BACKGROUND:: SHG44, a kind of malignant glioma cell line, is easy to cultivate with stable biomedical properties and widely used in the animal models of tumors. The current studies focus on inhibiting SHG44 growth by drugs, gene transfection and ionizing radiation. There have been no reports describing the effects of mesenchymal stem cells on biological characteristics of SHG44. OBJECTIVE:: To investigate the cell cycle and the number of SHG44 cells which were directly and indirectly co-cultured with human umbilical cord mesenchymal stem cells. METHODS:: Human umbilical cord mesenchymal stem cells and SHG44 cells were directly co-cultured in the 24-well plate and indirectly co-cultured in the Transwell plate. A control group was designed for the direct and indirect co-culture separately. After co-culture for 3 d, cells were observed under fluorescence microscope, and SHG44 cells were collected for detection of SHG44 cell cycle by flow cytometry. RESULTS AND CONCLUSION:: Compared with corresponding controls, the number of SHG44 cells fluorescently labeled decreased after directly co-cultured with MSCs (P < 0.05); the number of SHG44 cells fluorescently labeled had no change after indirectly co-cultured with MSCs (P > 0.05). The proportion of SHG44 cells at G0/G1 stage was significantly higher than that in the control group (P < 0.05). The results confirmed that human umbilical cord mesenchymal stem cells cultured in vitro can inhibit the proliferation of SHG44 cells by direct and indirect ways in vitro.Liang AM, Liang S, Fan RT, Tian Y, Chi LK, Shi XY, Liu JY, Guan FX, Yang B. Human umbilical cord mesenchymal stromal cells inhibit the growth of SHG44 cells under direct and indirect co-cultivation.Zhongguo Zuzhi Gongcheng Yanjiu. 2012;16(32): 5891-5896. [http://www.crter.org/crter-2012-qikanquanwen.html](Figure is included in full-text article.)