Imaging of progenitor cells in tumor environments

干细胞和祖细胞作为基于细胞的疗法都具有重要的前景。 这些细胞具有进行自我更新和分化成各种不同细胞类型的独特能力，从而允许长期持续提供治疗。 额外的好处包括，使用患者自己的细胞，这些细胞的高度控制的体外操作，以及易于交付。 然而，关于这些祖细胞在体内的行为、它们对肿瘤的特异性募集以及体内细胞运输的大小，知之甚少。 利用许多体外和体内成像方法，该提议寻求1）确定介导先前鉴定的祖细胞向肿瘤的明显选择性募集的机制方面，和2）定量不同细胞类型、肿瘤和肿瘤微环境的募集，关于后者，我们最近观察到高效的归巢和保留能力。 我们假设存在独特的肿瘤内皮/祖细胞相互作用，其介导前者在肿瘤中的附着、迁移和分化，特别是通过血管发生的肿瘤微血管。 在初步的可行性研究中，我们已经开发了一些工具，使我们能够在体外和体内询问肿瘤内皮/祖细胞的相互作用。这些工具包括1）分化的内皮细胞的分离和表征（鼠心脏、鼠肺和鼠刘易斯肺癌衍生的内皮）和一组祖细胞（鼠C17.2神经元祖细胞、鼠CD 34+造血干细胞和CD 34 +/Flk-1+内皮祖细胞），2）体外流动室，3）通过光学，核和MR成像方法和4）分离肿瘤归巢细胞用于比较基因组分析的方法。 总之，这些技术以及许多合作者的专业知识将为理解将祖细胞靶向肿瘤的机制提供强有力的方法。 理解在细胞和分子水平上介导祖细胞募集的机制，沿着直接操纵这些事件并促进祖细胞向靶肿瘤的增加募集的能力，将为快速改进和更特异性的基于细胞的治疗直接治疗肿瘤提供跳板。

Both stem cells and progenitor cells hold significant promise as cell-based therapies. These cells have the unique ability to undergo self-renewal and to differentiate into a variety of different cell types, allowing the continued delivery of therapy for a prolonged period. Added benefits include, the use of the patient's own cells, highly controlled in vitro manipulation of these cells, and the ease of delivery. Little is known, however, regarding the behavior of these progenitor cells in vivo, their specific recruitment to tumors and the magnitude of in vivo cell trafficking. Utilizing a number of in vitro and in vivo imaging approaches, this proposal seeks to 1) determine mechanistic aspects that mediate previously identified apparently selective recruitment of progenitor cells to tumors, and 2) quantitate recruitments for different cells types, tumors and tumor microenvironments with regard to the latter we have recently observed highly efficient homing and retention capabilities. We hypothesize that there exist unique tumor endothelium/progenitor cell interactions that mediate attachment, transmigration and differentiation of the former in tumors and in particular the tumor microvasculature through vasculogenesis. In preliminary feasibility studies we have developed a number of tools that will allow us to interrogate tumor endothelium/progenitor cell interactions in vitro and in vivo. These tools include 1) isolation and characterization of differentiated endothelial cells (murine heart, murine lung and murine Lewis Lung carcinoma derived endothelium) and a panel of progenitor cells (murine C17.2 neuronal progenitors, murine CD34+ hematopoietic stem cells and CD34+/Flk-1+ endothelial progenitors), 2) in vitro flow chambers, 3) methods for imaging progenitor cells in vivo by optical, nuclear and MR imaging methods and 4) methods for isolation of tumor homed cells for comparative genomic analysis. Together, these techniques, and the expertise of a number of collaborators, will provide a powerful approach in understanding the mechanisms that target progenitor cells to tumors. Understanding the mechanisms that mediate progenitor cell recruitment both at a cellular and a molecular level, along with the ability to manipulate these events directly and promote increased recruitment of progenitor cells to the target tumor will provide a springboard to rapidly improved and more specific cell-based therapies for the direct treatment of tumor.