灌注的空间测量，实体肿瘤间质流体压力和脂质体积累
Summary
The heterogeneous intra-tumoral accumulation of liposomes has been linked to an abnormal tumor microenvironment. Herein methods are presented to measure tumor microcirculation by perfusion imaging and elevated interstitial fluid pressure (IFP) using an image-guided robotic system. Measurements are compared to the intra-tumoral accumulation of liposomes, determined using volumetric micro-CT imaging.
Abstract
脂质体的异质肿瘤内积累是其功效的关键决定因素。既混沌肿瘤微循环和高架IFP被链接到基于纳米技术的药物递送系统的异质肿瘤内分布，如脂质体。在本研究中，肿瘤微循环，升高的IFP，和纳米颗粒的积累之间的关系，通过体内实验进行了研究。这是通过使用动态对比增强计算机断层扫描（DCE-CT）和使用连接到微CT扫描仪的新型图像引导的机器人针放置系统肿瘤IFP的测量肿瘤微循环的评估来实现的。脂质体的肿瘤内积聚是由纳米颗粒脂质体制剂稳定地包封造影剂碘海醇（CT-脂质体）的基于图像的CT评价来确定。 CT成像允许的空间分布的共定位肿瘤血流动力学，IFP和CT-脂质体蓄积在乳腺癌的个体皮下异种移植物小鼠模型。测量导致发现该灌注和血浆体积分数是脂质体的肿瘤内分布的强介体。此外，结果表明，IFP起着通过调节血流介导的脂质体分布的间接作用。
Introduction
测量纳米颗粒的药物递送系统的肿瘤内积累可以提供，以确定是否细胞毒性药物的适当浓度已在肿瘤内实现的一个重要工具。 “图象能够”脂质体系统的发展允许非侵入性和定量的体内检测用成像方式如正电子发射断层扫描（PET）1，光学荧光2，和计算机断层扫描（CT）3的药物递送载体的， 4和磁共振成像（MRI）5。成像已被用于确定药代动力学和脂质体递送系统的生物分布和以显示跨学科和肿瘤内的异质性在纳米颗粒累积6,7的程度。然而，纳米粒子成像本身并不能识别已经给他们可怜的积累和分配贡献了生物屏障。这方面的知识是最重要的，将r更有效的配方憩的发展和战略，以提高肿瘤内积聚8。它已被证实的治疗策略可以应用于调节从而提高纳米颗粒运输9特定生物屏障。此外，纳米颗粒制剂已经开发了专门克服特定生物传输阻挡10。在这两种情况下，生物屏障的测量可以被用来指导使用合适的纳米颗粒的药物递送策略的。
肿瘤微循环和升高IFP被认为是纳米颗粒的肿瘤内蓄积的两个关键因素，如脂质体，在实体瘤9,11。然而，有助于脂质体积累穷人服务的其他障碍包括致密的细胞外基质，防渗血管和实体组织的压力12。这些障碍在一个时空相关方式，与异常血流和升高的组织间隙液压作为驱动纳米颗粒的初始传送和外渗的两个重要因素。如先前所讨论的，建立肿瘤微循环，升高的IFP和脂质体的肿瘤内蓄积之间的关系是当务之急脂质体的成像数据的适当解释。在此定量的方法来衡量实体瘤，肿瘤微循环，IFP升高和积累纳米之间的关系呈现。这是通过使用容积CT成像，肿瘤微循环使用动态对比增强计算机断层成像执行的CT脂质体的造影剂的肿瘤内分布的共定位测量完成，使用图像引导的机器人针定位系统，肿瘤IFP称为对CT-IFP机器人13。
Protocol
Representative Results
Discussion
本文中所呈现用于基于图像的测量方法能够肿瘤微循环特性，IFP，和CT-脂质积累的空间分布的确定。以前的尝试涉及这些属性都依赖于执行在多个肿瘤携带动物散装测量，因此缺乏灵敏度阐明负责该已普遍被观察到纳米尺寸的药物输送系统15在肿瘤内积聚的异质性的机制。 DCE-CT提供了测量在肿瘤微循环特性的肿瘤内变化的工具，立体CT提供的CT-脂质沉积动力学的准确描绘，与CT-IFP机器人系…
Disclosures
The authors have nothing to disclose.
Acknowledgements
The authors would like to thank Dr. Javed Mahmood for assistance with culturing MDA-MB-231 cells and implanting the MDA-MB-231 xenografts, Linyu Fan for preparing the CT-liposomes. Shawn Stapleton is grateful for funding from the Natural Sciences and Engineering Research Postgraduate Scholarships Program and the Terry Fox Foundation Strategic Initiative for Excellence in Radiation Research for the 21st Century (EIRR21) at CIHR. This study was supported by grants from the Terry Fox New Frontiers Program (020005) and the Canadian Institutes of Health Research (102569).
Materials
| MDA-MB-231 metastatic breast adenocarcinoma tumor cells | ATCC | HTB-26 | |
| Dulbecco's Modified Eagle Medium (DMEM) | Life Technologies | 11965-092 | |
| Fetal Bovine Serum (FBS) | Sigma-Aldrich | F1051 | |
| HyClone Penicillin-Streptomycin 100x Solution | GE Healthcare Life Sciences | SV30010 | |
| Trypsin-EDTA (0.05%), phenol red | ThermoFisher Scientific | 25300-054 | |
| 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) | Avanti Lipids Inc., USA | 850355P | |
| Cholesterol (CH) | Avanti Lipids Inc., USA | 700000P | |
| 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-poly(ethylene glycol) 2000 (DSPE-PEG2000) | Avanti Lipids Inc., USA | 880128P | |
| Omnipaque (Iohexol) 300 mg of iodine/mL | GE Healthcare, CA | ||
| 80 nm pore size Track-Etch polycarbonate membranes | Whatman Inc., USA | ||
| 200 nm pore size Track-Etch polycarbonate membranes | Whatman Inc., USA | ||
| 10 mL Lipex Extruder | Nothern Lipids Inc, CA | ||
| Dialysis Bag Molecular Weight Cut Off (MWCO) of 8 kDa | Spectrum Labs, USA | ||
| 750,000 Nomical Molecular Weight Cut Off (NMWC) Tangential flow column | MidGee ultrafiltration cartridge, GE Healthcare, CA | ||
| Peristaltic pump | Watson Marlow Inc., USA | ||
| UV spectrometer | Helios γ, Spectronic Unicam, USA | ||
| 90Plus particle size analyzer | Brookhaven, Holtsville, USA | ||
| eXplore Locus Ultra micro-CT system | GE Healthcare, CA | Manipulated using CT-Console Software | |
| AxRecon GPU-based Reconstruction | Acceleware Corp. CA | ||
| 27G Catheter SURFLO Winged Infusion Set | Terumo Medical Products, USA | SV*27EL | |
| PE20 polyethylyne tubing | Becton Dickinson, USA | 427406 | |
| Pen tip 25G × 3.5′′ Whitacre spinal needle | Becton Dickinson, USA | 405140 | IFP needle |
| P23XL pressure transducer | Harvard Apparatus, CA | P23XL | |
| PowerLab 4/35, Bridge Amp, with LabChart Pro 7.0 | ADInstruments Pty Ltd., USA | PL3504, FE221 | IFP acquisition system and acquisition software |
| CT-Sabre Small Animall Intervention system (CT-IFP Robot) | Parallax Innovations, CA | Manipulated using CT-IFP robot Control Software | |
| CT-IFP robot alignment software | Custom Matlab software | ||
| DCE-CT Analysis Software | Custom Matlab software | ||
| Matlab 2013b | Mathworks, USA |
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