Human umbilical-cord-blood mononucleated cells enhance the survival of lethally irradiated mice: dosage and the window of time

The purpose of this study was to evaluate the window of time and dose of human umbilical-cord-blood (HUCB) mononucleated cells necessary for successful treatment of radiation injury in mice. Female A/J mice (27–30 weeks old) were exposed to an absorbed dose of 9–10 Gy of 137Cs γ-rays delivered acutely to the whole body. They were treated either with 1 × 108 or 2 × 108 HUCB mononucleated cells at 24–52 h after the irradiation. The antibiotic Levaquin was applied 4 h postirradiation. The increased dose of cord-blood cells resulted in enhanced survival. The enhancement of survival in animals that received 2 × 108 HUCB mononucleated cells relative to irradiated but untreated animals was highly significant (P < 0.01). Compared with earlier studies, the increased dose of HUCB mononucleated cells, coupled with early use of an antibiotic, extended the window of time for effective treatment of severe radiation injury from 4 to 24–52 h after exposure.