Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna, Austria.
Eur J Pharm Biopharm. 2012 Oct;82(2):367-75. doi: 10.1016/j.ejpb.2012.07.016. Epub 2012 Aug 5.
A unique structural and functional configuration renders the human urothelium, one of the hardest to overcome biological barriers, and accounts for critical shortcomings in the adjuvant localized therapy of bladder cancer and other severe medical conditions. Strategies to improve intravesical drug absorption are urgently sought, but so far have hardly adopted biorecognitive delivery vectors that are more specifically tailored to the natural characteristics of the target site. The efficient cytoinvasion of uropathogenic bacteria, mediated via a mannose-directed FimH lectin adhesin, and malignancy-dependent differences in bladder cell glycosylation point to considerable unrealized potential of lectins as targeting vectors on the molecular/functional and recognitive level. Here, we outline the ability of wheat germ agglutinin (WGA) to induce endocytosis of conjugated payload in human urothelial SV-HUC-1 cells after stable adhesion to internalizing receptors. A panel of model bioconjugates was prepared by covalently coupling one to six WGA units to fluorescein-labeled bovine serum albumin (fBSA). Cytoadhesive capacity was found to directly correlate to the degree of modification up to a critical threshold of on average three targeting ligands per conjugate. The highly specific, glycan-triggered interaction proved essential for endosomal sorting and was followed by rapid (<60min) and extensive (>40%) internalization. fBSA/WGA bioconjugates were processed analogously to the free lectin, irrespective of the significantly higher molecular weight (100-300kD). Durable entrapment of conjugates in acidic, perinuclear compartments without kiss-and-run recycling to the plasma membrane was found in both single cells and monolayers. Our results assign promising potential to glycotargeted delivery concepts in the intravesical setting and offer new perspectives for the application of complex biologicals in the urinary tract.
一种独特的结构和功能配置使人体尿路上皮成为最难克服的生物屏障之一，这也是膀胱癌和其他严重医疗状况的辅助局部治疗的关键缺陷所在。人们迫切需要寻找提高膀胱内药物吸收的策略，但迄今为止，几乎没有采用更能针对靶部位自然特性进行定制的生物识别递药载体。尿路致病性细菌通过甘露糖定向的 FimH 凝集素粘附素介导的高效细胞侵袭，以及膀胱癌细胞糖基化的恶性依赖性差异，表明凝集素作为靶向载体在分子/功能和识别水平上具有相当大的未实现潜力。在这里，我们概述了小麦胚芽凝集素 (WGA) 在与内化受体稳定粘附后诱导人尿路上皮 SV-HUC-1 细胞内吞共轭有效载荷的能力。通过将一个至六个 WGA 单元共价偶联到荧光标记的牛血清白蛋白 (fBSA) 上，制备了一系列模型生物缀合物。细胞粘附能力与修饰程度直接相关，直到每个缀合物平均有三个靶向配体的临界阈值。高度特异性的糖触发相互作用对于内体分选至关重要，并随后迅速 (<60min) 和广泛 (>40%) 内化。fBSA/WGA 生物缀合物的处理与游离凝集素类似，无论分子量显著增加 (100-300kD)。在单细胞和单层中都发现了缀合物在酸性、核周区室中的持久滞留，而没有到质膜的 Kiss-and-Run 再循环。我们的结果赋予了糖靶向递药概念在膀胱内环境中的应用前景，并为复杂生物制剂在泌尿道中的应用提供了新的视角。
