腫瘤的生長速度非常快，有時血管的新生速度會跟不上腫瘤體積的增加，血液便沒辦法充分流至腫瘤內部，進行有效的氣體交換，使得腫瘤內部容易產生缺氧的區塊。而缺氧區的癌細胞具有極高的變異性，能透過各種機制來調整、隱蔽自己，使其難以被免疫細胞所察覺，或阻斷由胞殺性T細胞所引發的細胞溶解路徑，以增加癌細胞本身的存活能力，這也增加了要徹底根除癌細胞 的難度。
現今免疫治療多採用施打單一抗體的方式，用以針對特定抗原誘發強烈免疫反應。而隨著醫療的發展，近來在免疫治療的研究上，多數都採取結合多種抗原、佐劑一同施打的方式，同時加入anti PD-1等免疫檢查點抑制劑的施打，以防止腫瘤細胞自我隱蔽的機制。在本研究中，我們將過氧化鈣和奈米鉑金屬包覆於具有疏水性的聚乳酸-甘醇酸(poly lactic-co-glycolic acid, PLGA)載體內，利用過氧化鈣與水溶液反應產生過氧化氫，再透由奈米鉑的催化能力使過氧化氫轉換為氧氣路徑，以期透過這個載體產生氧氣。載體所提供的氧氣，可供給在缺氧環境中的細胞足夠的氧氣，改善癌細胞因缺氧而產生的免疫抑制。我們也期望在動物實驗中，將載體打入腫瘤，能藉由其產生的氧氣改善腫瘤內部的缺氧環境，進而去減緩缺氧區塊對免疫細胞的排斥。

In the absence of adequate oxygen, cancer cells that are grown in hypoxic solid tumors developed resistance to lymphocyte-mediated lysis, thus reducing the effectiveness of cancer immunotherapy. We therefore hypothesize that regional oxygen treatment by an injectable oxygen-producing microparticle system may reverse tumor hypoxia and enhance the efficacy of cancer immunotherapy in a highly site-specific manner, without raising systemic oxygen levels. The oxygen-producing microparticle system are prepared by encapsulating calcium peroxide (CaO2) and platinum nanoparticles (Pt NPs) into poly(D,L-lactic-co-glycolic acid) (PLGA) microparticles (MPs) using a microfluidic device, and then are harvested by filtration and then air-dried. Under physiological condition, the CaO2 that is encapsulated in the PLGA MPs reacts with the interstitial medium to produce calcium hydroxide [Ca(OH)2] and hydrogen peroxide (H2O2). The Pt NPs encapsulated in the PLGA MPs then catalyzes the decomposition of H2O2 to oxygen and water, ultimately allaying the hypoxia-induced immune suppression. The as-prepared microspheres are capable of sustainably release oxygen over 16 hours. In the in vitro study, the oxygen-producing microparticle system can reduce the level of HIF- protein in CT26 colon carcinoma under low oxygen tension (1% O2), resulting in the inhibition of hypoxia-induced autophagy, which can promote tumor cell resistance to lymphocyte-mediated lysis. These results suggest that the oxygen-producing microparticle system that were prepared herein may serve as an in situ oxygen-generating reservoir in relieving hypoxia in solid tumors

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