Novel Agents for the Proliferation of Stem Cells

描述（由申请人提供）：多能（未分化）干细胞具有成为人体几乎任何细胞类型的能力，因此，原则上，可用于替换传统上被认为没有显著功能自我修复潜力的器官中的受损组织，如心肌、脊髓、脑组织和肾脏。然而，要实施这些治疗，必须有能力识别、分离和增殖多能干细胞群。第一个问题是，目前鉴定多能干细胞的方法是不够的。我们已经确定了一个新的多能性标记，它可以区分当前方法确定为所有“多能性”的人群中的两种不同细胞类型。其次，胚胎干细胞（ESCs）很难在不启动分化的情况下培养。在目前的技术方案下，培养ESCs只能产生50-75%的未分化菌落。这在很大程度上是由于它们生长在一层“喂食”细胞上，这些细胞分泌一些鲜为人知的因子，其中一些促进未分化干细胞的生长，而另一些无疑会引发分化。邻近细胞分泌的因子影响多能干细胞的分化。例如，多能干细胞可以通过在所需细胞类型的组织上生长而分化成特定的细胞类型。我们所需要的是一种无细胞系统，用于培养ESCs，其中只添加离散的、特性良好的试剂来驱动它们的生长。我们已经成功地在无细胞系统中培养了ESCs，方法是在ESCs表面添加一种激活新发现的生长因子受体的单一试剂，而不是添加来自饲养细胞的条件培养基。由此产生的群体是100%多能性的，并通过我们的新药物的退出发出分化信号。这是了解维持多能性的分子驱动因素以及启动分化的分子驱动因素的重要一步，并将使目前遥不可及的干细胞治疗成为可能。因此，多能干细胞纯池的分离和繁殖将对干细胞治疗应用于脑和脊髓损伤、糖尿病、心力衰竭、视网膜病变的修复至关重要，并进一步使一系列目前不可能的治疗干预成为可能。公共卫生相关性：多能（未分化）干细胞具有成为人体几乎任何细胞类型的能力，因此，原则上可用于替换传统上被认为没有重大功能自我修复潜力的器官中的受损组织，如心肌、脊髓、脑组织和肾脏。然而，要实施这些治疗，必须有能力识别、分离和增殖多能干细胞群。我们已经成功地在无细胞系统中培养了ESCs，方法是在ESCs表面添加一种激活新发现的生长因子受体的单一试剂，而不是添加来自饲养细胞的条件培养基。

DESCRIPTION (provided by applicant): Pluripotent (undifferentiated) stem cells possess the ability to become virtually any cell type in the human body and therefore, in principal, could be used to replace damaged tissues in organs that have traditionally been thought not to have a significant potential for functional self-repair such as heart muscle, spinal cord, brain tissue and kidney. However, to implement these therapies, one must have the ability to identify, isolate and proliferate populations of pluripotent stem cells. The first problem is that current methods for identifying pluripotent stem cells are insufficient. We have identified a new marker of pluripotency that discriminates between two different cell types within a population that current methods identify as being all "pluripotent". Secondly, it is difficult to culture embryonic stem cells (ESCs) without initiating differentiation. Growing ESCs under current state of the art protocols will yield only 50-75% undifferentiated colonies. This is in large part due to the fact that they are grown over a layer of "feeder" cells which secrete poorly understood factors, some of which promote the growth of undifferentiated stem cells and others that undoubtedly trigger differentiation. Factors secreted by neighboring cells influence how pluripotent stem cells differentiate. For example, pluripotent stem cells can be influenced to differentiate into a particular cell type by growing them over tissues of the desired cell type. What is needed is a cell-free system for growing ESCs in which only discrete, well-characterized agents are added to drive their growth. We have succeeded in growing ESCs in a cell-free system by adding a single agent that activates a newly identified growth factor receptor on the surface of ESCs - conditioned media from feeder cells was not added. The resultant population was 100% pluripotent and was signaled to differentiate by the withdrawal of our novel agent. This is a major step toward understanding the molecular drivers that maintain pluripotency as well as those that initiate differentiation and will enable stem cell therapies that are currently out of reach. Thus the isolation and propagation of pure pools of pluripotent stem cells will be critical for therapeutic applications of stem cell therapy for the repair of brain and spinal cord injuries, diabetes, cardiac failure, retinopathies and further will enable a whole range of therapeutic interventions that are currently not possible. PUBLIC HEALTH RELEVANCE: Pluripotent (undifferentiated) stem cells possess the ability to become virtually any cell type in the human body and therefore, in principal, could be used to replace damaged tissues in organs that have traditionally been thought not to have a significant potential for functional self-repair such as heart muscle, spinal cord, brain tissue and kidney. However, to implement these therapies, one must have the ability to identify, isolate and proliferate populations of pluripotent stem cells. We have succeeded in growing ESCs in a cell-free system by adding a single agent that activates a newly identified growth factor receptor on the surface of ESCs - conditioned media from feeder cells was not added.