Cryopreservation and Sperm DNA Integrity

Abstract

Cryopreservation of sperm is an extremely important issue in the field of male infertility as freezing can have detrimental effects on a variety of sperm functions, some of them not accessible to the traditional semen quality analysis. In this study, chromatin structure variations in human spermatozoa in semen were studied with the sperm chromatin structure assay (SCSA), both before and after cryopreservation. Samples were divided into two aliquots: the first was analysed without further treatment, while the second was stored in liquid nitrogen at -196 degrees C using standard cryopreservation techniques. The fresh and thawed aliquots were also assessed by light and fluorescence microscopy (after Acridine Orange staining, AO), and computer-assisted semen analysis (CASA) of motility. Overall sperm quality was found to deteriorate after cryopreservation. When thawed spermatozoa were subjected to an extra swim-up round, a general improvement in nuclear maturity was seen in post-rise spermatozoa.

Routine cryopreservation of spermatozoa is safe — Evidence from the DNA methylation pattern of nine spermatozoa genes

“…Our study confirmed that DNA fragmentation is increased after cryopreservation as previously described [8,12,42]. However, we also noted that the DNA fragmentation in "swim-up"purified samples is higher following short-term than after longer cryopreservation.…”

“…Current cryopreservation protocols involve the freezing of the ejaculate with cryoprotectants which when thawed are "swim-up" purified for use in ART. Previously, it has been described that cryopreservation causes DNA fragmentation in spermatozoa [8,12,42]. In particular, the effect of cryopreservation and thawing on DNA integrity was greater in infertile men than in fertile men [4,12].…”

Effect of sperm storage and selection techniques on sperm parameters

“…This loss in sperm quality is especially significant in patients whose sperm parameters are poor to begin with [Hammadeh et al 1999;McLaughlin et al 1992]. Motility is the most affected parameter [Donnelly et al 2001a;Gandini et al 2006]. O'Connell et al [2002] proposed that the decrease in sperm motility is due to mitochondrial damage and physical changes to the sperm tail.…”

“…The packaging of DNA in a sperm nucleus follows a long process that begins in spermiogenesis where the histones are replaced by protamines [Boissonneault 2002]. The integrity of spermatozoa seems to be the determining factor in the success of fertilization in both natural and assisted reproductive methods [Gandini et al 2006]. It has been noted that the decrease in post-thaw quality is mostly due to DNA fragmentation that occurs after cryopreservation.…”

Sperm DNA fragmentation in cryopreserved samples from subjects with different cancers

“…All subjects were asked to observe 2-7 days of sexual abstinence prior to sample collection. After semen analysis, semen samples were frozen in liquid nitrogen tanks using a manually controlled freezing procedure as described by Gandini et al (2006) with minor modifications. Briefly, samples were diluted 1 : 1 (v/v) by drop-wise addition of test yolk buffer with glycerol and gentamicin (Irvine Scientific, Santa Ana, CA, USA).…”