project four:

quantitative assays of bone marrow genotoxicity

       
In instances of accidental radiation exposure or radiological terror events, incomplete or missing physical dosimetry will be the norm. Dental dosimetry is valuable, but does not address particulate or neutron exposures. Biodosimetry is therefore needed to make rational clinical management decisions, and for long-term carcinogenic risk assessments.

 
• Low-LET mouse experiments: As planned, these studies will be completed by the end of year 2. We plan to repeat the C3H dose response experiment, and also evaluate a limited number of doses with Atm null allele mice, and SCID mice. A challenge in this regard will be to find a supplier that can generate the necessary number of these mice within the specified age range.
• Low-LET rat experiments: These studies have begun (summer of 2007). Since the rat spleen is able to clear MN-containing erythrocytes, as is the case for the human spleen, these dose response and time-course experiments will be valuable for assessing the impact that this organ has on peripheral blood-based measurements.
• High-LET rodent experiments: These are underway. As noted above, we have expanded these studies to include flow cytometric measurements at both McMaster and Litron Laboratories.
• Radioprotecants: An in vivo mouse proof-of-principle experiment with amifostine is planned for May 2007. Assuming this is successful, we will collaborate with Project 1 investigators to study lead compounds for their ability to modulate MN-RET and RET responses to low-LET radiation.
• Inhalation radiation: These experiments will be performed this summer in collaboration with Project 2 investigators and will study the ability of MN-RET and RET endpoints to discriminate exposures that are persistent due to internalized radionuclides.
• Human 3-D marrow: The mouse 3-D culture has completed and the human culture optimization is underway. This is planned to be completed this year. As for the human amifostine protocol, we are re-submitting a protocol to IRB and hope for approval.
 
 
Project Four Personnel
 
Project 4 is developing assays emphasizing genotoxicity in the bone marrow; notably, the first human blood sample from a (consented) study subject was recently analyzed successfully. These data on hematopoietic genotoxicity will complement the physical dosimetry developed in Project 3. We believe that the genotoxicity data will also prove useful in the evaluation of the efficacy of the agents being proposed in Project 1. Marrow reactors have been developed, producing erythroblasts that respond to radiation injury (through micronuclei formation) in a dose dependent manner. In experiments performed in multiple laboratories, flow cytometry-based MN-RET and RET analyses provided reliable assessment of radiation bone marrow injury; the analytic techniques have proved to be transferable between laboratories with reproducible results. This method provides discrimination between individuals that have or have not been exposed to radiation with greatest sensitivity at doses of <1 Gy.
  

Project 4 : Communications & Publications

• Chen Y., Hyrien O., Nowak I., Tsai Y., Wang N., Wilkins R., Ferrarotto C., Dertinger S. Validation of high throughput micronucleus analysis in peripheral reticulocytes for radiation biodosimetry. 13th International Congress of Radiation Research July 7-12, San Francisco, 2007.
• Dertinger SD, Hyrien O, Chen Y. Flow cytometric scoring of radiation-induced micronuclei: reticulocyte- and lymphocyte-based approaches. Environmental Mutagen Society, Atlanta, Oct. 2007 (invited lecture).
• Dertinger SD, MacGregor JT, Hyrien O, Chen Y. Micronucleated CD71-positive reticulocytes: A cross-species bridging endpoint. 8th International Symposium on Chromosomal Aberrations, Awaji Island, Hyogo, Japan, Oct. 2007 (invited lecture).
• Dertinger SD, Miller RK, Brewer K, Smudzin T, Torous DK, Roberts DJ, Avlasevich SL, Bryce SM, Sugunan S, Chen Y. Automated human blood micronucleated reticulocyte measurements for rapid assessment of chromosomal damage. Mutat Res. 2007;626(1-2):111-9.
• Dertinger SD, Sugunan S, Ying T, Nowak I, Palis J, Chen Y. Micronucleated reticulocyte measurements: low dose radiation biodosimeter. Environmental Mutagen Society, 2006.
• Hyrien O., Dertinger S.D, Chen Y. Profile likelihood for dose estimation in radiation dosimetry studies. BiodosEPR 2006 Conference, 10-13 July 2006, Uniformed Services, University of the Health Sciences, Bethesda, Maryland.
• Hyrien O., Dertinger S.D., Chen Y. A quantitative analysis of the kinetics of reticulocytes and micronucleated reticulocytes in cancer patients receiving cancer therapy. The 10th World Multi-Conference on Systemics, Cybernetics and Informatics, WMSCI 2006, July 16-19, 2006, Orlando, Florida.
• Nowak I., Hyrien O., Chen Y. Micronucleus (MN) versus nucleoplasmic bridge (NPB) assessment for radiation biodosimetry in human lymphocytes. 13th International Congress of Radiation Research, July 7-12, San Francisco, 2007.
• Tsai Y, Ferrarotto C, Wang N, Wilkins R, Chen Y. Optimizing cytogenetic analysis for radiation-induced chromosomal aberration in C57Bl/6 Mice. 13th International Congress of Radiation Research, July 7-12, San Francisco, 2007
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