Apoptosis and meiotic segregation in ejaculated sperm from Robertsonian translocation carrier patients

BACKGROUND: To better understand the infertility of patients with Robertsonian translocation, the biochemical and ultrastructural apoptotic characteristics of apoptosis in the sperm of patients and fertile donors were studied. METHODS: Ejaculated sperm samples of seven Robertsonian translocation carriers and seven fertile donors were analyzed after cryopreservation. The proportion of both viable and dead spermatozoa expressing activated caspases was detected by flow cytometry through the use of different specific carboxyfluorescein-labeled caspase inhibitors. Sperm DNA fragmentation was evaluated by the TUNEL method. The percentages of intact spermatozoa or spermatozoa with ultrastructural features of apoptosis, immaturity or necrosis were estimated by electron microscopy. Meiotic segregation analysis was performed by FISH. RESULTS: Significantly lower concentration, forward motility and normal morphology of spermatozoa were found in ejaculated samples of the Robertsonian patients than fertile donors. Compared with the control group, in Robertsonian translocation carriers: (i) the caspase assays showed a significantly increased (P < 0.05) proportion of viable spermatozoa with activated poly-caspases (57.4 versus 25.8%), caspase-3 (43.5 versus 13.4%), caspase-8 (44.4 versus 17.1%) and caspase-9 (42.4 versus 10.0%); (ii) the rate of DNA fragmentation was higher (26.3 versus 12.8%); and (iii) sperm ultrastructural examination highlighted a higher percentage of immature (28.0 versus 10.0%) and apoptotic (24.5 versus 18.5%) spermatozoa. FISH study showed predominant normal/balanced spermatozoa (78.34-85.53%). CONCLUSIONS: These results show a predominant proportion of balanced and normal gametes and higher numbers of spermatozoa showing apoptosis and immaturity features in oligoasthenozoospermic Robertsonian translocation carriers than in fertile donors. This suggests defects in spermatogenesis and especially spermiogenesis of these infertile patients.