Besides the haemopoietic stem cell, mesenchymal stem cell (MSC) is an adult stem cell in the marrow. It has the ability to self-renew, differentiate into various kinds of tissue and regulate the immunological system. MSC possess low immunogenicity. It shows the immunosuppressive ability in vitro and has function of inducing immune-tolerance. MSC suppress accrementition of T cell respone to the allotigen and mitogen and hinderes the development of cytotoxic T lymphocyte cell. In addition, MSC can influence antigen presenting cell, natural kill cell, B cell, and so on.

Objective To study the role of capsaicin on improving the sensitivity of cholangiocarcinoma (CCA) cells to 5 fluorouracil(5-FU)and to investigate its molecular mechanism.Methods The MTT and animal experiment were performed to study the effect of capsaicin on the sensitivity of CCA cells to 5-FU,and the q-PCR and Western blot were performed to study its molecular mechanism.Results The effect of 5-FU inhibiting the growth of CCA cells and in vivo was significantly enhanced by capsaicin (60 μmol/L),as well as the apoptosis induced by 5-FU (P ＜ 0.01).In molecular mechanism study,capsaicin down-regulated the expression of beclinl and atg5,but inhibited the 5-FU-induced autophagy of CCA cells.In addition,capsaicin effectively increased the phosphorylation levels of S6 (S235/236) and AKT (S473).Conclusions Capsaicin can promote cell apopto sis and inhibit cell autophagy to improve the sensitivity of CCA cells to 5-FU significantly,which maybe associated with the activation of PI3K/AKT/mTOR pathway in CCA cells.