Human Umbilical Cord Mesenchymal Stem Cells Kill Breast Cancer Cells By Triggering Apoptosis

Stem cells,known as self-renewing and differentiation potential,can be divided into embryonic stem cells and adult stem cells according to their developmental stages.Embryonic stem cells are also named totipotential stem cells,meaning that they can differentiate into all tissue cells.However,the clinical application of embryonic stem cells has tumorigenic risks and ethical disputes.Mesenchymal stem cells,a class of adult stem cells,have caused focuses owing to their ability of proliferation,differentiation,angiogenesis promotion and immune regulation.They were considered as perfect seed cells in the field of cell-replacing and tissue-engineering.Moreover,mesenchymal stem cells can migrate directly into tumor sites to pro-tumor or anti-tumor.About that,the differences of the sources of mesenchymal stem cells or the types of tumor cells can lead to different effects.The mechanisms of mesenchymal stem cells as seed cells involve two main aspects: on one hand,mesenchymal stem cells differentiated into functional cells to replace damaged cells.On the other hand,mesenchymal stem cells secreted a variety of cytokines activated the function of the body.In this paper,we confirmed the above mechanisms in vitro and in vivo.Further,we suggest that umbilical cord mesenchymal stem cells have killing effect on tumor cells by promoting tumor cells apoptosis.Specifically,the apoptotic rates of tumor cells are related to the proportion of umbilical cord mesenchymal stem cells and tumor cells.We suggested,the supernatant collected from umbilical cord mesenchymal stem cells has obvious killing effect on tumor by promoting tumor cells in a dose and time dependent manner,it can replace the function of umbilical cord mesenchymal stem cells on this aspect.We also suggested,the mechanisms of umbilical cord mesenchymal stem cells considered as seed cells is the combination of ‘cell to cell' and ‘bystander effect',but the latter one is dominant.We explored the effects of umbilical cord mesenchymal stem cells and their supernatant on the growth of tumor cells in vitro and in vivo by flow cytometry,laser scanning confocal microscopy,pathological section staining,immunohistochemical staining,transmission electron microscope and other technical methods.After analyzing the results of all experiment based on cell and molecular biology,we suggested that umbilical cord mesenchymal stem cells have anti-tumor potential and may be a new therapeutic method in the treatment of breast cancer.We thought that this paper may provide experimental and theoretical support for the tumorigenic risks of umbilical cord mesenchymal stem cells.