微氣泡配合超音波提升抗血管腫瘤治療

Improving Anti-Vascular Tumor Therapy by Using Ultrasound with Microbubbles

王子嘉(Tzu-Chia Wang)

指導教授 ： 葉秩光

國立清華大學/原子科學院/生醫工程與環境科學系/碩士(2017年)

摘要

抗血管治療是以阻斷腫瘤不成熟血管，使氧氣與養分無法運輸至腫瘤組織內，進而達到抑制腫瘤的治療效果。然若以現行之抗血管治療，則會因腫瘤周圍血管多為成熟且具有穩定結構使其無法被治療，產生存活邊緣效應，造成局部腫瘤復發。而以超音波刺激微氣泡產生之慣性穴蝕效應可造成血管破裂，達到抗血管之療效。由文獻中得知血管破裂效率會與慣性穴蝕效應劑量成正比，因此若藉由調控超音波參數提高慣性穴蝕效應劑量，則可能擊破腫瘤周圍血管。此外，若再搭配化療藥物，除了可使其累積在腫瘤周圍組織中，補償抗血管治療對腫瘤周圍產生之抗性，也可使其經由破裂血管滲透至腫瘤組織提升藥物滲透量。故本研究藉由調控超音波參數提升抗血管治療效率和藥物滲透，來提高整體療效。本研究使用自製之微氣泡(1.12±0.08 µm)進行體外慣性穴蝕效應劑量之測量，用以評估與抗血管效應之相關性。並以載有窗型觀測腔之小鼠透過血管破裂效率和藥物滲透量來評估適當超音波參數，以應用後續實質腫瘤之治療。在實質腫瘤治療之部分，以2 MHz、1000週期數、2 Hz脈衝重複頻率和7 MPa聲壓並注射2×107微氣泡進行超音波照射，同時搭配自製之微脂體阿黴素(160 µg/mouse)進行結合治療。透過窗型觀測腔實驗，發現以3、5、7和9 MPa的聲壓照射時，血管直徑介於21-30 µm分別有0、33、50和50%的機率被擊破，並且血管破裂大小與慣性穴蝕效應劑量之相關指數為0.931，因此選用7 MPa進行實質腫瘤之結合治療。在療效部分，腫瘤中心和周圍血流灌注分別下降至27±3%和27±4% (p>0.05)，而血管密度則分別下至23±14%和24±5% (p>0.05)。由此結果可知結合治療可均勻地治療腫瘤中心和周圍，並相較於控制組有74±2.4%的腫瘤生長抑制效果(p<0.05)。因此，本研究證實了使用適當之超音波參數，能有效提升血管破裂效率和藥物滲透，減少存活邊緣效應並提升活體存活率。

關鍵字

微氣泡 ； 微脂體阿黴素 ； 超音波治療 ； 抗血管治療 ； 結合治療

並列摘要

Anti-vascular therapy disrupts tumor immature vessels to restrict oxygen and nutrient transport for tumor growth inhibition. However, tumor peripheral vessels with mature and stable structure show treatment resistance in current anti-vascular therapy, called the viable rim effect, to induce local tumor recurrence. Ultrasound stimulated microbubble can damage vascular endothelial cells to accomplish anti-vascular therapy by microbubble inertial cavitation. Since previous studies reported that the efficiency of vascular disruption was proportional to the microbubble inertial cavitation dose, which provided a potential way to disrupt tumor peripheral vessels by regulating ultrasound parameters. Furthermore, chemotherapy was applied to compensate the treatment resistance of anti-vascular therapy via drug accumulation in tumor periphery, the disrupted tumor vessels can also improve drug penetration in tumor center. Therefore, our study investigated the efficiency of anti-vascular effect and drug penetration to improve therapeutic efficacy by regulating ultrasound stimulated microbubbles. The in vitro inertial cavitation dose of home-made microbubbles (1.12±0.08 µm) was measured to evaluate the correlation in anti-vascular effect. Window chamber mice model was applied to define the optimal ultrasound parameters by assessing the efficiency of vascular disruption and drug penetration. The optimal parameters of ultrasound (2-MHz, 1000-cycle, pulse repetition frequency of 2 Hz, 7 MPa, and 2x107 microbubbles/mouse) and liposomal-doxorubicin (160 µg/mouse) were applied for combination therapy in solid tumor model. The efficiency of vascular disruption at 3, 5, 7, and 9 MPa showed 0, 33, 50, and 50% at the vessel size of 21-30 µm. The correlation coefficient was 0.931 between the in vitro inertial cavitation dose of microbubbles and disrupted vessel size. Comparison the treatment efficacy in tumor center and periphery, blood perfusion was reduced to 27±3% and 27±4% (p>0.05), and vessel density was decreased to 23±14% and 24±5% (p>0.05). The uniform treatment in both tumor center and periphery by combination therapy inhibited 74±2.4% of tumor growth relative to the control group (p<0.05). Therefore, our study confirmed that regulating ultrasound parameters can improve the efficiency of anti-vascular therapy and drug penetration to reduce the viable rim effect and inhibit tumor growth.

並列關鍵字

Microbubble ； Liposomal-doxorubicin ； Ultrasound ； Anti-vascular therapy ； Combination therapy

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