摘要:近年來内皮前驅細胞(Endothelial progenitor cell, EPC )已被認為是心血管疾病和内皮功 能的重要生物標誌之一,與心血管系統之灌注有密切關係。然而EPC與腦部灌注的關係則仍 不清楚。本實驗室在科技部先前補助的整合計晝研究下,發現EPC在好發於東方兒童,會引 起腦缺血性中風的腦血管毛毛樣病(moyamoya disease, MMD)有重要的變化,包括周邊血液的 EPC數目異常增加,而且在病童接受間接血管吻合術後血管新生的1至6個月中,EPC的數 目更形增加,而與EPC相關的因子如VEGF、SDF1、BDNF也都有增加的情形。顯示EPC與 腦灌注不足息息以及血管新生相關,只是詳細機轉與其臨床應用價值仍不清楚。成人腦部灌 注不足的疾病,常見的有顧内動脈粥樣狹窄病變(Intracranial atherosclerotic steno-occlusive disease, ICASD)、腦血管毛毛樣現象,EPC所扮演的角色值得研究。EDAS (encephaloduroarteriosynangiosis)與 EMS (encephalomyosynangiosis)等間接的血管吻合手 術方式因為安全、有效,自1970年代開始便被用於兒童腦血管毛毛樣病的治療。近年來這些 間接血管吻合術也逐漸被用在成人腦灌注不足之治療。本院在過去三年也嘗試應用間接血管 吻合術治療成人腦血管毛毛樣病患者。追蹤結果顯示,九成左右的患者可以達到滿意的血管 新生效果。與直接的顧内外血管吻合手術不同的是,間接血管吻合術是藉由血管新生的作用, 由帶入顱内的組織長入新的侧枝循環。我們的研究顯示,灌注不足的腦方能引發良好的血管 新生,而此血管新生過程在術後約2周開始發生,在6周至3個月到達巔峰,這段期間的生 物基礎值得進一步研究。本計晝為一整合臨床與動物模型的研究,選擇臨床上成人腦灌注不足的重要課題,進行 間接血管吻合術手術前後與EPC相關的血管新生研究,並藉由動物腦缺血模型去驗證。我們 結紮大鼠雙侧内頸動脈建立慢性腦灌注不足的動物模型,再以植入顳肌的方式建立大鼠的 EMS血管吻合模型來進行血管新生的研究。除了測量新生血管的密度、血流量與腦組織氧分 壓,我們還將透過添加與血管新生相關的拮抗劑或興奮劑在EMS的黏著劑TISSEEL内,來 影響血管新生;並計晝直接將EPC注射入顳肌,或以靜注方式來操縱血管生成,以區分EPC 是經由paracrine或endocrine的機轉來影響血管新生過程,這對未來的臨床應用十分重要。此 外,我們將進一步研究EPC相關的neurotrophic激素的作用,探討大鼠EMS術後neuron stem cell (NSC)在subventricular zone的增殖能力,並將EMS後的腦脊液與NSC共同培養,進一步 探討相關因子激發NSC的能力。這個創新動物模型的建立,除了可用來研究間接血管吻合術的血管再生機轉;並可藉由 控制内皮前趨細胞及其相關因子來影響血管新生,希望未來可以應用到臨床的治療與診斷, 幫助各種腦灌注不足的病人。
Abstract: Circulating endothelial progenitor cells (EPCs), which derive from bone marrow, have been suggested to be a marker of cardiovascular risk and endothelial function. EPCs have been implicated in neoangiogenesis after tissue ischemia has occurred and EPCs are capable of proliferating and differentiating into endothelial cells for vascular regeneration. However, the role of EPC in cerebral hypoperfusion was not clear. Our previous study showed that the EPC numbers increased abnormally in pediatric patients with moyamoya disease (MMD), a disease commonly causes cerebral hypoperfusion or even cerebral infarction in children. We also demonstrated that the EPC numbers further increase 1 to 6 months after indirect revascularization surgery. The levels of VEGF, SDF1, and BDNF also increased in the postoperative period. It suggests that EPC plays an important role in cerebral hypoperfusion and the vasculogenesis, though the mechanism needs further studies.Indirect revascularization using superficial temporal artery, dura, temporalis muscle, or pericranium has been used in pediatric moyamoya disease since 1970s. Encephaloduroarteriosynangiosis (EDAS), encephalomyosynangiosis (EMS), and encephalopericraniosynangiosis (EPS) are three commonly used indirect revascularization procedures that induced new collateral formation to the ischemic brains in children. The new vessel formation starts to develop 2 weeks after indirect revascularization and reaches the plateau 6 months after surgery. Due to the safety and effectiveness, indirect revascularization has been used in adult patients with moyamoya disease and gradually used to treat selected patients with intracranial atherosclerotic steno-occlusive disease (ICASD) or moyamoya phenomenon in recent years. The role of EPCs and mechanism in adult patients with cerebral hypoperfusion is still not known.This project combines clinical and animal studies to investigate the role of EPC and its relative factors in vasculogenesis that occurs in cerebral hypoperfusion before and after indirect vascularization. Clinically, we plan to recruit patients with ICASD or moyamoya phenomenon, which are the common causes of cerebral ischemia in adults, for study. To further investigate the mechanism of vasculogenesis after indirect revascularization in chronic hypoperfusion brain, we try to set up a new animal of indirect revascularization. In preliminary study, we have successfully established a rat model of cerebral ischemia by ligating bilateral carotid arteries, and revascularized the ischemic cerebral hemisphere by EMS.To study the mechanism of the vasculogenesis induced by EMS, we plan to apply agonists and antagonists of various trophic factors related to EPC into the adhesive fibrin sealant, TISSEEL, which was applied between the temporalis flap and the cerebral cortex during EMS procedure. In addition, we will apply EPC to the animals by intravenous or local muscular injection to see whether the EPC induces the vasculogenesis via endocrine or paracrine effect? It is hoped that it may be implicated clinically in the future. Finally, we will study the effect of EMS on the proliferation of neuronal stem cell (NSC) by immunostaining and co-culture of the CSF and NSC.