Acrosome activity is lower in sperm from men with spinal cord injury compared to age-matched, healthy control subjects

Abstract

Objective: Men with spinal cord injury have poor semen quality. While their sperm concentrations tend to be similar to that of normal men, their sperm motility and sperm viability are below average. Conflicting data exist regarding the fertilization potential of sperm from men with spinal cord injury. Among the several tests available to determine spermatozoa’s sperm function and fertilization potential, the acrosome reaction test is relatively simple, inexpensive, reproducible, and has been correlated with subfertility, infertility, and in-vitro fertilization success rates. The goal of this study was to compare acrosin activity in sperm from men with spinal cord injury versus age-matched healthy control subjects. A commercially available acrosome reaction test, the Acroscreen™ assay, was used for this purpose. This assay measures the total acrosin activity in spermatozoa. Design: A between-subjects design was used to compare acrosin activity in subjects with spinal cord injury versus age-matched healthy control subjects. Materials and Methods: Semen samples from 5 subjects with spinal cord injury (mean age in years: 33 ± 2.7 standard error of the mean) and 7 control subjects (37 ± 3.4 years) were measured for acrosin activity using the Acroscreen™ photometric enzyme method. In an IRB-approved protocol, semen was collected from men with spinal cord injury by the standard methods of penile vibratory stimulation (n = 4), or electroejaculation (n = 1). Control subjects produced semen specimens by masturbation. Specimens were first processed on standard PureSperm 40/80™ gradients to remove seminal plasma, which contains protease inhibitors, and other cellular debris. The acrosin activity for the processed specimens was then calculated using optical densities obtained by the photometric enzyme method described in the Acroscreen™ kit. Mean acrosin activity for subjects with spinal cord injury was compared to that of control subjects using analysis of variance. Results: The mean acrosin activity in μIU acrosin/million sperm, was 106.3 ± 29.6 for subjects with spinal cord injury and 215.5 ± 35.2 for control subjects (p < 0.05). Conclusion: The sperm of men with spinal cord injury exhibit significantly less acrosin activity compared to normal controls, indicating a potential lowered fertilization capacity of sperm from these patients. Supported by: the State of Florida Specific Appropriations and the Miami Project to Cure Paralysis.