Fractions of Percoll eliminated sperm: increased sperm yield in percoll wash

Ganglioside GT1b protects human spermatozoa from hydrogen peroxide-induced DNA and membrane damage

We have reported previously that various gangliosides, the sialic acid containing glycosphingolipids, provide protection against sperm injury caused by reactive oxygen species (ROS). In this study, we investigated the effect of treatment of human spermatozoa with ganglioside GT1b on hydrogen peroxide (H(2)O(2))-induced DNA fragmentation and plasma membrane damage. Single-cell gel electrophoresis (Comet assay) used in the assessment of sperm DNA integrity showed that in vitro supplemented GT1b (100 microm) significantly reduced DNA damage induced by H(2)O(2) (200 microm) (p < 0.05). Measurements of Annexin V binding in combination with the propidium iodide vital dye labelling demonstrated that the spermatozoa pre-treated with GT1b exhibited a significant increase (p < 0.05) in the percentage of live cells with intact membrane and decreased phosphatidylserine translocation after exposure to H(2)O(2). Flow cytometry using the intracellular ROS-sensitive fluorescence dichlorodihydrofluorescein diacetate dye employed to investigate the transport of the extracellularly supplied H(2)O(2) into the cell interior revealed that ganglioside GT1b completely inhibited the passage of H(2)O(2) through the sperm membrane. These results suggest that ganglioside GT1b may protect human spermatozoa from H(2)O(2)-induced damage by rendering sperm membrane more hydrophobic, thus inhibiting the diffusion of H(2)O(2) across the membrane.

Analysis of in vitro migration patterns of human spermatozoa by a petri dish-based horizontal column

Spermatozoa are required to travel a considerable distance in vivo to meet the oocyte at the fertilization site. However, none of the existing in vitro tests critically evaluates migration of sperm to assess their potential of reaching the oocyte. On the other hand, an in vivo model is not suitable for this type of study because of ethical and technical constraints. In the present study we utilized a horizontal column technique to analyze sperm migration. Migratory characteristics of fresh, unwashed semen sperm and sperm undergoing various treatments were examined in vitro using a Petri dish-based horizontal fluid column. The procedure involved loading a sperm sample into the column and determining sperm concentration, motility, and viability at different column segments for different migration durations (6, 12, 24, 48, and 72 h). All sperm samples produced an exponential migration pattern in all durations of migration. Propagation along the column edge, tendency to exit from the column, and hiding in the blind pouches were some of the important characteristic features exhibited by the migratory sperm. Variations in migration patterns were documented among semen donors, between fresh and frozen semen, and between washed and unwashed sperm. Prolonged postejaculation time diminished migratory potential. The recovery of sperm in the column end was independent of seminal variables with the exception of oligozoospermia. These observations suggest that the Petri dish-based horizontal column is effective for analyzing sperm migration characteristics for prolonged periods. The potential of this migration assay in predicting the in vivo potential of spermatozoa to reach the fertilization site will be worth exploring.

Differential effect of common laboratory treatments on hypoosmotic swelling responses of human spermatozoa

PURPOSE

The impact of some of the common laboratory interventions on the hypoosmotic swelling (HOS) responses of human-spermatozoa was investigated.

METHODS

The semen samples underwent different laboratory treatments prior to the standard HOS test, which involved incubation of sperm in the hypoosmotic solution. Fresh semen served as a control for all treatment groups and underwent the same HOS procedure. The HOS-reactive spermatozoa and the type of HOS reactions (swelling types) in each group were identified under a phase-contrast microscope for comparison.

RESULTS

All the seven types of HOS responses documented in fresh semen sperm also occurred in the laboratory-processed sperm. The total HOS responses of sperm that underwent cryopreservation, heat shock, and Percoll wash were significantly different from those of the corresponding control. Percoll washing of semen influenced HOS subtypes a and g; cryopreservation affected subtypes a, b, c, and d; and heat shock altered subtypes a, f, and g. In contrast, prolonged postejaculation and cold shock did not affect any of the HOS responses. None of the treatments influenced the d and e responses.

CONCLUSIONS

These results indicate that the total HOS response value and specific response subtypes are significantly affected by some of the laboratory treatments but not others.

Assessment of the quality of frozen serum by spectrophotometric analysis and sperm bioassay

Serum is an integral part of media used for in vitro fertilization (IVF) and andrology work. Previous studies showed that the IVF results could benefit if sera were screened for deleterious effects before use. Such screening is impractical when fresh sera are used but may be feasible if the serum is frozen prior to use. This study assessed the impact of freezing on the quality of serum. A total of 158 serum samples, prepared in a university-based andrology-IVF center, were included in the study. The frozen sera were thawed in batches to be used in a series of laboratory experiments. Serum quality was evaluated by spectrophotometric analysis and sperm bioassay under several defined conditions: fresh, frozen, pre- and postfiltration, pre- and postcentrifugation, and the patients' fertility condition. Although all sera were filtered through 0.22-micron filter, more than 10% frozen sera required 0.4- or a combination of 0.8- and 0.4-micron filters before they could be passed through the 0.22-micron filter. Frozen sera that were directly filtrable with a 0.22-micron filter lost 13% turbidity upon filtration. The turbidity of the frozen sera were higher compared to fresh ones as revealed by optical density (OD) and relative light scattering (RLS) spectrophotometry. The freeze/storage-induced spectrophotometric changes did not correlate with the storage time. The centrifugation caused precipitation of sera components. The rate of precipitation of the serum components correlated with the duration of freezing. Spectrophotometric analysis and sperm bioassay did not differentiate the sera of pregnancy-positive and pregnancy-negative subjects. The sperm bioassay failed to detect any biological impact of freezing-induced spectrophotometric changes in the sera, suggesting that the freezing-induced changes did not significantly diminish the serum's capability of supplementing the culture media.