In this article, we provide an update review on the implication of the assessment of human sperm function and the management of male infertility in clinical assisted reproductive technology (ART) known as in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). In most ART clinics, the assessment of male fertility is still mainly based on routine semen analysis but it is inaccurate in predicting sperm fertilizing ability. Thus it is often difficult to determine if IVF or ICSI will be an optimal treatment for patients in the initial cycle. Before introduction of ICSI, frequency of low ( <30%) fertilization rate in IVF was very high (20-35% of patients). Evidence suggests that sperm defects are the major contributors to complete failure of fertilization in IVF. Most common sperm defects are oligozoospermia, asthenozoospermia and teratozoospermia though many of the patients are shown to be normal in routine semen analysis. In the literature, many new sperm function tests have been developed, including sperm DNA normalities assessed by Acridine Orange (AO), sperm-zona pellucida (ZP) binding, the ZP-induced acrosome reaction (AR) , sperm-ZP penetration and recently hyaluronan binding assay (HBA). For routine semen analysis, sperm morphology is one of the most useful values for the prediction of sperm function but is also the most difficult test to perform accurately and consistently. Oocytes that failed to fertilize in clinical IVF/ICSI are valuable biological materials for testing sperm function. The human ZP selectively binds sperm with normal morphology and an intact acrosome. The ZP-induced AR is highly correlated with sperm-ZP penetration and disordered ZP-induced AR causes infertility in about 25% men with unexplained infertility with normal semen analysis. Both oligozoospermic (sperm count < 20 x 10(6) /ml) and severe teratozoospermia (strict normal sperm morphology < or =5%) men have a very high ( >70%) frequency of defective sperm-ZP interaction. Thus patients with defects of sperm-ZP interaction should be identified and treated with ICSI since they have high risk of low or zero fertilization rate in IVF. HBA test highly correlates with sperm motility and normal morphology but provides no additional information about sperm fertility. Clinical value of sperm DNA normalities detected by AO for the prediction of ART outcomes is currently still inconclusive and requires further investigation. In conclusion, addition of some of these new sperm tests to routine semen analysis could significantly improve the management of male infertility in clinical ART.
DNA Damage ; Humans ; Infertility, Male ; diagnosis ; physiopathology ; therapy ; Male ; Sperm Count ; Sperm Injections, Intracytoplasmic ; Sperm Motility ; Sperm-Ovum Interactions ; Spermatozoa ; physiology

AIMTo produce biologically active recombinant human (rh) ZP proteins in a human cell for use in sperm function tests.

METHODSThe human embryonic kidney cell line 293T was employed to produce rhZP1, rhZP2 and rhZP3 proteins individually and together by co-expression. Presence of these proteins in the culture medium and cell lysate was assessed by Western blotting analysis. The effect of the recombinant proteins on the human AR was assessed.

RESULTSRhZP2 and rhZP3 were secreted into the culture medium, whereas rhZP1 was found only in the cell lysate. Interestingly, when all zona pellucida proteins were co-expressed in the same cells, rhZP1 was also secreted into the culture medium. However, despite the presence of all three ZP proteins in sufficient concentration and evidence of heavy glycosylation on gel electrophoresis, biological activity to induce the AR was not observed.

CONCLUSIONRhZP1, rhZP2 and rhZP3 were successfully expressed in the human embryonic kidney cell line 293T. It appears that an interaction amongst these proteins may be required for release of rhZP1 from the cell. Although this approach is not satisfactory for producing active human ZP proteins, it makes a significant contribution to the understanding of the structural and functional characteristics of the ZP proteins.

Acrosome Reaction ; drug effects ; Blotting, Western ; Cell Line ; Egg Proteins ; analysis ; genetics ; pharmacology ; Embryo, Mammalian ; Female ; Fluorescent Antibody Technique ; Gene Expression ; Glycoside Hydrolases ; metabolism ; Glycosylation ; Humans ; Kidney ; Male ; Membrane Glycoproteins ; analysis ; genetics ; pharmacology ; Receptors, Cell Surface ; analysis ; genetics ; Recombinant Proteins ; analysis ; pharmacology ; Zona Pellucida Glycoproteins