Effect of prepared and unprepared semen on sperm quality of vitrified normozoospermia

Abstract

Introduction: Sperm cryopreservation by vitrification is process to preserve sperm for fertility treatment. However, from previous studies, after freezing and thawing, there are some disadvantages i.e. decreased sperm concentration and motility while increasing sperm DNA fragmentation. Thus, we were interested to study the protective effects of prepared and unprepared semen on sperm quality after freezing and thawing of vitrified normozoospermia.

Method: Semen samples collected from 40 normospermic male volunteers (according to WHO criteria 2010) were divided into 4 groups as the followings; group 1: unprepared or neat semen, group 2: prepared semen, group 3: unprepared semen, frozen and thawed, group 4: prepared semen, frozen and thawed. Semen quality of these 4 groups i.e. sperm concentration, morphology and motility were compared. Also, sperm vitality measured by Hypo-osmotic swelling test (HOS), sperm maturity and functions measured by Hyaluronan binding assay (HBA) and sperm DNA damage measured by Comet assay were performed.

Result: After sperm preparation, sperm concentration and DNA damage were significantly decreased whereas sperm motility, progressive motile sperm, sperm with normal morphology, sperm vitality, sperm maturity and functions were significantly increased compared to those of fresh unprepared sperm. After freezing and thawing of prepared and unprepared sperm, almost all sperm parameters of both groups were decreased except DNA damage which was significantly increased. However, the percentage of normal morphology sperm was significantly higher while sperm DNA damage and sperm vitality were significantly lower in the prepared sperm group.

Discussion and Conclusion: This study revealed that sperm preparation was able to improve all parameters of sperm quality (except sperm concentration) including sperm maturation and functions and sperm DNA damage but could not do so after freezing and thawing. Anyway, sperm preparation before freezing and thawing by vitrification resulted in higher percentage of normal morphology sperm with lesser degree of DNA fragmentation and vitality than those of the unprepared group. These findings may be beneficial for clinical application in the treatment process of infertility. Anyhow, further investigations are still needed for larger scale of data.

Key words: Sperm preparation, Vitrification, Semen analysis, Sperm hyaluronan binding assay, Sperm DNA fragmentation