Characterization of death of human fetal bone marrow CD34+ cells after different dose of γ-irradiation

Objective To investigate the characterization of death of the human hematopoietic stem cells after irradiation. Methods Human fetal bone marrow mononuclear cells were irradiated with different doses of 60Co γ-rays at different high dose rates.Apoptosis and necrosis of CD34+ cells were analyzed by flow cytometry,following three-color labeling with PE-CD34/FITC-Annexin V/7AAD at different times after irradiation. Results The death of CD34+ cells after 5 Gy and 8 Gy irradiation showed a continuous process of reproductive death during the first week,and the main death type was apoptosis.A majority of CD34+ cells died of necrosis during the first day after 10 Gy and 12 Gy irradiation,and all of them died within a week. Conclusion Niches are continuously vacated every day within a week following irradiation and reproductive death of hematopoietic stem cells occurred.