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，当移植到缺血性脑损伤的动物体内时，它们可以恢复神经功能。 最近，我们的实验室已经从人骨髓中分离出一种特定的多能干细胞群，该细胞群能够在适当的培养条件下在体外分化为神经元、星形胶质细胞和少突胶质细胞。 我们假设这些骨髓源性干细胞可以为缺血性脑损伤和中风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干细胞移植到自发性高血压大鼠脑中时产生的神经表型。 人干细胞将被转导以表达eGFP来标记供体细胞。 然后将骨髓来源的干细胞移植到纹状体、海马结构或感觉运动皮质中。 在移植后的不同时间段，将研究来自宿主大鼠的脑组织以鉴定eGFP标记细胞的存在。 还将检查eGFP标记的细胞以确定它们是否发育成神经元、神经胶质细胞和/或少突胶质细胞。 还将评价位点特异性分化以确定移植的神经元是否也共表达神经递质标志物，所述神经递质标志物是在纹状体、海马和皮质中发现的神经元的特征。 在具体目标2中，我们将确定移植骨髓干细胞在改善缺血性脑损伤相关神经功能缺损方面的疗效。 通过结扎纹状体血管分支远端，单侧闭塞大脑中动脉。 这种闭塞产生离散的缺血性损伤的皮层和结果在永久性的感觉和运动缺陷的前肢对侧的伤害。 缺血事件后一周，动物将接受骨髓源性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。将使用一系列行为测试评估功能恢复的程度。 同样作为特定目标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，这将导致神经功能缺损的改善。 在这些研究中，缺血性大鼠将在缺血性损伤后的不同时间段接受移植，并使用一组定义的感觉和运动测试随时间推移进行功能评估。 在具体目标3中，我们将研究骨髓移植诱导神经功能恢复的可能机制。 可能的机制包括对宿主脑的神经干细胞的营养作用，诱导宿主脑细胞释放生长因子，以及宿主纤维连接的重组。 这些研究的结果将提供关于使用特定的骨髓源性干细胞作为缺血性脑损伤中移植的自体细胞来源的功效的信息，以及关于移植物诱导的神经可塑性的可能机制的信息。