Ionizing irradiation can cause bone marrow failure and death. Very few effective therapeutic agents are currently available for this condition. It was previously published that human recombinant growth hormone promotes hematopoietic and immune reconstitution after stem cell transplantation. In this study, we investigated the effects of growth hormone on radiation-induced injury. In a sublethally irradiated model (BALB/c mice, 5 Gy), the recovery of platelets in peripheral blood was significantly accelerated after treatment with human recombinant growth hormone at a dose of 20 μg, i.p., once a day, for 35 days starting within one hour after irradiation. Similar trends were also observed in total white blood cells and all lymphocyte subsets tested (T, B, NK cells). These data suggest that growth hormone can promote hematopoietic and immune recovery after irradiation. We then tested whether growth hormone can rescue animals from lethal irradiation. BALB/c mice were irradiated with 7.5 Gy and treated with growth hormone using the same regimen as that used in the sublethal model. As demonstrated in the figure, 5 out of 10 mice in the growth hormone treated group survived more than 80 days after irradiation, whereas 9 out of 10 mice died by day 25 in the saline control group. Growth hormone was still effective when tested using higher dose of radiation (8.5 Gy). These findings demonstrate that human recombinant growth hormone has significant radioprotective effects even when given after total body irradiation.

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Topics:
somatotropin, somatropin, recombinant growth hormone, hematopoietic stem cell transplantation, pancytopenia, saline solutions, whole-body irradiation, mice, mice, inbred balb c, blood platelets

Disclosure: No relevant conflicts of interest to declare.

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2006, The American Society of Hematology
2006
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