Teo Boon M, van der Westen Rebecca, Hosta-Rigau Leticia, Städler Brigitte
Aarhus University, Aarhus, Denmark.
Biochim Biophys Acta. 2013 Oct;1830(10):4838-47. doi: 10.1016/j.bbagen.2013.06.022. Epub 2013 Jun 27.
Liposomes have gained immerse attention in the field of drug delivery as carriers of therapeutic molecules. Their modification with a polymer either to make them stealth (e.g. using PEG) and/or more stable (e.g. using poly(dopamine) (PDA)) is a crucial aspect to improve their performance e.g. the blood circulation time. Despite their potential, there are only a few commercialized liposome-based formulations for intravenous drug delivery. Hence, there is still considerable need to address the challenges involved in the design and characterization of liposomal therapeutics. In the latter case, it is of paramount importance to consider the dynamic in vivo environment, e.g. the interstitial fluidic pressure in tumors, blood flow, or bile flow in the liver.
The PEGylation of PDA films was characterized by quartz crystal microbalance with dissipation monitoring, and the optimized protocol was used to assemble PEGylated PDA coated liposomes (LPDA_PEG). Dynamic light scattering, a plate reader, a flow cytometer and a cytotoxicity assay were used to characterize the liposomes and quantify cellular association/uptake and cell viability in the presence and absence of shear stress after 30min and 4h. The immortalized skeletal mouse myoblast (C2C12) cell line was chosen as model cancer cells, and a hepatic cell line (HepG2) was selected due to their importance in nanosized drug carrier clearance from the system in the liver.
The presence of hydrophilic cargo did not affect the PDA assembly process. In the absence of shear stress, there was no difference in cellular uptake/association of both PDA coated liposomes (LPDA) and LPDA_PEG for hepatocytes while myoblasts preferentially internalized/associated with LPDA. In the presence of shear stress, hepatocytes preferentially internalized/associated with LPDA after 30min, while there was only a significant difference for myoblasts after 4h. The cell viability remained unaffected in all cases.
LPDA_PEG are a promising platform towards drug delivery. The nature of cells and fluidic flow are important factors to be considered in their characterization using cell cultures.
These findings will contribute in the better understanding of polymer coated liposomes with cells. The importance of microfluidics in cell culture based characterization is demonstrated, and this will eventually affect the way advanced drug delivery vehicles are designed and characterized prior to animal experiments.
脂质体作为治疗分子的载体，在药物递送领域受到了广泛关注。用聚合物对其进行修饰，使其具有隐形功能（如使用聚乙二醇（PEG））和/或更稳定（如使用聚多巴胺（PDA）），是提高其性能（如血液循环时间）的关键方面。尽管脂质体具有潜在优势，但用于静脉给药的基于脂质体的商业化制剂却很少。因此，仍有相当大的需求来应对脂质体疗法设计和表征中涉及的挑战。在后一种情况下，考虑体内动态环境至关重要，例如肿瘤中的间质流体压力、血流或肝脏中的胆汁流动。
通过具有耗散监测的石英晶体微天平对PDA膜的聚乙二醇化进行表征，并使用优化方案组装聚乙二醇化PDA包被的脂质体（LPDA_PEG）。使用动态光散射、酶标仪、流式细胞仪和细胞毒性测定法对脂质体进行表征，并在存在和不存在剪切应力的情况下，于30分钟和4小时后量化细胞结合/摄取及细胞活力。选择永生化的小鼠骨骼肌成肌细胞（C2C12）细胞系作为模型癌细胞，并选择肝细胞系（HepG2），因为它们在纳米药物载体从肝脏系统中清除方面具有重要作用。
亲水性货物的存在不影响PDA组装过程。在没有剪切应力的情况下，对于肝细胞，PDA包被的脂质体（LPDA）和LPDA_PEG的细胞摄取/结合没有差异，而成肌细胞优先内化/结合LPDA。在存在剪切应力的情况下，30分钟后肝细胞优先内化/结合LPDA，而4小时后成肌细胞才有显著差异。在所有情况下细胞活力均未受影响。
LPDA_PEG是一种有前途的药物递送平台。细胞性质和流体流动是使用细胞培养对其进行表征时需要考虑的重要因素。
这些发现将有助于更好地理解聚合物包被的脂质体与细胞的相互作用。证明了微流控技术在基于细胞培养的表征中的重要性，这最终将影响在动物实验之前先进药物递送载体的设计和表征方式。
