Imaging of progenitor cells in tumor environments

干细胞和祖细胞都是基于细胞的治疗方法。这些细胞具有自我更新和分化成各种不同细胞类型的独特能力，从而允许长时间持续提供治疗。额外的好处包括，使用患者自己的细胞，高度控制这些细胞的体外操作，以及易于输送。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和体内细胞运输的大小，我们知之甚少。利用许多体外和体内成像方法，本建议寻求1)确定介导先前确定的祖细胞向肿瘤明显选择性募集的机制方面，以及2)定量募集不同细胞类型，肿瘤和肿瘤微环境，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，通过血管发生介导肿瘤中内皮/祖细胞的附着、转运和分化。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细胞/祖细胞的相互作用。这些工具包括1)分离和鉴定分化内皮细胞（小鼠心脏、小鼠肺和小鼠Lewis肺癌来源的内皮）和祖细胞面板（小鼠C17.2神经元祖细胞、小鼠CD34+造血干细胞和CD34+/Flk-1+内皮祖细胞），2)体外流室，3)祖细胞在体内成像的光学方法，核和磁共振成像方法和4)分离肿瘤归巢细胞的方法，用于比较基因组分析。总之，这些技术，以及许多合作者的专业知识，将为理解以祖细胞为目标的肿瘤机制提供一个强有力的方法。了解在细胞和分子水平上介导祖细胞募集的机制，以及直接操纵这些事件和促进祖细胞募集增加到目标肿瘤的能力，将为快速改进和更特异性的细胞基础疗法提供一个跳板，用于直接治疗肿瘤。

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.