Chymotrypsin effects on the determination of sperm parameters and seminal biochemistry markers

Effect of mild α-chymotrypsin treatment of highly viscous semen samples on fertilization rates

Background

Highly viscous semen reduces sperm motility significantly and can contribute to infertility. When processing semen samples, few techniques exist to induce liquefaction in case of seminal hyperviscosity such as different washing steps and mechanical treatment. The use of α-chymotrypsin seems controversial due to possible negative effects on fertilisation rates after in vitro fertilization (IVF). The main objective of this study was to examine the influence of mild α-chymotrypsin treatment of semen samples on the fertilisation rate after artificial reproductive treatment (ART).

Methods

The fertilization rate of 52 ART cycles was examined following IVF using a low dose of α-chymotrypsin to induce liquefaction of highly viscous semen and was compared to a control group of 88 ART cycles.

Results

There was no significant difference in the fertilization rates of α-chymotrypsin treated semen samples compared to the control group; pregnancy rates were unaffected.

Conclusions

The use of mild α-chymotrypsin treatment of semen samples in case of hyperviscosity does not appear to impact negatively on the fertilization rates after ART and could be regarded as an additional method to induce liquefaction of highly viscous semen samples in IVF.

Treatment of semen samples with α-chymotrypsin alters the expression pattern of sperm functional proteins-a pilot study

Semen hyperviscosity delays the liquefaction of semen sample and is subjected to limited proteolysis by addition of α-chymotrypsin to reduce the viscosity. α-Chymotrypsin is a proteolytic enzyme involved in degradation of the proteins and polypeptides. Even though α-chymotrypsin improves the handling of hyperviscous samples, its effect on the sperm proteins is not clear. This study was aimed to evaluate the alteration in the expression of sperm functional proteins in samples treated with α-chymotrypsin. Among all the proteins examined in both donor and patient samples, HSPA2 (70 KDa), BAG6 (150 KDa), HIST1H2BA (14 KDa), SPA17 (17 KDa formed after cleavage of C-terminal calmodulin-binding domain), and OXPHOS complexes were undetectable in α-chymotrypsin-treated samples, while the expression of the native SPA17 (20 KDa) was significantly decreased in the α-chymotrypsin-treated samples in comparison with controls. The use of α-chymotrypsin for liquefaction of hyperviscous samples degrades functional proteins of spermatozoa. Intracellular proteins, such as OXPHOS complexes and HIST1H2BA, and sperm surface proteins (HSPA2, BAG6, and SPA17) were degraded in all treated samples. Whether treatment of samples with α-chymotrypsin affects the global proteomic outcome is unclear. More in-depth calibration studies are required to determine the appropriate concentration of α-chymotrypsin for processing hyperviscous semen samples without compromising its protein expression and function. Similarly, the effects of altered protein function on assisted reproductive techniques (ART), such as intrauterine insemination (IUI) and in vitro fertilization (IVF) outcome, are not known and require further research.

Validation of a laboratory-developed test of human sperm capacitation

Sperm must undergo capacitation to become fertilization competent. Here we validated that monosialotetrahexosylganglioside (GM1 ) localization patterns, which were assessed in the Cap-Score™ Sperm Function Test, reflect a capacitated state in human sperm. First, we defined patterns representing sperm that do or do not respond to stimuli for capacitation. Sperm with "capacitated" patterns had exposed acrosomal carbohydrates and underwent acrosome exocytosis in response to calcium ionophore (A23187). Precision was evaluated by percent change of the Cap-Score measured for 50, 100, 150, and 200 sperm. Changes of 11%, 6%, and 5% were observed (n ≥ 23); therefore, we counted ≥150 sperm per condition. Variance within and between readers was evaluated using 20 stitched image files generated from unique ejaculates. Two trained readers randomly resampled each image 20 times, reporting an average standard deviation of 3 Cap-Score units and coefficient of variation of 13% when rescoring samples, with no difference between readers. Semen liquefaction times ≤2 hr and mechanical liquefaction with Pasteur or wide-orifice transfer pipettes did not alter Cap-Score values. However, liquefaction with chymotrypsin (p = 0.002) and bromelain (p = 0.049) reduced response to capacitating stimuli and induced membrane damage, while counterintuitively improving sperm motility. Together, these data validate the Cap-Score assay for the intended purpose of providing information on sperm capacitation and male fertility. In addition to its clinical utility as a diagnostic tool, this test of sperm function can reveal the impact of common practices of semen handling on the ability of sperm to respond to capacitation stimuli.

A Pilot Comparative Study of 26 Biochemical Markers in Seminal Plasma and Serum in Infertile Men

Introduction. The relationships of the biochemical components in seminal plasma and serum, and their origins and physiological effects in male reproductive system have been poorly understood. Methods. Based on the calibration and quality control measures, 26 biochemical markers, in seminal plasma and serum samples from 36 male infertility patients with nonazoospermia were detected and compared. Results. Only PA was undetectable in all seminal plasma samples. There were significant differences of all other 24 biochemical markers in seminal plasma and serum (P < 0.05) except for UA (P = 0.214). There were rich proteins in seminal plasma, and globulin accounted for about 90%. There were also abundant enzymes in seminal plasma, and the activities of ALT, AST, AKP, GGT, LDH, CK, and αHBDH in seminal plasma were significantly higher than those in serum while ADA was inversely lower. There were relatively low levels of Glu, TG, TC, and hsCRP in seminal plasma, but Glu was undetectable in 8 of 36 cases. Conclusions. The differences of the levels of biochemical markers in seminal plasma and serum might be associated with the selective secretion of testis, epididymis and male accessory glands, and the specific environment needed for sperm metabolism and function maintenance.

A survey on the status of semen analysis in 118 laboratories in China

Collecting baseline information on how laboratories perform testing is a reasonable first step towards establishing intra- and inter-laboratory standardization and quality control for semen analysis. We carried out a survey of the laboratories performing the testing in Mainland China. A questionnaire, composed of 36 questions covering all aspects of semen analysis, was designed, and a copy was distributed to each of the 145 laboratories. Of these, 118 laboratories completed the questionnaires. The survey results showed that semen volume was measured visually in 53.6% (59/110) of the responding laboratories, and 70.9% (73/103) of laboratories analysed incompletely liquefied semen without any treatment. In addition, both manual-microscopic and computer-assisted semen-analysis systems were applied to analyse sperm concentration, motility and morphology. However, more than five methods were employed in routine sperm staining. An enzyme-linked immunosorbent assay was commonly used for determining whether antisperm antibodies were present. Several seminal biochemical markers were analysed in only 27.1% (32/118) of the responding laboratories. Generally, there was a lack of intra- and inter-laboratory quality control measures for semen analysis in all laboratories responding to this survey. In conclusion, the methods of semen analysis and the interpretation of test results in the surveyed laboratories differed markedly. In particular, many laboratories employed methods other than those recommended by the World Health Organization Laboratory Manual for the Examination of Human Semen and Spermcervical Mucus Interaction (1999). These findings suggest an urgent need for the standardization of semen analysis with acceptable quality controls for each parameter to make the results repeatable and meaningful.