Characterization of a partial-body irradiation model with oral cavity shielding in nonhuman primates.

Characterization of a novel partial-body irradiation (PBI) shielding strategy in nonhuman primates (NHP; rhesus macaques), aimed at protecting the oral cavity, with respect to various gastrointestinal acute radiation syndrome (GI-ARS) syndrome parameters as well as buccal ulceration development. NHPs were irradiated using a Cobalt-60 gamma source, in a single uniform dose, ranging from 9-13 Gy and delivered at 0.60-0.80 Gy min. Animals were either partially shielded via oral cavity shielding (PBI) or underwent total-body irradiation (TBI). Clinical manifestations of GI-ARS, and also radiation-induced hematology and clinical chemistry changes, following PBI were comparable to the PBI NHP GI-ARS model utilizing shielding of the distal pelvic limbs and were significantly milder than TBI at similar radiation doses. Nadir citrulline levels were comparable between PBI and TBI but signs of recovery appeared earlier in PBI-treated animals. The PBI model prevented oral mucositis, whereas the TBI model presented buccal ulcerations at all tested radiation dose levels. Taken together, these results suggest that the PBI model is a suitable alternative to traditional PBI. For GI-ARS investigations requiring orally administered medical countermeasures, PBI confers added value due to the prevention of oral mucositis over traditional PBI.