STUDIES OF ADULT BRAIN NEUROPOIESIS

描述（申请人提供）：中枢神经系统干细胞的归巢、维持和整合是神经生成和再生神经生物学新兴领域的新课题。干细胞可塑性的概念已经通过所谓的组织特异性干细胞被诱导成其他组织表型的不同例子得到了发展。这种改变组织特异性干细胞的命运，诱导转分化，已经在许多不同的生物测定中报道，使用各种细胞培养和体内条件和操作。本研究将比较成年啮齿动物大脑中持续神经源性（或“神经生成”）区域——室管膜下区（SEZ）及其吻侧迁移流（RMS）在神经化条件下的归巢、干细胞更新、命运控制和分化，该区域参与包括嗅球在内的前脑结构的持续再生。提出了三个具体目标，将使用体内和体外桥接生物测定法评估来自脑（多能星形细胞干细胞，或神经干细胞的“NSC”）和血液（“HSC”，造血干细胞）的两种候选干细胞群。Specific Aim 1将测试特定的细胞外基质分子（tenascin-C和硫酸软骨素蛋白聚糖）、候选整合素受体、细胞表面分子（cd15和CD9）、趋化因子及其受体（SDF-1/CXCR4）由这些细胞和SEZ/RMS表达，以促进干细胞的归巢、维持和整合。Aim 2将进一步验证这一点，通过使用敲除动物和针对这些候选归巢/整合因子的功能阻断抗体，研究NSC和HSC移植后这些分子在体内的可能作用。最后，Aim 3将通过对组织外植体-干细胞共植体的敏感形态学和电生理分析，验证NSC和HSC可以在前脑神经源性结构中功能整合的假设。在我们能够理解血细胞转变为脑细胞的潜力之前，有必要了解起始细胞群的干细胞程度，并阐明干细胞归巢、维持和整合到受损中枢神经系统回路中的因素。这是一个深刻的转分化例子，为当前的细胞替代疗法提供了许多替代方法。这里提出的研究也为神经和造血细胞的长期培养和整合提供了见解，并着眼于开发各种脑和血液疾病的治疗方法。

DESCRIPTION (provided by applicant): Homing, maintenance, and integration of stem cells in the central nervous system are rather new topics in emerging fields of neuropoiesis and regeneration neurobiology. The notion of stem cell plasticity has been advanced by different examples of so-called tissue specific stem cells being coaxed into other tissue phenotypes. This altering fate of tissue-specific stem cells, inducing transdifferentiation, has been reported in many different bioassays, using a variety of cell culture and in vivo conditions and manipulations. This proposal will compare homing, stem cell renewal, fate control and differentiation under neuralizing conditions in a persistently neurogenic (or "neuropoietic") region of the adult rodent brain - the subependymal zone (SEZ) and its rostral migratory stream (RMS) that is involved in continual repopulation of forebrain structures including the olfactory bulb. Three specific aims are proposed that will evaluate two candidate stem cell populations from brain (multipotent astrocytic stem cells, or "NSC" for neural stem cells) and blood ("HSC", hematopoietic stem cells) using in vivo and in vitro bridging bioassays. Specific Aim 1 will test the hypothesis that particular extracellular matrix molecules (tenascin-C and chondroitin sulfate proteoglycan), a candidate integrin receptor, cell surface molecules (CD 15 and CD9), and a chemokine and its receptor (SDF-1/CXCR4) are expressed by these cells and the SEZ/RMS to facilitate stem cell homing, maintenance and integration. Aim 2 will further test this, via studying the possible actions of these molecules in vivo following transplantation of NSC and HSC, using knockout animals and function blocking antibodies to these candidate homing/integration factors. Finally, Aim 3 will test the hypothesis that NSC and HSC can functionally integrate within forebrain neurogenic structures, using sensitive morphological and electrophysiological analyses of tissue explants - stem cell coplants. Before we can understand the potential of blood cells to become brain cells, a profound example of transdifferentiation that offers numerous alternative approaches to current cell replacement therapies, it is necessary to understand degrees of stemness of starting cell populations, and also elucidate factors involved in stem cell homing, maintenance, and integration to and within damaged CNS circuits. The studies proposed here also provide insights into long term culturing and integration of neuropoietic and hematopoietic cells, with an eye toward the development of therapeutics for a variety of brain and blood diseases.