Quality and functional aspects of sperm retrieved through assisted ejaculation in men with spinal cord injury

Objective

To assess semen quality, sperm DNA fragmentation, and mitochondrial activity in fertile men as well as in men with spinal cord injury who were collecting semen through different methods.

Design

Prospective controlled study.

Setting

Academic research environment.

Patient(s)

Men with spinal cord injury who achieved ejaculation through electroejaculation (n = 12) and penile vibratory stimulation (n = 10); 30 fertile control men without spinal cord injury.

Intervention(s)

Electroejaculation or penile vibratory stimulation, semen analysis according to World Health Organization guidelines, morphology by Kruger's strict criteria.

Main Outcome Measure(s)

Semen was analyzed according to World Health Organization guidelines; morphology was analyzed according to Kruger's strict criteria. Sperm DNA fragmentation, as assessed by the TUNEL technique, was classified as percentage positive. Mitochondrial activity was assessed by incorporation of diaminobenzidine by mitochondria. Cells were classified as I (all active) to IV (all inactive).

Result(s)

The control group presented a statistically significantly higher percentage of sperm with active mitochondria and a statistically significantly lower percentage of sperm with inactive mitochondria. Although sperm DNA fragmentation was not significantly different when considering collection method (electroejaculation: 30; 8.4; penile vibratory stimulation: 31.2; 8), both groups presented statistically significantly higher DNA fragmentation than did controls (11.8; 4.5). A strong inverse correlation was observed between sperm DNA fragmentation (assessed by in situ DNA nick end labeling) and mitochondrial activity in the case of electroejaculation (r = −0.714), but not in the case of penile vibratory stimulation (r = 0.060).

Conclusion(s)

Spinal cord injury led to a decrease in sperm mitochondrial activity and an increase in sperm DNA fragmentation, and the latter is a sign of testicular alterations. Studies should focus on improving the testicular environment in these men.

Key Words: DNA damage, mitochondria/metabolism, spinal cord injury, assisted ejaculation