Stem Cells and Ischemic Brain Injury

干细胞和缺血性脑损伤

• 批准号: 6540367
• 负责人: WALTER C LOW
• 金额: $ 33.41万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6540367
• 关键词: behavior test; brain derived neurotrophic factor; brain injury; cell differentiation; cerebral ischemia /hypoxia; clinical research; fibroblast growth factor; functional ability; green fluorescent proteins; human subject; nervous system disorder therapy; neural plasticity; neurosurgery; neurotrophic factors; nonhuman therapy evaluation; phenotype; spontaneous hypertensive rat; stem cell transplantation; stem cells; stroke; stroke therapy; tissue /cell culture

Studies of bone marrow cells have shown that they can restore neurologic function when transplanted into animals with ischemic brain injury. Recently, our laboratories have isolated a specific multi-potent stem cell population from human bone marrow that is capable of differentiating into neurons, astrocytes, and oligodendroglia in vitro under appropriate culture conditions. We postulate that these bone marrow-derived stem cells can provide an autologous source of donor cells for transplantation and repair in conditions of ischemic brain injury and stroke. In Specific Aim 1 we will determine the neural phenotypes generated from bone marrow-derived human stem cells when transplanted into the brain of spontaneously hypertensive rats. Human stem cells will be transduced to express eGFP to label the donor cells. Bone marrow-derived stem cells will then be transplanted into the striatum, hippocampal formation, or sensorimotor cortex. At various time periods after transplantation, brain tissue from host rats will be studied to identify presence of eGFP labeled cells. eGFP labeled cells will also be examined to determine whether they develop into neurons, glial cells, and/or oligodendroglia. Site-specific differentiation will also be evaluated to determine whether grafted neurons also co-express neurotransmitter markers that are characteristic of neurons that found in the striatum, hippocampus, and cortex. In Specific Aim 2 we will determine the efficacy of transplanted bone-marrow stem cells in ameliorating neurologic deficits associated with ischemic brain injury. The middle cerebral artery will be occluded unilaterally by ligation distal to the branching striatal vessels. This occlusion produces a discrete ischemic lesion of the cortex and results in permanent sensory and motor deficits in the forelimb contralateral to the side of injury. One week after the ischemic event animals will receive transplants of bone marrow-derived stem cells into regions of the neocortex surrounding the area of injury. In preliminary studies we have found that these transplants are capable of ameliorating sensorimotor deficits. The extent of the functional recovery will be assessed over time using a battery of behavioral tests. Also as part of Specific Aim 2 we will determine the time window after ischemic brain injury for stem cell transplantation that will result in an amelioration of neurologic deficits. In these studies ischemic rats will receive transplants at various time periods after ischemic injury and assessed functionally over time using a defined set of sensory and motor tests. In Specific Aim 3 we will investigate possible mechanisms underlying bone marrow-graft induced recovery of neurologic function. Possible mechanisms include trophic effects on neural stem cells of the host brain, the induction of growth factor release by host brain cells, and the reorganization of host fiber connections. The results of these studies will provide information regarding the efficacy of using specific bone marrow-derived stem cells as an autologous source of cells for transplantation in ischemic brain injury, and information regarding possible mechanisms of graft-induced neural plasticity.

对骨髓细胞的研究表明，将它们移植到脑缺血损伤的动物体内，可以恢复神经功能。最近，我们的实验室从人的骨髓中分离出了一种特殊的多潜能干细胞群体，在适当的培养条件下，它能够在体外分化为神经元、星形胶质细胞和少突胶质细胞。我们推测，这些骨髓来源的干细胞可以为缺血性脑损伤和中风条件下的移植和修复提供自体供体细胞来源。在具体目标1中，我们将确定骨髓来源的人类干细胞移植到自发性高血压大鼠脑内时产生的神经表型。人体干细胞将被转导表达绿色荧光蛋白，以标记供体细胞。然后，骨髓来源的干细胞将被移植到纹状体、海马结构或感觉运动皮质。在移植后的不同时间段，将对宿主大鼠的脑组织进行研究，以确定是否存在EGFP标记的细胞。还将检查EGFP标记的细胞，以确定它们是否发育为神经元、神经胶质细胞和/或少突胶质细胞。还将评估特定部位的分化，以确定移植的神经元是否也共表达纹状体、海马体和皮质中发现的神经元特有的神经递质标志物。在特定的目标2中，我们将确定移植的骨髓干细胞在改善与缺血性脑损伤相关的神经功能缺陷方面的效果。大脑中动脉将通过结扎分支纹状体血管远端而被单侧闭塞。这种闭塞导致大脑皮质离散的缺血性损伤，并导致损伤侧对侧前肢永久性的感觉和运动障碍。在缺血事件发生一周后，动物将接受骨髓来源的干细胞移植到损伤区域周围的新皮质区域。在初步研究中，我们发现这些移植能够改善感觉运动缺陷。随着时间的推移，将使用一系列行为测试来评估功能恢复的程度。此外，作为特定目标2的一部分，我们将确定缺血性脑损伤后干细胞移植的时间窗口，这将导致神经功能缺陷的改善。在这些研究中，缺血大鼠将在缺血损伤后的不同时间段接受移植，并使用一套明确的感觉和运动测试来评估一段时间的功能。在特定的目标3中，我们将研究骨髓移植导致神经功能恢复的可能机制。可能的机制包括对宿主大脑的神经干细胞的营养作用，宿主脑细胞诱导生长因子的释放，以及宿主纤维连接的重组。这些研究的结果将提供有关使用特定的骨髓来源干细胞作为自体细胞来源用于移植治疗缺血性脑损伤的有效性的信息，以及关于移植物诱导的神经可塑性的可能机制的信息。