White matter restoration and functional recovery after experimental stroke

实验性卒中后白质恢复和功能恢复

• 批准号: 9054320
• 负责人: Jun Chen
• 金额: $ 33.69万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-15 至 2020-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9054320
• 关键词: Action Potentials; Acute; Adult; Alteplase; Amino Acid Substitution; Anti-Inflammatory Agents; Anti-inflammatory; Antioxidants; Axon; Behavior; Binding; Blood - brain barrier anatomy; Brain; Cell Differentiation process; Cerebral Ischemia; Cerebral hemisphere hemorrhage; Clinical; Coculture Techniques; Cognitive deficits; Corpus Callosum; Data; Demyelinations; Distal; Dose; Epidermal Growth Factor Receptor; External Capsule; FDA approved; Failure; Fibrinolytic Agents; Generations; Genes; Human; Infarction; Injury; Intervention; Intranasal Administration; Intraventricular Infusion; Ischemic Stroke; Knockout Mice; Lead; Mediating; Membrane; Middle Cerebral Artery Occlusion; Modeling; Mus; Myelin; Myelin Sheath; Myelinated nerve fiber; Nervous System Physiology; Neurites; Neurologic; Neurological outcome; Neurons; Oligodendroglia; Patients; Peptide Hydrolases; Peroxisome Proliferator-Activated Receptors; Play; Prevention therapy; Process; Recovery; Recovery of Function; Regenerative response; Research; Risk; Rodent Model; Role; Serine Protease; Stroke; System; Testing; Therapeutic; Time; aged; axonal sprouting; cognitive testing; deprivation; disability; improved; in vivo; injured; mutant; myelination; neurological recovery; neurorestoration; neurotransmission; novel; oligodendrocyte precursor; overexpression; post stroke; precursor cell; public health relevance; receptor; remyelination; repaired; restoration; stroke therapy; thrombolysis; white matter; white matter injury; young adult

 DESCRIPTION (provided by applicant): White matter (WM) injury, characterized by demyelination and loss of axonal integrity, is an important cause of long-term sensorimotor and cognitive deficits after stroke. WM repair, including axonal regrowth, oligodendrogenesis and the myelination of demyelinated or newly generated axons, would help rebuild neuronal connectivity and reestablish axonal signal conduction. Unfortunately, the adult brain has limited capacity for remyelination, at least in part due to the failure of differentiation of oligodendrocyte precursor cells (OPCs) into mature, myelinating oligodendrocytes (OLs). Thus, interventions that promote OPC differentiation may facilitate axonal remyelination, WM repair and long-term neurological recovery in stroke patients. Human recombinant tissue plasminogen activator (tPA) is the only FDA approved drug for the thrombolytic treatment of ischemic stroke. However, recent research has discovered various neuroprotective effects by tPA that are independent of its thrombolytic activity. Moreover, intranasal administration of tPA improves functional recovery and promotes axonal sprouting after stroke. Currently, the use of tPA is limited to the first 4.5 hr after the oset of stroke, as beyond this time window it tremendously increases the risk of intracerebral hemorrhage (ICH) via BBB damage. This proposal will investigate the efficacy of tPAm, a mutant form of tPA that lacks thrombolytic activity (thus would not induce ICH), in rodent models of ischemic stroke. We have found in primary cultures that tPAm potently promotes the differentiation of OPCs into mature OLs. This effect of tPAm depends on its activation of PPAR, a master transcriptional factor that regulates cell differentiation and possesses antioxidant and anti-inflammatory functions. In vivo studies suggest that lack of endogenous tPA exacerbates functional deficits and WM injury up to 35 days after distal MCAO. In contrast, tPAm administration 6 hr after transient MCAO improved long-term neurological behavior and WM integrity. Our results suggest that tPAm enhances post-stroke WM integrity, at least in part, by promoting OPC differentiation and axonal myelination. This proposal will investigate the novel WM repair-enhancing role of tPAm and the underlying mechanisms. We will test the following overarching hypothesis: Treatment with protease-inactive tPAm facilitates WM repair and long-term neurological recovery after stroke, at least in part by promoting OPC differentiation and axonal myelination through PPAR. Both young adult and aged mice will be tested. Three Specific Aims are proposed. Aim 1: Determine whether post-stroke treatment with the protease-inactive tPAm enhances WM integrity and promotes long-term neurological recovery. Aim 2: Test the hypothesis that tPAm induces OPC differentiation/maturation and promotes axonal myelination via PPAR activation. Primary OPCs and a neuron-OPC co-culture system will be applied to test this hypothesis. Aim 3: Test the hypothesis that tPAm-induced OPC differentiation and axonal myelination/remyelination are essential for its beneficial effects on WM integrity and long-term neurological recovery after stroke.

 描述（由申请人提供）：白质（WM）损伤，以脱髓鞘和轴突完整性丧失为特征，是中风后长期感觉运动和认知缺陷的重要原因，包括轴突再生、少突胶质细胞生成和髓鞘形成。脱髓鞘或新生成的轴突将有助于重建神经连接并重新建立轴突信号传导，不幸的是，成人大脑的髓鞘再生能力有限，至少在这种情况下。部分原因是少突胶质细胞前体细胞 (OPC) 无法分化为成熟的髓鞘少突胶质细胞 (OL)。因此，促进 OPC 分化的干预措施可能会促进中风患者的轴突髓鞘再生、WM 修复和长期神经功能恢复。纤溶酶原激活剂 (tPA) 是 FDA 唯一批准用于溶栓治疗缺血性中风的药物。然而，最近的研究发现 tPA 具有多种神经保护作用。此外，tPA 的鼻内给药可改善中风后的功能恢复并促进轴突萌发。目前，tPA 的使用仅限于中风发作后的前 4.5 小时内，超过此时间窗口后，效果会显着降低。通过 BBB 损伤增加脑出血 (ICH) 的风险 该提案将研究 tPAm 的功效，tPAm 是一种缺乏溶栓活性的 tPA 突变形式。 （因此不会诱发 ICH），在缺血性中风的啮齿动物模型中，我们在原代培养物中发现 tPAm 有效促进 OPC 分化为成熟 OL，tPAm 的这种作用取决于其对 PPAR（一种调节主要转录因子）的激活。体内研究表明，缺乏内源性 tPA 会加剧远端 MCAO 后 35 天的功能缺陷和 WM 损伤。相比之下，短暂 MCAO 后 6 小时施用 tPAm 可改善长期神经行为和 WM 完整性，我们的结果表明，tPAm 至少部分通过促进 OPC 分化和轴突髓鞘形成来增强中风后 WM 完整性。 tPAm 的 WM 修复增强作用及其潜在机制我们将检验以下总体假设：使用蛋白酶失活的 tPAm 治疗可促进 WM 修复和长期神经功能。中风后的恢复，至少部分是通过 PPAR 促进 OPC 分化和轴突髓鞘形成，将测试年轻成年和老年小鼠的三个具体目标：确定使用蛋白酶失活的 tPAm 进行中风后治疗是否会增强。目标 2：检验 tPAm 诱导 OPC 分化/成熟并通过 PPAR 促进轴突髓鞘形成的假设。目标 3：测试 tPAm 诱导的 OPC 分化和轴突髓鞘形成/髓鞘再生对其对 WM 完整性和长期影响至关重要的假设。中风后的长期神经功能恢复。