Echogenic polymersomes for triggered contents release

项目摘要 聚合物囊泡是由两亲性嵌段共聚物制备的双层囊泡。虽然他们有 与其它纳米颗粒相比具有许多优点（例如更长的循环时间、更高的稳定性、 携带亲水和疏水药物），它们作为细胞毒性药物和成像的载体的应用 代理人仍然不发达。在上一个合同（1R01 GM114080）中，我们开发了聚合物囊泡 谷胱甘肽触发的内容物释放。我们通过一种独特的制备方法使聚合物囊泡产生回声 在系统中封装气泡的协议，使我们能够通过诊断超声成像 扫描仪通过结合适当的配体，我们将聚合物囊泡靶向癌细胞和细胞内 细胞器如细胞核或线粒体在培养的球状体中达到至少200 μ m的穿透力。 它们在线性和非线性超声信号中也表现出50 dB和25 dB的增强， 稳定上一个奖项产生了25篇同行评审的出版物，两个书籍章节，一项专利，5项专利。 博士毕业生℃下 在更新申请中，我们将制备靶向的、穿透深层组织的回声聚合物囊泡 响应于不同程度的缺氧（2 - 10%氧气），用于药物递送和同时的超声成像。 缺氧在许多病理条件下发展，包括实体瘤、肺动脉高压、缺血， 高原反应、脑损伤、中风等。实体瘤中的缺氧引发细胞外基质的重塑， 上皮细胞向间充质细胞的转化、细胞存活、转移、癌症干细胞的形成，以及 对化疗和放疗有显著抵抗力。缺氧进一步促进胶原蛋白丰富， 纤维性细胞外基质（结缔组织增生），增加间质压力并限制扩散， 毒品的运输。在本申请中，我们将使用三阴性乳腺癌作为缺氧的替代物， 实体瘤我们将对缺氧触发的内容物释放、回声反射、 超声波衰减和散射，以及抗癌药物沿着 一种在实体瘤缺氧区域的干性抑制剂。 我们会按照三个具体目标进行建议的研究。(1)合成缺氧反应 聚合物，制备组织穿透聚合物囊泡并对触发内容物进行机理研究 release. (2)制备回声低氧响应聚合物囊泡，表征回声，研究其 机制，并优化成像以阐明超声诱导的内容物释放。(3)证明 缺氧反应性回声聚合物囊泡的功能功效使用细胞和小鼠模型， 低氧壁龛我们的方法是创新的，原因如下。它提出（i）聚合物囊泡的递送 深入到实体瘤，包括缺氧的壁龛，克服结缔组织屏障，这仍然是外 由于扩散限制的边界，（ii）缺氧响应药物释放，这将是有用的，在许多其他 疾病，（iii）转录抑制剂的递送，其可以到达并杀死肿瘤深处的癌症干细胞， 以及最后（iv）允许超声成像和超声-超声波成像的回声聚合物囊泡的双重功能性。 诱导释放。从我们的研究中获得的知识也有可能针对其他疾病状况 其中发生缺氧介导的恶化，包括多发性实体瘤、肺动脉高压、缺血， 高海拔高山病、脑、肾和肺损伤，特别是移植后。

PROJECT SUMMARY Polymersomes are bilayer vesicles prepared from amphiphilic block copolymers. Although they have many advantages compared to other nanoparticles (such as longer circulation time, higher stability, ability to carry both hydrophilic and hydrophobic drugs), their applications as carriers for cytotoxic drugs and imaging agents remain under-developed. During the previous award (1R01 GM114080), we developed polymersomes for glutathione-triggered contents release. We rendered the polymersomes echogenic by a unique preparation protocol that encapsulated air bubbles in the system, allowing us to image them by a diagnostic ultrasound scanner. By conjugating appropriate ligands, we targeted the polymersomes to cancer cells and intracellular organelles such as the nucleus or mitochondria attaining their penetration at least 200 m in cultured spheroids. They also exhibited 50 dB and 25 dB enhancement in linear and nonlinear ultrasound signals and adequate stability. The previous award resulted in 25 peer-reviewed publications, two book chapters, one patent, and 5 students graduating with Ph.D. degree. In the renewal application, we will prepare targeted, deep-tissue-penetrating echogenic polymersomes responsive to varying degrees of hypoxia (2–10% oxygen) for drug delivery and concurrent ultrasound imaging. Hypoxia develops in many pathological conditions, including solid tumors, pulmonary hypertension, ischemia, altitude sickness, brain injury, stroke, etc. Hypoxia in solid tumors triggers remodeling of the extracellular matrix, epithelial-to-mesenchymal transition, cell survival, metastasis, the formation of the cancer stem cells, and significant resistance to chemo- and radiotherapy. Hypoxia further promotes the development of collagen-rich, fibrous extracellular stroma (desmoplasia), which increases the interstitial pressure and limits the diffusion and transport of the drugs. In this application, we will use triple-negative breast cancer as a surrogate for hypoxic solid tumors. We will conduct mechanistic studies on hypoxia-triggered contents release, echogenicity, ultrasound attenuation and scattering, and the cellular consequences of delivering an anticancer drug along with a stemness inhibitor in the hypoxic regions of solid tumors. We will conduct the proposed studies with three Specific Aims. (1) Synthesize hypoxia-responsive polymers, prepare tissue-penetrating polymersomes and perform mechanistic studies on triggered contents release. (2) Prepare echogenic hypoxia-responsive polymersomes, characterize echogenicity, investigate its mechanism, and optimize imaging to elucidate ultrasound induced content release. (3) Demonstrate the functional efficacy of the hypoxia-responsive echogenic polymersomes using cellular and mouse models of hypoxic niches. Our approach is innovative for the following reasons. It proposes (i) delivery of polymersomes deep into the solid tumors, including hypoxic niches, overcoming the desmoplastic barrier, which remained out of bounds due to diffusional limitations, (ii) hypoxia responsive drug release, which would be useful in many other diseases, (iii) delivery of transcription inhibitor, that can reach and kill cancer stem cells deep inside the tumors, and finally (iv) dual functionality of echogenic polymersomes allowing ultrasound imaging and ultrasound- induced release. The knowledge gained from our studies has the potential also to target other disease conditions where hypoxia-mediated worsening occur, including multiple solid tumors, pulmonary hypertension, ischemia, high-altitude mountain sickness, brain, kidney, and lung injury, especially following transplantation.