Comparative analysis of human sperm glycocalyx from different freezability ejaculates by lectin microarray and identification of ABA as sperm freezability biomarker.

BACKGROUND: Semen cryopreservation has been widely applied in assisted reproductive technologies and sperm bank, but it causes considerable impairments on sperm quality. It is necessary to find an evaluation indicator for determining the sperm-freezing tolerance. METHODS: The glycocalyx of good freezability ejaculates was compared with poor freezability ejaculates by lectin microarray. The significant different lectins were validated by flow cytometry (FACS). To analyze the relationship between the potential biomarker and the tolerance of sperm to cryopreservation, 60 samples with different recovery rates were collected and detected the lectin-binding intensity by FACS. The receiver operating characteristic (ROC) curve was analyzed to test the capability of the lectin as a potential biomarker for detecting the sperm freezablility. RESULTS: ABA and DSL were found to develop significant differences between them. Further validation showed that ABA was significantly negative correlated with the sperm recovery rates (r = - 0.618, P < 0.000) and could be a potential biomarker for predicting sperm freezability (AUC = 0.733 ± 0.067, 95% CI 0.601 - 0.865, P < 0.01). CONCLUSION: ABA could be a potential biomarker for predicting sperm freezability. It will help to reduce sperm-freezing recovery tests and improve the efficiency of cryopreservation in human sperm bank.

Comprehensive profiling of accessible surface glycans of mammalian sperm using a lectin microarray.

It is well known that cell surface glycans or glycocalyx play important roles in sperm motility, maturation and fertilization. A comprehensive profile of the sperm surface glycans will greatly facilitate both basic research (sperm glycobiology) and clinical studies, such as diagnostics of infertility. As a group of natural glycan binders, lectin is an ideal tool for cell surface glycan profiling. However, because of the lack of effective technology, only a few lectins have been tested for lectin-sperm binding profiles. To address this challenge, we have developed a procedure for high-throughput probing of mammalian sperm with 91 lectins on lectin microarrays. Normal sperm from human, boar, bull, goat and rabbit were collected and analyzed on the lectin microarrays. Positive bindings of a set of ~50 lectins were observed for all the sperm of 5 species, which indicated a wide range of glycans are on the surface of mammalian sperm. Species specific lectin bindings were also observed. Clustering analysis revealed that the distances of the five species according to the lectin binding profiles are consistent with that of the genome sequence based phylogenetic tree except for rabbit. The procedure that we established in this study could be generally applicable for sperm from other species or defect sperm from the same species. We believe the lectin binding profiles of the mammalian sperm that we established in this study are valuable for both basic research and clinical studies.

Sperm-specific protein ACTL7A as a biomarker for fertilization outcomes of assisted reproductive technology.

Obtaining high-quality embryos is one of the key factors to improve the clinical pregnancy rate of assisted reproductive technologies (ART). So far, the clinical evaluation of embryo quality depends on embryo morphology. However, the clinical pregnancy rate is still low. Therefore, new indicators are needed to further improve the evaluation of embryo quality. Several studies have shown that the decrease of sperm-specific protein actin-like 7A (ACTL7A) leaded to low fertilization rate, poor embryo development, and even infertility. The aim of this study was to study whether the different expression levels of ACTL7A on sperm can be used as a biomarker for predicting embryo quality. In this study, excluding the factors of severe female infertility, a total of 281 sperm samples were collected to compare the ACTL7A expression levels of sperms with high and low effective embryo rates and analyze the correlation between protein levels and in-vitro fertilization (IVF) laboratory outcomes. Our results indicated that the ACTL7A levels were significantly reduced in sperm samples presenting poor embryo quality. Furthermore, the protein levels showed a significant correlation with fertilization outcomes of ART. ACTL7A has the potential to be a biomarker for predicting success rate of fertilization and effective embryo and the possibility of embryo arrest. In conclusion, sperm-specific protein ACTL7A has a strong correlation with IVF laboratory outcomes and plays important roles in fertilization and embryo development.