MSCs Induce Brain Plasticity via tPA

描述（由申请人提供）：基于细胞的疗法在减少与中风相关的神经功能缺陷方面显示出巨大的希望。这些疗法中最有效的一种是骨髓基质细胞（MSCs），它已被证明具有高度的神经修复作用。在这个应用中，我们将研究MSCs产生这种神经修复作用的机制。我们的初步数据强烈表明，骨髓间充质干细胞治疗脑卒中促进脑神经突重塑。我们提出，中风后给予MSCs，可激活实质细胞内的组织纤溶酶原激活剂（tPA）， tPA介导神经突重塑，从而改善神经功能。因此，我们对以下三个假设进行了验证：假设1:a) MSCs增加实质细胞中tPA的活性；b) tPA活性增加增加神经突起重塑；c)神经突重塑增加有助于脑卒中后功能预后的改善。假设2:a) MSCs通过Shh信号通路上调星形胶质细胞、神经元和内皮细胞的tPA活性；b) MSCs通过Shh信号通路下调TGF-¿1/PAI-1，从而增加tPA活性。假设3:MSCs增加tPA活性通过纤溶蛋白依赖的前神经营养因子的蛋白水解裂解促进神经突重塑：前神经生长因子（pro-NGF）转化为NGF，前脑源性神经营养因子（pro-BDNF）转化为BDNF。这些假设分析了外源性MSCs和内源性实质细胞的相互作用及其对脑卒中后tPA活性、神经突重塑和神经功能的影响。我们的研究采用转基因tPA-/-， Plg-/-小鼠以及我们实验室一系列新颖和完善的实验技术。据我们所知，我们的工作是第一个研究tPA活性作为一个关键的统一因素，以扩大外源性细胞在中枢神经系统中的有益作用。这个项目是一个连贯的和高度相互交织的努力，以阐明分子和细胞途径，受伤的大脑可以通过细胞治疗重塑。我们的最终目标是描述细胞疗法在中风恢复性治疗中的机制基础。我们的研究对所有神经系统疾病和损伤的治疗意义是显而易见的。

DESCRIPTION (provided by applicant): Cell-based therapies have shown enormous promise in reducing neurological deficits associated with stroke. One of the most effective of these therapies is bone marrow stromal cells (MSCs), that has been demonstrated to be highly neurorestorative. In this application, we will investigate the mechanisms by which MSCs produce this neurorestorative effect. Our preliminary data strongly indicate that MSC treatment of stroke promotes neurite remodeling of brain. We propose that when administered after stroke, MSCs activate tissue plasminogen activator (tPA) within parenchymal cells, and tPA mediates neurite remodeling leading to improvement in neurological function. Therefore, the following three hypotheses are tested: Hypothesis 1: a) MSCs increase tPA activity in parenchymal cells; b) Increased tPA activity increases neurite remodeling; c) Increased neurite remodeling contributes to improvement of functional outcome after stroke. Hypothesis 2: a) MSCs up-regulate tPA activity in astrocytes, neurons and endothelial cells via the Shh signaling pathway; b) MSCs down-regulate TGF-¿1/PAI-1 via the Shh signaling pathway and thereby increase tPA activity. Hypothesis 3: tPA activity increased by MSCs promotes neurite remodeling via plasmin-dependent proteolytic cleavage of pro-neurotrophins: pro-nerve growth factor (pro-NGF) to NGF, pro-brain derived neurotrophic factor (pro-BDNF) to BDNF These hypotheses dissect the interactions of exogenous MSCs and endogenous parenchymal cells and their affect on tPA activity, neurite remodeling and neurological function after stroke. Our studies employ genetically modified tPA-/-, Plg-/-mice as well as an array of novel and well-established experimental techniques in our laboratory. To our knowledge, our work is the first to investigate tPA activity as a key unifying factor to amplify beneficial actions of exogenous cells in the CNS. This project is a coherent and highly interwoven effort to elucidate the molecular and cellular pathways by which injured brain can be remodeled by cell-based therapies. Our ultimate goal is to delineate the mechanistic underpinnings of cell-based therapy in the restorative treatment of stroke. The therapeutic implications of our studies for all neurological disease and injury are evident. PUBLIC HEALTH RELEVANCE: Our study will provide essential insight into how the injured brain is remodeled and neurological function improved using a cell-based therapy. Restorative therapy using exogenously administered cells is not limited by a narrow therapeutic window and can be administered to all stroke patients. Our goal to identify how these administered cells interact with the endogenous brain cells will likely bring to fruition restorative cell-based therapy for the treatment of stroke and neural injury.