P–068 CatSper4 cation channel expression is low in male infertility and is affected by cryopreservation
Authors: Kilic N , İrez T , Dayiolu N 
Published: August 2021

Abstract

Study question
Is CatSper4 expression in sperm related to functional parameters and does cryopreservation affect CatSper4 expression?

Summary answer
In this study, it was aimed to investigate whether CatSper4 has a relationship with sperm parameters and is CatSper 4 affected by cryopreservation.

What is known already
CatSper membrane channels, known as cation channels, are thought to play an important role in the insufficiency of sperm physiology, acrosome reaction, and chemotaxis movement. There is no study on cation channel distribution in an infertile male patient. In addition, studies conducted in recent years have shown that cryopreservation techniques have negative effects on sperm DNA, but there is no analysis in the literature regarding the effects of cryopreservation on CatSper4 ion channel proteins.

Study design, size, duration
Samples of the patients who applied to the Andrology laboratory in the Medical Park Hospital IVF unit between March 1 and June 1 in 2020 were included in the study. Also, patients with no family history of no genetic anomalies , no varicocele and azoospermia were included.The study were divided into 4 groups in accordance with the male infertility guideline of the European Association of Urology as normozoospermic (control group), the asthenoteratozoospermia, teratozoospermia, and oligoastenotheratozoospermia.

Participants/materials, setting, methods
In this prospective study, semen analysis, DNA fragmentation, and CatSper 4 by IHC of control group patients with normospermia (n = 40) and oligospermia(n = 50), asthenospermia(n = 40), and teratozoospermia(n = 38) patients were compared and differences resulting from cryopreservation were evaluated by Wilcoxon signed Ranks Test.

Main results and the role of chance
It was observed that CatSper4 protein positivity was localized in the middle part of the sperm and it was statistically higher in the normozoospermic patient group compared to the other groups (p = 0,01). When the positivity values of CatSper4 protein before and after freezing were compared in the groups, it was seen that the values decreased (p = 0,001,p=0,01). Sperm DNA fragmentation was found to be lowest in normospermia and statistically significantly higher in other groups. Cryopreservation application increased DNA fragmentation in all groups (p &lt; 0,001 , p &lt; 0,01).

Limitations, reasons for caution
Unfortunately, embryo screening in patients with low CatSper4 expression is not available in the present study. Soon we plan to screen a broader clinical pregnancy series and present the IVF results associated with CatSper4.
Wider implications of the findings: Our study indicated that, CatSper4 expression is quite high in normospermia when compared with the other groups, particularly oligoasthenoteratozoospermia and asthenoteratozoospermia. There are almost no studies on this subject in the literature, and we think that it should be studied in larger patient groups and in unexplained infertile cases.

Trial registration number
Not applicable