Foster K A, Yazdanian M, Audus K L
Department of Pharmaceutical Chemistry, University of Kansas, Lawrence 66047, USA.
J Pharm Pharmacol. 2001 Jan;53(1):57-66. doi: 10.1211/0022357011775190.
The objective of this study was to examine the uptake mechanisms of fluorescent polystyrene microspheres of various diameters and surface chemistry by two human cell lines derived from the respiratory epithelium, A549 and Calu-3. Briefly, A549 and Calu-3 cells were grown to confluence in 12-well cluster plates and the uptake of fluorescent microspheres by the cells was determined at various time points. The amount of microspheres internalized by the cells was determined by correcting for non-specific binding to the cell surface. The data showed that A549 cells appeared to have more phagocytic activity than Calu-3 cells. Albumin-coated microspheres as large as 3 microm diameter can be internalized by A549 cells. The amount of internalization by A549 cells observed for 0.5-microm diameter albumin-coated microspheres was approximately 10-times greater than that observed for 1-microm diameter spheres and approximately 100-times greater than values observed for 2- and 3-microm diameter beads. Transmission electron micrographs confirmed that the microspheres were internalized by the cells. Uptake experiments conducted with Calu-3 cells indicated that albumin-coated microspheres were neither bound nor internalized by the cells. The effect of microsphere surface chemistry on the uptake mechanism indicated that amidine microspheres were internalized more rapidly and to a greater extent by both A549 and Calu-3 cells than carboxylate microspheres and non-coated microspheres. This phenomenon is thought to be attributed to masking of the negative polystyrene core by the positive amidine functional group; this effect was less marked for the carboxylate microspheres. These results suggest that A549 and Calu-3 cells can internalize microspheres and that size and effective charge played an important role in the uptake process.
本研究的目的是检测两种源自呼吸道上皮的人类细胞系A549和Calu-3对不同直径和表面化学性质的荧光聚苯乙烯微球的摄取机制。简而言之，将A549和Calu-3细胞在12孔培养板中培养至汇合，并在不同时间点测定细胞对荧光微球的摄取情况。通过校正细胞表面的非特异性结合来确定细胞内化的微球量。数据显示，A549细胞似乎比Calu-3细胞具有更强的吞噬活性。直径达3微米的白蛋白包被微球可被A549细胞内化。观察到A549细胞对直径0.5微米的白蛋白包被微球的内化量约为直径1微米微球的10倍，约为直径2微米和3微米微球的100倍。透射电子显微镜照片证实微球被细胞内化。用Calu-3细胞进行的摄取实验表明，白蛋白包被微球既不与细胞结合也不被细胞内化。微球表面化学性质对摄取机制的影响表明，脒基微球比羧酸盐微球和未包被微球更快且更大量地被A549和Calu-3细胞内化。这种现象被认为是由于正性脒基官能团掩盖了负性聚苯乙烯核心；这种效应在羧酸盐微球中不太明显。这些结果表明，A549和Calu-3细胞能够内化微球，并且大小和有效电荷在摄取过程中起重要作用。
