Studies On Hematopoietic Function After High Dose Irradiation

Objective: To analyze the hematopoietic function after high dose irradiation. To seek molecular biology methods which can evaluate the severity of hematopoietic injury. To screen new biomarkers for the diagnosis and treatment of acute radiation sickness. Methods: To explore mortality rate, peripheral blood cell counts, CFU-GM counts, cell cycle retardation and apoptosis from mice strain C57BL/6J after y rays total body irradiation of different doses. To study the expression level of some hematopoietic growth factor and receptors of mouse bone marrow after high dose irradiation. To search differentially expressed genes from mouse bone marrow after high dose irradiation using DNA microarray. Results: 6.5Gy, 7.5Gy, 8.5Gy and lOGy were determined which represent the seventy of hematopoietic injury. The following criterions were found to be dose correlated: Nadir of white blood cell and reduction phase of platelet after high dose irradiation; Percentage of G2/M retardation cells in bone marrow and S retardation cells in spleen 6h post irradiation; Percentage of apoptosis cells 12h post irradiation in bone marrow and 6h post irradiation in spleen and thymus. RT-PCR was used to clone partial sequences of SCF, G-CSFR, EPOR, c-mpl and c-kit from mouse bone marrow. Combining RT-PCR and Southern hybridization, the post irradiation expression level of these hematopoietic growth factor and receptors was observed in mouse bone marrow. No significant changes were found within 24h after high dose irradiation. Since the severe depletion of hematopoietic cells, no sufficient amount of total RNA can be obtained for investigation 48h after high dose irradiation. New gene NM-025383 was found to be radiation associated through DNA microarray screening and was cloned from mouse bone marrow. Conclusion: The 7 dose correlated criterions may help evaluate the severity of hematopoietic injury. The successful cloning of 5 low copy genes make it possible to investigate their expression level in vivo after high dose irradiation. Combining RT-PCR and Southern hybridization is a practical method to analyze expression level of low copy genes in vivo. Functional research of radiation associated NM-025383 is feasible.