Characterization of human sperm populations using conventional parameters, surface ubiquitination, and apoptotic markers
Received 5 October 2005; received in revised form 21 July 2006; accepted 21 July 2006. published online 21 November 2006.
Objective
To directly compare distinct assays proposed to monitor human sperm quality and possibly preselect sperm populations for assisted reproductive technology (ART).
Design
Analysis of human sperm sample quality using several methodologies.
Setting
Academic and clinical institutions.
Patient(s)
Samples from consenting patients undergoing routine semen analysis or ART.
Interventions
Human sperm samples were analyzed in terms of World Health Organization parameters and processed for annexin V, terminal deoxynucleotidyl transferase–mediated dUTP nick-end labeling of DNA (TUNEL), and the sperm–ubiquitin tag immunoassay (SUTI). Samples were analyzed both by flow cytometry and fluorescence microscopy.
Main Outcome Measure(s)
Correlations among apoptotic markers (outer leaflet phosphatidylserine exposure, membrane integrity, and DNA fragmentation), external ubiquitination, and semen parameters in human spermatozoa.
Result(s)
Nonviable sperm, TUNEL-positive cells, and ubiquitin fluorescence intensity means inversely correlate with semen parameters. Apoptotic markers do not correlate with sperm surface ubiquitination. Normozoospermic samples have a higher number of viable cells and lower DNA fragmentation compared with samples with abnormal parameters. Nonviable sperm are more prevalent in samples with low counts and poor morphology but not low motility. Not all sperm with morphologic abnormalities present surface ubiquitination.
Conclusion(s)
Sperm quality is inversely correlated with lack of viability, DNA fragmentation, and ubiquitin fluorescence intensity means. However, none of the apoptotic markers correlate with ubiquitin labeling. Elimination of defective sperm cells prior to ART using surface markers (annexin V, ubiquitin) seems unwarranted at this stage.
aCenter for Neuroscience and Cell Biology, Department of Zoology, University of Coimbra, Coimbra, Portugal
bDepartment of Maternal-Fetal Medicine, Genetics and Human Reproduction, University Hospitals of Coimbra, Coimbra, Portugal
cHistocompatibility Centre of Coimbra, Coimbra, Portugal
Reprint requests: João Ramalho-Santos, Ph.D., Center for Neuroscience and Cell Biology, Department of Zoology, University of Coimbra, 3004-517 Coimbra, Portugal (FAX: +351 239 855789).
Supported by a grant from the Portuguese National Science Foundation (Fundação para a Ciência e Tecnologia, FCT) to J.R.-S. (POCTI/ESP/38049/2001). S.V. and A.P.S. are supported by Ph.D. grants from FCT, Portugal.
ABSTRACT