摘要:神經細胞有神經元(Neuron)和神經膠細胞(Glia)兩大類細胞。神經元細胞屬神經系統構造和功能的基本單位,乃負責神經訊息的傳遞。而神經膠細胞種類繁多,數量遠大於神經元細胞,本身不具神經訊息傳遞功能,負責維持神經元構造、供應所需養分、調節環境恆定、保護或清除異物、協助神經元的生長發育、加速神經衝動的傳遞速率等功能。中風及腦血管相關疾病造成的死亡人數高居世界十大死因中的第二位(在台灣為第三位),也是造成長期失能最重要的疾病。因中風及腦血管相關疾病所造成的死亡、併發症、以及照護的需求,會造成龐大的社會成本。據統計,初次腦中風後之5 年內累積復發率為26.4%, 10 年內累積復發率為39.2%。目前對缺血性腦中風較有效的積極性臨床治療僅有血栓溶解術(thrombolysis),但此治療方法受限於較短的治療黃金期(三小時內)、以及腦出血之風險,所以在臨床上並無法廣泛性使用。因此,預防勝於治療,如何找出有效對於腦中風高危險群例如有高血壓、心臟病、高血脂、糖尿病等患者的預防或腦中風癒後患者復發(recurrence)防治是目前對缺血性腦中風防治的當務之急,也是非常重要的研究課題。另一方面,超音波目前在一般臨床醫學上的應用主要是作為診斷用的即時造影設備,或是作為侵入性治療的即時定位。近年來,超音波也被發現可以做為治療疾病的一種方法,其主要應用有兩個方面,一種是高強度聚焦式超音波(high-intensity focused ultrasound, HIFU),另一種是低強度脈衝式超音波(low-intensitypuled ultrasound, LIPUS)。高強度聚焦式超音波可引發熱效應,在人體組織中具有良好的穿透性,可以將能量傳至深層組織,可以造成聚焦區域溫度升高,燒灼破壞蛋白質或引起組織內細胞凋亡及傷害等,此種大能量的累積可以應用在腫瘤細胞的熱燒灼治療上。但是以上的治療方法只能利用高溫的熱治療來切除病灶發生的區域,可能無法達到完全治癒效果,通常對周圍的正常細胞也會有所影響。LIPUS 相較於HIFU,所造成傷害的可能性較低也可以恢復,所以應用的範圍也可更為廣泛。運用LIPUS 作為缺血性腦中風預防或復發防治是有其潛在意義與應用價值,但目前很缺乏相關之研究,這也是我們感興趣而要積極探討的課題。本計畫第一年研究成果(2016/08-2016/12)顯示預先施作LIPUS 可有效預防缺血性腦中風小鼠之病理及行為變化;細胞或動物模式也皆發現LIPUS 會有效促進腦原性神經營養因子(BDNF)產生(請詳見計畫書內容)。基於腦中風後之高復發率,對於缺血性腦中風之復發防治是重要的課題,我們希望能繼續完成當初的第二年計畫目標-缺血性腦中風復發防治。我們計畫於本年度申請計畫中完成下列之確切目標和研究重點(一年期計畫流程):1. 利用神經細胞(包括神經元及神經膠細胞)培養模式探討LIPUS 對於二次缺氧/再灌流傷害(模擬復發(再中風)情況)防治作用與可能作用機轉。2. 利用小鼠MCAO 缺血/再灌流動物模式進行二次缺血性腦中風(strokerecurrence)模式來模擬中風後再復發情形,進而探究LIPUS 是否對於缺血性腦中風復發有防治效果及可能之作用機轉。本計畫為一新的概念,利用非侵入性之診斷用途相當強度之LIPUS嘗試用於缺血性腦中風之復發(再中風)防治的研究,若細胞及動物模式實驗可以證明此方法對於治療二次缺血性腦中風的可能性,則未來進行臨床試驗或甚至應用於臨床治療上將是可預期或期待的。
Abstract: Nerve tissue is composed of neurons and glial cells. Neuron is the basic unit of structure andfunction in the nervous system and is responsible for nervous signaling transduction. Glial cells arebelonging to the supporting cells, which numbers are much larger than neurons. The functions ofglial cells contain: maintaining neuronal structure, supply the necessary nutrients, regulate theenvironment constant, protect or remove foreign bodies, assist the growth and development ofneurons, and accelerate the conduction rate of nerve impulses and so on. According to World HealthOrganization, stroke and cardiovascular disease are the second leading causes of death worldwide.Stroke occurs because of interruption of blood flow due to thrombosis. Patients with stroke willexperience sudden paralysis, loss of vision or death. Hypoxia/reperfusion (H/R) injury occurs whenthrombosis is removed. H/R injury can cause damage to brain cells through ATP depletion, reactiveoxygen species, inflammation or apoptosis. Moreover, the pooled cumulative risk of strokerecurrence has been reported to be 26.4% at 5 years and 39.2% at 10 years after initial stroke.Currently effective treatment for ischemic stroke is only thrombolysis, but this approach is limitedby the treatment timing and the risk of cerebral hemorrhage. Therefore, prevention is better thantreatment. How to find an effective method to prevent (1) the development of stroke in the patientswith high-risk for stroke such as hypertension, heart disease, hypercholesterolemia, and diabetes or(2) the development of stroke recurrence is urgent. On the other hand, ultrasound is widely used fordiagnostic medical imaging, and is a safe and effective modality to visualize pathological lesions inhuman body. In recent years, ultrasound has also been found to be used as a method for treating adisease, its main application has two aspects, one is a high intensity focused ultrasound formula(HIFU), and the other is a low-intensity pulsed ultrasound (LIPUS). HIFU can lead to thermaleffects style, with good penetration in human tissues, energy can be transferred to the deep tissue,the focus area can cause the temperature rises, burning causing damage to proteins or cellinjury/apoptosis within tissues. Accumulation of such large energy can be applied to the thermalcautery treatment of tumor cells. But the above method using high-temperature heat treatmentusually might damage the surrounding normal cells or tissues. LIPUS, as compared to HIFU, is lesslikely to cause harm and can be restored, so the range of applications can be more extensive.However, the preventive effects of LIPUS on ischemic stroke and stroke recurrence are still unclear.In the results of 1st year-project (2016/08-2016/12), we found that pre-treatment of LIPUS couldeffectively prevent the pathological and behavior changes in a cerebral ischemia/reperfusion strokemouse model; we also observed the significantly increased expression of brain-derived neurotrophicfactor (BDNF) in cultured nervous cells and stroke mice (detailed results shown in applied project).The aims of the 2nd year-project (the applied project of this year) are to investigate the preventiveeffects of LIPUS on stroke recurrence using cell and animal models. The goals and key points ofthis project are: 1. cellular models of recurrent ischemia/reperfusion in neuronal cells and glial cells:To investigate the preventive effects and possible mechanisms of LIPUS on recurrenthypoxia/reperfusion-induced neuronal and glial cell injuries; 2. a recurrent cerebralischemia/reperfusion mouse model: To investigate the effects and possible mechanisms of LIPUSon recurrent stroke-induced brain injuries. This project is a new concept. The non-invasive LIPUS,which intensity is in the range of diagnostic ultrasound, will be used to test its effects on ischemicstroke. If these cell and animal model experiments can prove that this method is work for theprevention of stroke recurrence, the clinical trials or even used in clinical application will beexpected or anticipated in the future.