Early single administration of 4F to irradiated monkeys reduced RI apoptosis at the BM CD34⁺ cell level.

The mitochondrial transmembrane potential (MTP) was evaluated ex vivo in BM CD34⁺ cells 6 hours (H6) after TBI (4 hours after 4F injection) using DiOC₆ uptake expressed as mean fluorescence intensity (MFI). Results are expressed as mean indices (± SEM) using an internal standard. Each index is the ratio of DiOC₆ uptake MFI in CD34⁺ cells to DiOC₆ uptake MFI in granulocytes from a given BM sample. Unlike 4F-treated animals (n = 3), untreated animals (n = 3) exhibited a pattern of MTP hyperpolarization at the BM CD34⁺ cell level, which is an early marker of apoptosis. H0 indicates before irradiation.