Camptothecin can increase the quantity of apoptotic bodies in a conditioned medium from human umbilical cord-derived mesenchymal stem cell culture

Introduction: Recent studies have demonstrated that extracellular vesicles, particularly apoptotic bodies (ABs) from mesenchymal stem cells (MSCs), play an important role in MSC-mediated immune regulation. However, studies on the apoptosis and ABs of umbilical cord mesenchymal stem cells are still limited. This study aimed to investigate the effects of camptothecin on increasing ABs in a conditioned medium consisting of a human umbilical cord-derived mesenchymal stem cell (hUCMSC) culture. Methods: hUCMSCs were cultured in an expansion medium supplemented with 5 µM camptothecin (apoptosis inducer). The ABs were isolated using the centrifugation approach. The shape of the ABs was confirmed by reverse microscopy and the size of the collected population was confirmed using a particle size analyzer. The protein concentration of ABs was quantified using the Bradford assay. Apoptotic cells and ABs were stained with an optimized procedure using a FITC Annexin V/Dead Cell Apoptosis Kit, and the fluorescent signal was analyzed using ImageJ software and flow cytometry. Results: The protein concentrations of the ABs obtained in a conditioned medium without and with camptothecin after 48 h were 3.933 ± 0.037 µg and 5.567 ± 0.072 µg, respectively. The fluorescence signal analysis also showed that the number of apoptotic bodies also increased from 24 h (14.87 ± 1.84%) to 96 h (36.3 ± 3.99%). Conclusion: The results show that camptothecin can trigger hUCMSC apoptosis and increase the number of ABs in the conditioned medium. This research is a foundation for further studies into apoptosis and ABs in hUCMSCs.