The authors have shown recently that for the two types of adult stem cells (hematopoietic stem cells and intestinal epithelium stem cells), the "ischemia/reperfusion" reaction can be developed in vivo. The damaging action of this reaction onto stem cells can be diminished by an injection of a source of NO-radicals into the animal's body during reperfusion, since NO-radicals are capable of decreasing the negative effect of radicals produced after oxygen access into the ischemic tissues. The authors believe that these data may be used in the development of new approaches for the protection of cell systems of organism renewal after the damaging action of various agents.