IntroductionRegenerative therapy is a developing field in medicine. In the production of cell products for these therapies, hygienic management is even more critical than in the production of a chemical drug. At the same time, however, care is required with the use of decontamination agents, considering their effects on cell viability and characteristics. To date, hydrogen peroxide (H2O2) is most widely used for decontamination in pharmaceutical plants and cell processing facilities.MethodsIn this study, we examined the effects of residual H2O2 in the atmosphere of cell processing units after decontamination on the viability and proliferation of mesenchymal stem cells derived from human bone marrow.ResultsWe detected residual H2O2 sufficient to affect cell proliferation and survival even more than 30 h after decontamination ended. Our results suggest a longer time period is required before starting operations after decontamination and that the operating time should be as short as possible.ConclusionsHere we show the effects of post-decontamination residual H2O2 on the viability and proliferation of mesenchymal stem cells derived from human bone marrow, which may provide us with important information about the hygienic management of cell processing facilities.