Abstract： Objective To investigate the therapeutic effects of the chemotherapeutic drug ACNU combined with hyperbaric oxygen (HBO) in the treatment of transplantation tumor of glioma stem/progenitor cells SU3.Methods The SU3 cells were inoculated subcutaneously into general NC nude mice which were kept in an independent ventilated cages (IVC).Following the development of the tumor,the tumor-bearing mice were sacrificed,and tumor tissues were harvested,then,inoculated subcutaneously into transgenic green fluorescence protein (GFP) nude mice.On the third day,the animals were randomly divided into 4 groups:the HBO group (n =7),the ACNU + HBO group (n =7),the ACNU group (n =7) and the control group (n =12).The first 2 groups were placed in the HBO-IVC without specific pathogens and treated with HBO,1 session a day for a duration of 100 minutes.The animals in the second and third groups were administered with ACNU abdominally at a dosage of 30 mg/kg,once a week for a duration of 3 weeks.The tumor volume was measured with the vernier caliper and the body mass of tumor-bearing mice was weighed with the balance weight,once every 3 days.At the end of the experiment,some tissues were collected to perform RT-PCR detection,the remaining tissues were used for pathological sections.Results As compared with those of the control group,changes in the transplantation tumor mass of various groups were as follows:The tumor mass for the ACNU + HBO group was (2 252.86 ± 1 062.54) mg (P =0.006);the tumor mass for the ACNU group was (1 914.28 ±744.55) mg (P=0.002);that for the HBO group was (4 680.00 ±2 538.40) mg(P =0.925);and that for the control group was (4 760.83 ± 1 989.18) mg.Histopathological examination indicated that necrotic hemorrhage foci in tumor tissues could be frequently observed in the control group,and numerous neoformative vessels around the hemorrhagic site could also be found.Proliferation of vascular endothelial cells was quite active under microscopy.However,those pathological changes in the HBO group could scarcely be seen.In the ACNU and the ACNU plus HBO groups,there was no fresh hemorrhage,and neither was there remote hemorrhage.Vascular proliferation was relatively inactive.At the same time,the mRNA expression levels of TNF-α and CD105 were obviously lower than those of the control group (P =0.028,P =0.008).Conclusions ACNU coupled with HBO seemed to have marked tumor inhibitive effect on human glioma in the subcutaneous nude mice model.Though single HBO therapy produced little prohibitive effect on tumor growth,it failed to promote tumor growth either.For this reason,in the rehabilitation of patients with malignant tumor,HBO therapy should not be regarded as a taboo.