Effects of Semen Processing on Sperm Function: Differences between Swim-Up and Density Gradient Centrifugation

Abstract

Andrology research has evolved notoriously in the latest years, particularly since male factor contribution to couple infertility has been undoubtedly demonstrated. However, sperm function investigations results are sometimes contradictory, probably as a result of the use of different sperm processing techniques. In this work, we underwent a systematic functional comparison of human sperm samples simultaneously processed by swim-up and density gradient centrifugation, which are the preferred sperm processing methods used in basic and clinical laboratories. Materials and Methods: Materials and Methods: To compare functional characteristics of sperm isolated by swim-up and density gradient centrifugation followed by incubation at different times under capacitating conditions. Results: Results: Semen samples processed in parallel by these two procedures resulted in sperm preparations with significant differences in redox state, spontaneous intracellular calcium oscillations, hyperactivation, protein tyrosine phosphorylation, and acrosome reaction responsivity to calcium ionophore. Such differences showed time-dependent specific patterns for spontaneous intracellular calcium oscillations, hyperactivation and protein tyrosine phosphorylation. Sperm retrieved by density gradient centrifugation showed more hyperactivation and tyrosine phosphorylation than swim-up sperm, suggesting a higher degree of capacitation. Conclusions: Conclusions: Our results account for functional differences observed in spermatozoa processed with these two methods and therefore may contribute to a better interpretation of outcomes obtained in different laboratories as well as to improve experimental designs aimed to study sperm physiology and fertility potential.

Cumulative live birth rates after IVF/ICSI cycles with sperm prepared by density gradient centrifugation vs. swim-up: a retrospective study using a propensity score-matching analysis

“…This is consistent with a previous report by Van Der Zwalmen [ 29 ]. This finding may be explained by DGC’s selection of sperm with good capacitation and acrosome reaction abilities, which are key indicators of the ability of sperm to fertilize an egg [ 8 , 28 , 31 ]. That is, the DGC selects morphologically normal sperm cells, especially sperm with normal heads, based on their specific density.…”

“…That is, the DGC selects morphologically normal sperm cells, especially sperm with normal heads, based on their specific density. The sperm recovered by DGC thus have better acrosome function, capacitation, and sperm hyperactivation than those recovered by SU [ 8 , 28 , 31 ]. The resulting higher fertilization rate following DGC increases the number of available embryos and results in a better cLBR relative to SU.…”

“…In addition, only a few studies have evaluated other parameters that may affect IVF/ICSI outcomes. Some of these have reported that sperm prepared by DGC (vs. SU) have better acrosome function, capacitation, and hyper-activation [ 8 , 28 , 31 ], whereas others have found that sperm prepared by SU (vs. DGC) have fewer vacuoles in the heads [ 7 , 23 ].…”

Sperm Selection for ICSI: Do We Have a Winner?

“…Moreover, the latter is less efficient than SU in selecting sperm cells with intact DNA [ 66 ]. While these theories have been reinforced by more recent studies [ 67 ], in contrast, other authors have shown that DGC is better than SU to select a higher percentage of capacitated sperm [ 68 ] with hyper-activated motion even in cases of subfertility [ 69 ]. Other scientists suggest that neither method provides a cell population with acceptable levels of intact DNA.…”

High-throughput phenotypic screening of the human spermatozoon

“…An important issue in the advancement of andrology is a lack of consistency between research groups, and indeed clinics, in sperm handling techniques and in culture media composition. This may, in part, explain some of the uncertainty and conflicting literature in the field (Hernández-Silva, et al 2020). For example, recent work elucidating the mechanistic role of albumin in activating the proton channel hHv1 and capacitation of human sperm (Zhao, et al 2021) highlights the importance of sufficient levels of albumin in sperm culture media to fully support capacitation.…”