Higher sperm DNA damage in semen from men with spinal cord injuries compared with controls

Semen from men with spinal cord injuries (SCI) and control subjects was investigated for sperm DNA damage using the sperm chromatin structure assay. Three experiments were performed. In experiment 1, the DNA fragmentation index (DFI) was compared in semen from SCI subjects and control subjects. In experiment 2, the % DFI was determined in repeated ejaculations to examine the effect of anejaculation on DFI. In experiment 3, the DFI was determined in neat vs processed semen to examine the effect of necrospermia or leukocytospermia on DFI. The results of experiment 1 showed a significantly higher mean (+/- SEM) DFI in the semen of SCI subjects (65.2% +/- 6.6%; range, 42.3%-90.8%) compared with control subjects (15.4% +/- 2.9%; range, 5.4%-33.5%; P <.001). In experiment 2, there was a high correlation between the DFIs obtained in the first semen specimens and the DFIs obtained 3 days later in semen of the same SCI subjects (r(s) =.94; P <.02). In experiment 3, the results showed no significant difference between mean DFI in aliquots of neat semen (79.3% +/- 9.9%) vs matched aliquots of semen processed to remove dead sperm and leukocytes in SCI subjects (75.2% +/- 16.1%). The DFI is higher in semen from men with SCI vs controls. The cause of this condition is unknown but does not seem to be due to prolonged anejaculation or to the proximate conditions of necrospermia or leukocytospermia. The relevance of these findings to fertility outcomes with SCI male partners remains to be determined.