Quantitative Determination of Doxorubicin in the Exosomes of A549/MCF-7 Cancer Cells and Human Plasma Using Ultra Performance Liquid Chromatography-tandem Mass Spectrometry

In cancer therapy, exosomes efflux enhances resistance of cancer cells toward anticancer agents through mediating the transport of anticancer drugs outside the cells. In this study, a rapid, simple and highly sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination of Doxorubicin (DOX) in exosomes of cancer cells and human plasma using Ketotifen as an internal standard (IS). Plasma samples spiked with DOX and two cancer cell lines (A549 & MCF-7) were incubated with different concentrations of DOX and IS. The analytes were then extracted with methanol after protein precipitation and the chromatographic separation was carried out using a C18 column, with a mixture of acetonitrile-water- formic acid (85:15:0.1%, v/v/v) as mobile phase. Multiple reaction monitoring (MRM) was utilized to monitor the protonated precursor to product ion transitions of / 544.25 > 397.16 and / 310.08 > 96.97 for the quantification of DOX and IS, respectively. The method was linear over ranges of 1-1000 ng/mL for DOX in plasma and 2-1000 ng/mL for DOX in exosome samples. The lower limit of quantification of this method was 1 ng/mL, 2 ng/mL and 2 ng/mL in human plasma, A549 & MCF-7 cells respectively. Intra- and inter day precision of all quality control concentrations were less than 10.33% and the accuracy values ranged from -4.82 to 12.60%. The optimized UPLC-MS/MS method proved to be fast, specific, simple and highly sensitive and was successfully applied for the estimation of DOX in the exosomes of cancer cells and plasma.