Effects of cryopreservation on plasma membrane glycoconjugates of human spermatozoa

Background: Cryopreservation has some detrimental impacts on sperms surface molecules. Modification of the sperm surface molecules can affect on fertility rate. One of the important surface molecules are glycoconjugates. Objective: The objective of this study was to evaluate the changes of content of the glycocalyx after standard cryopreservation procedure. Materials and Methods: Forty five healthy semen samples were frozen in 0.5ml plastic straws and kept in liquid nitrogen and thaw after 48 hours. Sperm smears were prepared before and after freezing and thawing. The smears were stained with the lectins and also with acridin orange. The smears were studied by fluorescents microscopy and the intensities of the reactions to lectins were measured by image analyses software. Results: The reactions of the sperm samples to Peanut agglutinin (PNA), Wheat germ agglutinin (WGA) and Dolichos biflorus (DBA) changed after cryopreservation and the percentage of samples that showed modifications were 46.67%, 34.09% and 73.34%, respectively. The crypreservation led to both increase and decrease the intensities of the reactions. It means that there are various mechanisms that impact on the carbohydrate contents of the sperm surface. There is no correlation between DNA denaturation of sperms and their lectin binding patterns. Conclusion: Cryopreservation affected the surface glycoconjugates at least in a subset of spermatozoa. These results might cause to modify the future application of sperm banking techniques.