摘要:分子及活體細胞追蹤造影技術在臨床診斷與基礎醫學研究上扮演著日益重要的角色。本研究目的為發展生醫分子及活體細胞追蹤之磁振造影技術,並研究其在早期偵測並評估肺癌細胞小鼠模式之腫瘤血管新生型態功能及其轉移。主要內容為發展動態顯影磁振造影之血管新生評估技術、開發對細胞分子表現特異性鑑別之奈米磁振顯影劑、並且利用高溫超導射頻線圈及平行影像重建法來達到高訊雜比及高效率之磁振造影技術,用來研究肺癌細胞與肺臟轉移小鼠模式。結合上述技術之開發則可更進一步提供病灶分子病理資訊並設計多功能甚或智慧型藥劑,使醫師得以即時知道用藥之效能與投遞分布情形以最佳化治療策略。
此計畫針對肺癌之疾病模式作為主要之疾病研究標的,其主因為肺癌在台灣及其他工業化國家最常見之癌症死亡原因之一,也是極重要之公衛問題。此外,肺癌之臨床特徵為不易早期診斷,並常早期發生轉移,尤其是肺腺癌更常在疾病發現初期,即有遠處轉移之現象,並且常有手術後復發之情況。就目前的治療成效,非小細胞肺癌對放射線治療及化學治療之反應也較差。因此研究發展早期診斷肺癌、早期偵測肺癌轉移、評估腫瘤血管新生能力以及監測肺癌治療反應之新方法,即成為刻不容緩之課題。於此,本團隊已建立VEGF(vascular permeability factors)與EGFR超表現或低表現之鼠肺癌活體模型之標準化誘導程序,可快速以正位手術移植法重現,將作為本研究標的。
子計畫一中動態顯影之核磁共振照影技術的平台發展可以結合藥物動力的模式提供肺癌之動物疾病模式之血管新生評估,亦可與組織病理的診斷結果相互比較。於子計畫二針對細胞分子表現特異性鑑別之奈米磁振顯影劑的發展平台部份,可藉由測試修改奈米粒徑及表面化學以改良並強化其顯影效果並合成可控制均勻大小之正(胺基)或負電荷(梭基)表面之氧化鐵奈米粒作為負顯影劑之核心部分;根據過去的文獻報導,EFGR(Epidermal growth factor receptor)為一腫瘤生長激素表面受器,其功能可被抗EGFR抗體抑制(本團隊已可自融合瘤量產並純化此抗體),因此未來將進一步連結抗腫瘤特異性表面抗原之單株抗體,如EGFR或其重組抗體,以作為融合標的投遞之導向器及攻擊武器於一體之雙功製劑。
此外,亦可藉由此一氧化鐵奈米測試同步強化間質負顯影背景與腫瘤正顯影下是否更能襯托出轉移之聚集微小病灶以增強其早期診斷鑑別力。為達以上目的,增強奈米粒子投遞效能,減少其肝肺脾臟之非特異吸附,團隊將測試既有之PEI及短鏈核酸等介面連結技術以達到生物隱形作用(biological stealth),亦將評估奈米交聯基因表現組合及抗癌藥之治療顯影一體雙功型製劑的效能,並建立以標準化程序執行奈米粒子之生物及血液相容性評估。
在磁振造影之分子影像擷取部份(子計畫三),此計畫將整合跨領域的磁振造影技術,包括擴散磁振造影、微灌流磁振造影及顯微磁振造影以建立一個宏觀且領先的磁振分子影像造影技術。此外,本團隊將發展出高效率改良式的高速成像序列及高溫超導射頻線圈造影技術並使用具有強梯度磁場的顯微造影線圈及平行影像技術及其重建演算法,藉以大幅提升影像敏感度、解析度、訊雜比、及取像速度。為了適用於活體動物實驗,本計畫將結合上述改良造影技術於3T (Tesla) 磁振造影系統以建立小鼠實驗技術平台。有了此一最佳化之小動物平台,將有助於研究奈米顆粒顯影劑的對比特性、建立適合於磁振照影對比強化的肺癌動物模型之造影平台、並評估動態顯影之核磁共振照影技術與合成之奈米顆粒顯影劑之體內生物分佈及標記之功效。
Abstract: Molecular and cell specific imaging play increasingly important roles in both clinical diagnosis and fundamental biomedical researches. In this study, we aim to develop a platform of dynamic contrast-enhanced (DCE) MRI and molecular MR imaging system that specifically recognizes cancer cells and exerts its therapeutic efficacy while enables real-time tracking of the drug distribution. This kind of system will provide not only valuable molecular pathological information but also real-time therapeutic efficacy evaluation for personalized healthcare treatment strategy.
Among various disease models, lung cancer is one of the most common causes of cancer-related death in Taiwan (top 2nd) as well as other industrialized nations. The prognosis of lung cancer is poor as compared with other malignancies. Therefore, the research for early diagnosis, early detection of metastasis, and tumor-associated angiogenesis process, and assessment of therapeutic response become more and more important for lung cancer diagnosis and treatment. IN this study, pulmonary tumor implantation animal models in mice with high and low VEGF (vascular permeability factors) and EFGR expression lung cancer cell carcinoma model were established by our team and will be used through the whole three years.
In subproject 1, using information of dynamic contrast-enhanced (DCE) MRI coupled with pharmacokinetic model, we can probe the in vivo angiogenesis of lung cancer and compare it with histopathologic angiogenesis findings. In subproject 2, there are evidences of non-invasive measurement of vascular permeability characteristics and apoptosis of tumor before the change of tumor size by using MRI with the information from apparent diffusion coefficient (ADC) and superparamagnetic iron oxide (SPIO) particles. For specifically recognized cancer cells, we have previously developed synthesis of iron oxide nanoparticles with excellent stability, biocompatibility, and interface for additional biochemical modifications. In this project, we will improve the synthesis and modifications of iron oxide nanoparticle to achieve better contrast and targeting effect. Furthermore, for combined molecular expression specific cancer targeting and therapy, bioconjugation of nanoparticles with anti-EGFR (Epidermal growth factor receptor) monoclonal antibody or specific recombinant ligand peptides will be performed, and the materials will be evaluated whether or not an increased signal contrast and hence high detection rate could be achieved for early detection of metastatic lesions.
To achieve high quality molecular MR imaging, in subproject 3, custom designed high temperature superconducting RF coil with strong imaging gradient insert with parallel acquisition will be designed to ensure excellent signal-to-noise ratio, high resolution, and fast acquisition for this study. Furthermore, this project will integrate multi-modality diffusion, perfusion and microscopic molecular imaging MR using smart contrast agent to provide a full-spectrum MR modality as the modern molecular imaging methodology. With these techniques, it will be very helpful to characterize the imaging contrast performance of the contrast-enhanced (DCE) MRI technology and the nanoparticle based agents, to establish the imaging platform for in vitro and in vivo disease models.