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

Purpose: 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.Materials and methods: 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^-1. Animals were either partially shielded via oral cavity shielding (PBI_OS) or underwent total-body irradiation (TBI).Results: Clinical manifestations of GI-ARS, and also radiation-induced hematology and clinical chemistry changes, following PBI_OS 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_OS and TBI but signs of recovery appeared earlier in PBI_OS-treated animals. The PBI_OS model prevented oral mucositis, whereas the TBI model presented buccal ulcerations at all tested radiation dose levels.Conclusions: Taken together, these results suggest that the PBI_OS model is a suitable alternative to traditional PBI. For GI-ARS investigations requiring orally administered medical countermeasures, PBI_OS confers added value due to the prevention of oral mucositis over traditional PBI.