Objective To investigate the characteristics of the bone marrow mesenchymal stem cell(MSC)in children with aplastic anemia(AA)in vitro,and the expressions of tumor necrosis factor -α-induced protein -8 -like 2(TIPE2)in the bone marrow,and the correlation between the level of TIPE2 mRNA with γ-interferon(IFN -γ)and IL -6 in AA patients.Methods Bone marrow samples were collected from 1 8 children with AA(AA group)and 8 children with bone injury (control group)who were hospitalized in Jinan Children′s Hospital from January 201 2 to June 201 5.MSC were isolated and cultured.The morphology of MSC was observed and immune phenotype was detected.The TIPE2 mRNA was detected by using real -time fluorescence quantitative PCR,and the levels of IFN -γand IL -6 were detected by using enzyme linked immunosorbent assay.Results Different sizes had been presented in the primi-tive MSC of AA patients,but the third passage MSC until 80% confluence had manifested the uniform convergence with long spindle and swirl distribution.In the sixth passage,cells showed degenerative change.The primitive and first pa-ssage MSC in patients with AA was longer than that in the controls.CD73 ,CD1 05 ,CD44 and CD90 were expressed in MSC,while CD34 ,CD45 ,CD271 expressed rarely.The level of TIPE2 mRNA in AA patients (5.29 ±1 .56)was obviously lower than that of the control group(8.68 ±2.00),and the difference was significant(t =-4.48,P <0.01 ).The con-centration of IFN -γ[(5.48 ±1 .97)ng/L]and IL -6[(5.43 ±1 .92)ng/L]in AA patients were higher than those of the control group[(3.40 ±1 .24)ng/L,(3.79 ±0.92)ng/L],and the differences were significant (t =2.70, 2.26,all P <0.05).The level of TIPE2 mRNA in AA patients was negatively related with IFN -γand IL -6(r =-0.838,-0.658,all P <0.05),but there was no significant correlation between them in the control group (all P >0.05).Conclusions The proliferation of MSC is significantly reduced in patients with AA.TIPE2,as an important role to stabilize the immune system,plays an important role in the occurrence of AA by its low expression and up -regula-ting the expression of inflammatory factors.