Macrophage-derived exosomes carrying RAD50 attenuate oxidative DNA damage and p53–p21-dependent S-phase arrest in spermatogenic cells

AIMS: Occupational heat and blast overpressure impair spermatogenesis, and whether repair capacity supplied from outside the germ cell can lift the resulting block has not been tested. METHODS: GC-2 spermatocytes received 1000 shock-wave pulses then 100°C for 40 s, and C57BL/6 mice received a 10% methane blast with intratesticular temperature unrecorded. Both were treated with exosomes from J774A.1 macrophages profiled by nanoparticle tracking and proteomics. RESULTS: . p53 and p21 increased while cyclin-dependent kinase 2 (CDK2) and Cyclin A2 decreased, arresting a larger fraction of cells in S phase than in controls. RAD50 was detected among 3603 exosomal proteins and ranked in the top tier of the displayed abundance panel, and exosome treatment increased its co-precipitation with MRE11. Treatment also lowered superoxide, normalized the four-cycle regulators and returned the S-phase fraction toward control, with testis moving in the same direction. CONCLUSION: These data indicate that macrophage-derived exosomes relieve the redox-triggered p53-p21 checkpoint by supplying repair capacity.