【作者】 张岩；

【导师】 韩胜皓；

【作者基本信息】 吉林大学 ， 外科学， 2014， 博士

【摘要】 虽然肝癌病人最有效的治疗方法是手术切除，但如果肿瘤复发患者的长期生存是很差的。在早期肝癌局部复发的风险与原发肿瘤手术切缘的距离相关。在有效手术切除患者中39%已确定在手术切缘有残余的微小的肿瘤细胞，这表明局部复发来自手术切缘附近残留的隐匿性肿瘤细胞。因此为了防止肿瘤复发，对于恶性程度高的肿瘤往往同时进行放疗或化疗。基于这些原因，新辅助化疗和外部放射治疗有时优先于手术切除，通过用来缩小巨大的肿瘤和控制肿瘤的生长来为预计手术的患者的肿瘤“降级”。虽然放射治疗对于手术切除治疗来说有较低的5年生存率，但其可以用来治疗早期癌症和晚期前列腺癌、乳腺癌、肺癌或无法耐受手术切除患者的替代治疗。不幸的是，急性和长期毒性限制了这些局部治疗的疗效，并使其不能在所有的患者中成为常规的预防措施。由于全身静脉化疗对肿瘤没有明确的靶向性，故在肿瘤内部或临近组织很难达到有效的药物浓度。此外，在健康的组织内药物则经常聚集而达到很高的浓度，从而导致严重的副作用和限制性剂量毒性。由于高的材料成本、需要某些特殊专家（放疗和化疗肿瘤学家）的诊治、特殊的仪器设备、必要的监护和相关副作用的治疗，放疗和化疗的使用也大大增加了治疗肿瘤的费用，并且需要花费患者和医务人员长时间的治疗过程。早中期癌症治疗失败的明显标志是肿瘤的局部复发。在肿瘤部位的局部化疗潜在大量的好处，并能提高疗效和减少病人的发病率。载药的植入物直接应用于肿瘤部位，相对于传统的全身给药方式有以下优点：1）稳定的嵌入式药物分子与抗肿瘤活性，2）控制并延长了药物释放，以确保药物能扩散到各个分裂周期的肿瘤细胞中去，3）水溶性药物承载和释放，4）直接输送到病灶部位，从而减少药物的浪费，5）一次性给药，6）由于避免了化疗药物的全身循环，减少了副作用。在这项研究中我们的目标是调查的聚合物纳米纤维的潜在用途。因此，本论文的工作主要包括以下三部分：一、紫杉醇的担载和控制释放。紫杉醇属于油溶性抗肿瘤药物，可以直接溶解在具有生物降解能力的有机相溶液中，得到均一、透明的聚合物/药物混合液。采用传统的制备电纺丝方法就能完成在载体纤维内药物的完全包裹和可控释放。制备了紫杉醇/PEG-PLA电纺丝纳米纤维毡。电镜下显示紫杉醇完全包裹融入在纳米纤维中。因为选取PEG750-PLA作载体材料，在溶解释放阶段初期有部分的紫杉醇快速释放出来；而在Tris-HCl缓冲液中加入蛋白酶K，紫杉醇就可以持久、可控的缓慢释放出来。实验表明：紫杉醇/PEG-PLA纳米纤维毡对小鼠H22肝瘤细胞有显著的抑制和诱导凋亡作用，并表现出剂量、时间的依赖性。担载紫杉醇的PEG-PLA纤维毡局部化疗有效，可以延长小鼠的生存期，明显抑制肿瘤的生长，使肿瘤的体积增长缓慢甚至缩小。二．顺铂的担载和控制释放顺铂是一种水溶性抗肿瘤药物，为了在脂溶性聚合物中完全担载和可控释放水溶性的药物，采用了一种新的“乳液电纺丝”技术。此技术是巧妙的结合电纺丝技术和乳化技术，其原理是将水溶性药物溶于水中，以水溶液微液滴的形式在脂溶性聚合物中均匀分散，得到均一、稳定的W/O乳液，之后采用电纺丝技术，在聚合物的纤维中完全包裹水溶性药物。利用此项技术制备了Cis/PEG-PLA载药纤维毡。Cis以分子状态在PEG-PLA电纺丝纤维内部均匀分散，形成贮库型载药体系。实验表明：Cis/PEG-PLA纤维毡对大鼠H22肝瘤细胞有显著的抑制和杀伤作用，相对于紫杉醇抗肿瘤作用明显，对肝癌术后局部化疗有效，可以延长小鼠的生存期，明显抑制肿瘤的生长，使肿瘤的体积增长缓慢甚至不长。但在释放的初期阶段有顺铂“爆发”的释放，在一定程度上造成了全身毒性。三．改良式顺铂的多层聚乳酸纤维毡的应用制备顺铂的多层聚乳酸纤维毡应用在肝癌手术切除后小鼠局部，实验表明：改良式顺铂的多层聚乳酸纤维毡减少了顺铂的最初的“爆发”的释放，在一定程度上减少全身毒性，并延长药物释放提高杀伤肿瘤细胞的作用。这些结果为多层载药纳米纤维毡在局部化疗预防肝癌术后复发，单独或联合目前其他的治疗方案，提供了一个广阔的前景。更多还原

【Abstract】 Although the most effective treatment for patients with localizedliver cancer is surgical resection, long-term survival is dismal if thedisease recurs. The risk of local recurrence in early-stage liver cancer iscorrelated with the distance between the surgical margin and the primarytumor. Residual microscopic tumor cells at the surgical margin have beenidentified postoperatively in39%of patients following “curative” wedgeresection, suggesting that local recurrence arises from nearby occulttumor cells that remain after surgery.thus concurrent treatment withradiation and/or chemotherapy is often utilized with more aggressivecancer types, in an attempt to prevent recurrent tumor growth.For this reason,neoadjuvant chemotherapy and/or external beamradiation therapy are sometimes used to shrink particularlylarge tumors and/or ‘control’ regional disease prior to surgical excision,effectively ‘down-staging’ the disease before surgery in some patients.Radiation treatment, although generally associated with lower5-yearsurvival than surgery, can be curative for early stage cancers and is utilized as an alternative to resection in late stage patients includingprostate, breast, and lung cancers or those unable to tolerate surgery.Unfortunately, the acute and long-term toxicities and limited efficacyassociated with these adjuvant therapies have prevented their routine useas prophylactic interventions in all patients.Given that intravenous systemic chemotherapy is not specificallytargeted to the tumor, it is very difficult to achieve therapeutic levels ofdrug within or adjacent to the tumor. Furthermore, significantconcentrations of drug frequently accumulate in healthy tissue, leading tosevere side effects and dose-limiting toxicity. For example, almost halfthe dose of an intravenous injection of paclitaxel is eliminated during thefirst24hours, with less than0.5%of the total dose locally available totreat tumor within the lung. The use of radiation and chemotherapy alsosignificantly adds to the cost of cancer care due to the high material costsand the need for appropriate specialists including radiation and medicaloncologists and a robust support staff for delivery of therapy, appropriatemonitoring,and treatment of side effects. These treatments are timeconsuming for both patients and personnel, requiring frequent visits overmonths of therapy.Treatment failure in early and intermediate stage cancers, includinghigh locoregional recurrence rates, is indicative of the shortcomings seenwith the current standard of care for some malignancies. The potential benefits of localized chemotherapy at the tumor site are numerous and areintended to both enhance the efficacy of treatment and reduce patientmorbidity. Drug-loaded implants are administered directly at the site ofdisease, offering the following advantages over traditional systemicdelivery:1) stabilization of embedded drug molecules and preservation ofanticancer activity,2) controlled and prolonged drug release to ensureadequate diffusion and uptake into cancer cells over many cycles oftumor cell division,3) loading and release of water-insolublechemotherapeutics,4) direct delivery to the site of disease, resulting inless waste of drug,5) one-time administration of the drug, and6)diminished side effects due to the avoidance of systemic circulation ofchemotherapeutic drugs.In this study our objectives were to investigate the potential use ofpolymer nanofibers. Therefore, this thesis consists of the following threeparts:The first part was the successful incorporation and sustained releaseof Paclitaxel using “traditional solution-electrospinning”.As far as Paclitaxel is hydrophobic drug, it can be dissolved in thehydrophobic polymer/organic solvent system forming a transparent andhomogenous mixed solution. When the solution was electrospun bytraditional electrospinning setup, the drug could be perfectly incorporatedinto the hydrophobic polymer fibers. This case is termed as “traditional solution-electrospinning”.Paclitaxel/PEG750-PLA electrospun fiber mats were successfullyprepared by electrospinning. Paclitaxel/PEG-PLA fibers showed a rapidenough paclitaxel release at the very beginning and then provided asustained release of paclitaxel. For the delivery of antineoplastic drugs,certain amount of initial burst is actually required to achieve enoughinitial dosage. Of course, for the cancer cells that survive the initial stage,sustained drug release is necessary. So paclitaxel/PEG-PLA fiber mats aresuitable for liver cancer therapy. They can inhibit the propagation of therat H22liver cancer cells and induce the cell apoptosis. After treated withpaclitaxel/PEG-PLA fiber mats, the life span of the rats bearing cancerwas extended, and the volumes of tumors were distinctly shrunk.The second part was concentrated on incorporating cisplatin intohydrophobic polymer fibers by “emulsion electrospinning”.“Emulsionelectrospinn-ing”, i.e., to prepare an aqueous solution of a drug, toemulsify this aqueous solution in a polymer solution and to electrospinthe emulsion. Because the water may be evaporated quickly during thefiber stretching and solidification, the hydrophilic drug is expected to beencapsulated in the fibers.Cis-loaded PEG-PLA nanofibers with different Cis loadings wereprepared by “emulsion-electrospinning”. Cis was molecularly distributedinto the drug-loaded fibers, forming a reservoir-type drug-loaded system. Experimental results show: Cis/PEG-PLA fiber mat has significant effectof inhibition and killing on tumor cells in rats with H22induced liver, hasobvious anti-tumor effects compared with paclitaxel.It is the effectivelocal chemotherapy after liver resection for hepatocellular carcinoma, andcan prolong the survival of mice,inhibit tumor growth, the tumor volumegrowth is slow and even no growth. But in the early stages of release,"outbreak" released of cisplatin has caused systemic toxicity.The third part was the application of multilayer modifiedCisplatin-loaded polylactide electrospun nanofibers.MultilayeredCisplatin-loaded polylactide electrospun nanofibers is used in after theoperation of local liver cancer resection in mice.Experiments show that:multilayer modified Cisplatin-loaded polylactide electrospun nanofibersreduced cisplatin first "outbreak" release, reduced systemic toxicity, andprolonged the drug release to increasing tumor cell killing effect. Theseresults provide an encouraging prospect of using multilayered,drug-loaded electrospun nanofiber mats in local chemotherapy to preventtumor recurrence following HCC surgery, alone or combined withpresently employed treatment protocol.更多还原