Conditioned Media of Human Umbilical Cord Blood Mesenchymal Stem Cell-derived Secretome Induced Apoptosis and Inhibited Growth of HeLa Cells

BACKGROUND: Secreted factors contained in conditioned media (CM) of human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) known as secretome, was suspected to have important roles in regulating cells. This study was conducted to investigate the role of CM-hUCB-MSCs-derived secretome in apoptosis and growth of HeLa cells. METHODS: HeLa cells were treated with secretome in various concentrations (0, 0.2, 2 and 20%) for 4 and 48 hours. Trypan blue exclusion assay was performed to detect cell viablity. Meanwhile sub-G1 apoptotic assay was performed to detect apoptotic cells. The transition of mitochondrial transmembrane potential (TMP), which occurs in the apoptotic process, was analyzed by mitochondrial membrane potential (Delta Psi M) assay. Both sub-G1 and Delta Psi M assays were performed using FACSCanto low cytometer. Statistical analyses were conducted using IBM SPSS Statistics to detect signiicance level at p< 0.05. RESULTS: Secretome signiicantly induced cell death starting at concentration of 0. 2% within a 24-hour period (p< 0.05). Secretome signiicantly induced cell death in concentration and time dependent manner (p< 0.05). The cell death was then conirmed as apoptosis through sub-G1 analysis. Due to the underlying apoptotic mechanism, we found distinct decrease of TMP, indicating an increase in mitochondrial membrane permeability of HeLa cells. In addition, we found that HeLa cell growth was inhibited partially by secretome. CONCLUSION: Taken together, we conclude that CMhUCB-MSCs- derived secretome significantly induced apoptosis of HeLa cells in a concentration and time dependent manner through mitochondrial apoptotic pathway. The secretome might also play important role in inhibiting HeLa cell growth.