The invention relates to method for cultivating stem cells in vitro, comprising the following steps: providing a sample comprising stem cells and cultivating the stem cells by subjecting the sample to a treatment for a first period of time. The treatment is carried out under hypothermic conditions having a defined temperature and a defined atmosphere, wherein the temperature does not exceed 15° C. and the atmosphere has an oxygen content not exceeding 21% (v/v). Thereby, the first period of time is 4 days to 4 weeks.