Novel Agents for the Proliferation of Stem Cells

描述(申请人提供)：多能(未分化)干细胞具有成为人体内几乎任何类型细胞的能力，因此，原则上可以用来取代传统上被认为不具有显著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，要实施这些疗法，必须有能力识别、分离和增殖多能干细胞群体。第一个问题是，目前识别多能干细胞的方法是不够的。我们已经确定了一种新的多能性标记，它可以区分一个群体中的两种不同类型的细胞，目前的方法认为这两种细胞类型都是“多能性”的。其次，如果不启动分化，很难培养胚胎干细胞(ESCs)。在目前最先进的方案下培养ESCs将只产生50%-75%的未分化克隆。这在很大程度上是因为它们生长在一层“滋养”细胞上，这些细胞分泌人们知之甚少的因子，其中一些促进未分化干细胞的生长，另一些无疑会引发分化。邻近细胞分泌的因素会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来影响其分化为特定的细胞类型。需要的是一种无细胞系统来培养ESCs，在该系统中只添加离散的、特征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生长ESCs，通过添加一种单一的试剂来激活来自饲养细胞的ESCs条件培养液表面新发现的生长因子受体。由此产生的种群是100%多能的，并通过我们的新制剂的退出而被发出分化的信号。这是朝着理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迈出的重要一步，这些分子驱动因素将使目前遥不可及的干细胞疗法成为可能。因此，分离和繁殖纯多能干细胞库将对干细胞疗法用于修复脑和脊髓损伤、糖尿病、心力衰竭、视网膜病变的治疗应用至关重要，并将进一步使目前无法进行的一系列治疗干预成为可能。公共卫生相关性：多能(未分化)干细胞具有成为人体内几乎任何类型细胞的能力，因此，原则上可以用来取代传统上被认为不具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，要实施这些疗法，必须有能力识别、分离和增殖多能干细胞群体。我们已经成功地在无细胞系统中生长ESCs，通过添加一种单一的试剂来激活来自饲养细胞的ESCs条件培养液表面新发现的生长因子受体。

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.