve the intrinsic sensitivity of the molecular signal generator and (2) nanoemulsion probe formulation with cell targeting to enhance intracellular delivery and uptake, and (3) employing MRI data acquisition schemes that have a more efficient signal-to-noise ratio per acquisition time (SNR/t). Recent results have demonstrated dramatically-enhanced sensitivity of fluorine MRI by molecular design. We have created a new class of molecules that combine highly fluorinated nanoemulsions with the magnetic properties of metals that are solubilized into the fluorous phase. Solubilized paramagnetic metal ions provide a dramatic reduction in the 19F spin-lattice relaxation time thereby enhancing SNR/t and cell detection sensitivity. It was discovered that iron is most effective metal at enhancing the fluorine MRI signal. Building on these preliminary results, the proposal has four Specific Aims: Aim 1. Chelation strategies for MPFCs. We will evaluate a range of suitable chelate molecules and synthesis strategies to stably incorporate metal ions into PFC. Aim 2. Enhanced cell delivery of MPFC nanoemulsion using cell penetrating peptides (CPPs). Successful MRI detection of cells critically requires optimal intracellular delivery of emulsified MPFC ex vivo. We will develop novel MPFC nanoemulsion formulations incorporating CPPs attached to the nanoemulsion surfactant to rapidly and optimally label cells for cell tracking. Aim 3. “Smart” in vivo targeted nanoemulsions. As an exploratory extension of this work, we devise MPFC nanoemulsions that target tumors in vivo. Aim 4. In vivo imaging methods to track immunotherapeutic T cells in cancer. To evaluate new MPFC nanoemulsion probes, we will label T cells and deliver these to immunotherapeutic cancer models. To image these models, sparse sampling MRI acquisition methods (e.g., compressed sensing) will be implemented and optimized for MPFC agents to maximize SNR/t.