DNA damage in human sperm: The sperm chromosome assay

Abstract

Background Sperm DNA damage is a major cause of pre‐ and post‐implantation embryonic loss in humans. However, the factors that control how and when such DNA damage occurs in human sperm are poorly understood. Methods Here, I review information relating to sperm DNA damage that can be obtained from the sperm chromosome assays described in the existing literature. Main findings The sperm chromosome assays, which consist of interspecific in vitro fertilization or intracytoplasmic sperm injection using murine oocytes and subsequent chromosome analysis, indicate that the proportion of sperm showing DNA damage is initially low and there are larger numbers of sperm with potential membrane and DNA damage that are induced after ejaculation and separation from the seminal plasma. Other assays that directly detect sperm DNA (e.g., TUNEL assays, Comet assays, and acridine orange test) are not able to distinguish and detect the initial and potential DNA damage. Furthermore, the positive values in these direct assays are influenced by the frequency of immotile sperm and amorphous sperm populations. Conclusion The findings in the sperm chromosome assays show that further improvements in sperm preparation protocols may result in the reduction of sperm DNA damage, followed by more successful outcomes in infertility treatment.

Assessing the Sperm Head DNA Damage in Frozen/Thawed Horse Semen via Interspecific ICSI

“…However, this method has much wider potential. Watanabe et al [12] used this approach as the human sperm chromosomes (DNA damage) assay. Specifically, he evaluated the sperm karyotypes in the first mitotic metaphases and found large numbers of abnormalities that cannot be detected with other methods like TUNEL, Comet assay or acridine orange test.…”

“…The interspecific ICSI is another possible approach that can be used when the number of spermatozoa is quite low or they are difficult to be isolated (i.e. from frozen sections or from permafrost cadavers) and also because the ovulated oocytes of given species are not readily available and if so, they must be typically matured in vitro and this decreases their quality [10][11][12]. Beside this, the ICSI approach does not work well in domestic animal (bovine, ovine, porcine, etc.)…”

“…It has been shown that after xenogenic ICSI the injected sperm heads decondense and form mPNs in which the level of DNA damage can be assessed by labeling the zygotes with anti-γH2AX antibody [10]. Moreover, the interspecific zygotes can be karyotyped during the first mitotic division where abnormal karyotypes also indicate DNA damage [12]. Also, the presence of micronuclei (MNs) as a relevant criterium can be used in the two-cell stage interspecific embryos as it has been shown that MNs are very frequent in embryos originating from oocytes fertilized with sperm with damaged DNA [14].…”

Effects of histones related to sperm chromatin on embryo development and ART outcomes

“…Many studies show sperm DNA damage affects fertilization rates, embryonic development quality, and pregnancy rates. [14,15] A study of the relationship between human sperm protamine, DNA damage, and assisted reproductive outcomes has shown that sperm DNA fragmentation is associated with abnormal protein binding and results in lower fertilization rates, lower embryo quality, and lower pregnancy rates. [12] Our results showed that sperm-nucleoprotein transition efficiency did not produce statistically significant differences among the indicators of IVF procedures.…”

Evaluation of in vitro fertilization outcome from very low sperm count and microdissection Testicular Sperm Extraction in patients with non-obstructive azoospermia: Paternal age factor

“…In patients with very few sperm in the ejaculate sample, there will be a high degree of DNA fragmentation, the percentage of dead sperm in the ejaculate sample is also very high. In addition, some studies have demonstrated that sperm from Cryptozoospermia samples have a higher DNA fragmentation index than sperm derived from testes (Watanabe, 2022). The study of Esteves et al (2015) (Esteves et al, 2015), when comparing the results of ICSI in the group using sperm derived from the testis and the group using sperm from the ejaculate sample with high DNA fragmentation index.…”