Determination and modeling of kinetics of cancer cell killing by doxorubicin and doxorubicin encapsulated in targeted liposomes
Determination and modeling of kinetics of cancer cell killing by doxorubicin and doxorubicin encapsulated in targeted liposomes
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DOI：
10.1158/0008-5472.can-03-0654
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发表时间：
2004-01-15
期刊：
影响因子：
11.2
通讯作者：
Szoka, FC
中科院分区：
文献类型：
--
作者：
Eliaz, RE;Nir, S;Szoka, FC
已经设计了各种数学方法来将细胞培养物中药物的细胞毒性效应与添加到细胞培养基中的药物浓度相关联。当药物在溶液中游离时，这样的方法可以令人满意地解释药物反应，但是当药物在药物递送系统如脂质体中递送时，该方法变得有问题。为了解决这个问题，我们已经开发了一个简单的模型，假设药物的细胞毒性效力是细胞内药物水平的函数在一个关键的隔室。在暴露于药物后，细胞死亡在滞后时间后开始，并且细胞杀伤率取决于关键细胞内隔室中的药物量。在暴露于药物后的任何时间，计算的培养物中的细胞数量考虑了细胞增殖速率、细胞杀伤速率、平均细胞内药物浓度和细胞杀伤的滞后时间。我们应用该模型比较阿霉素（DOX）或包封在脂质体中的DOX对培养的B16 F10黑色素瘤细胞的细胞毒性作用，脂质体靶向CD 44。CD 44是与透明质酸结合的表面受体，并在各种癌细胞（包括B16 F10）上过表达。我们以前已经表明，包封在透明质酸靶向脂质体中的药物比游离药物更有效。该模型需要在细胞与各种浓度的游离或包封药物孵育3小时后测定细胞相关的DOX，并在暴露于药物后的不同时间定量细胞数量。包封药物的摄取大于游离药物的摄取，并且包封药物与游离药物的细胞结合比率在0.5 μ g/ml时为1.3，在20 μ g/ml DOX时增加至3.3。结果表明，胶囊化药物的增强的效力可能源于其增强的摄取。然而，在某些情况下，当加入较大量的游离药物，使得细胞内药物的量超过从包封的药物获得的量时，包封的药物的活细胞的数量仍然显著较小。这一发现表明，对于给定量的细胞内DOX，包封形式比游离药物更有效地杀死B16 F10细胞。结果在动力学模型中表示为包封药物相对于游离药物的细胞杀伤效力的速率常数大5-6倍。该模型提供了一个定量的框架，比较细胞毒性作用时，在培养的细胞中应用的药物在游离形式或在一个交付系统。
Various mathematical approaches have been devised to relate the cytotoxic effect of drugs in cell culture to the drug concentration added to the cell culture medium. Such approaches can satisfactorily account for drug response when the drugs are free in solution, but the approach becomes problematic when the drug is delivered in a drug delivery system, such as a liposome. To address this problem, we have developed a simple model that assumes that the cytotoxic potency of a drug is a function of the intracellular drug level in a critical compartment. Upon exposure to drug, cell death commences after a lag time, and the cell kill rate is dependent on the amount of drug in the critical intracellular compartment. The computed number of cells in culture, at any time after exposure to the drug, takes into account the cell proliferation rate, the cell kill rate, the average intracellular drug concentration, and a lag time for cell killing. We have applied this model to compare the cytotoxic effect of doxorubicin (DOX), or DOX encapsulated in a liposome that is targeted to CD44 on B16F10 melanoma cells in culture. CD44 is the surface receptor that binds to hyaluronan and is overexpressed on various cancer cells, including B16F10. We have shown previously that the drug encapsulated in hyaluronan-targeted liposomes was more potent than was the free drug. The model required the determination of the cell-associated DOX after the cells were incubated with various concentrations of the free or the encapsulated drug for 3 h, and the quantification of cell number at various times after exposure to the drug. The uptake of encapsulated drug was greater than that of the free drug, and the ratio of cell association of encapsulated: free drug was 1.3 at 0.5 mug/ml and increased to 3.3 at 20 mug/ml DOX. The results demonstrate that the enhanced potency of the encapsulated drug could stem from its enhanced uptake. However, in certain cases, where larger amounts of the free drug were added, such that the intracellular amounts of drug exceeded those obtained from the encapsulated drug, the numbers of viable cells were still significantly smaller for the encapsulated drug. This finding demonstrates that for given amounts of intracellular DOX, the encapsulated form was more efficient in killing B16F10 cells than the free drug. The outcome was expressed in the kinetic model as a 5-6-fold larger rate constant of cell killing potency for the encapsulated drug versus the free drug. The model provides a quantitative framework for comparing the cytotoxic effect in cultured cells when applying the drug in the free form or in a delivery system.