Sperm nuclear DNA damage and altered chromatin structure: effect on fertilization and embryo development

Abstract

In the first part of this report we investigate whether chromatin anomalies in human spermatozoa can influence fertilization after intracytoplasmic sperm injection (ICSI). We have examined the sperm chromatin packaging quality using the chromomycin A3 (CMA3) fluorochrome and the presence of DNA damage in spermatozoa using in-situ nick translation. When comparing the spermatozoa of patients undergoing in-vitro fertilization (IVF) and ICSI distinct differences are evident in that ICSI males have a higher CMA3 fluorescence, indicating spermatozoa with loosely packed chromatin, and more spermatozoa containing endogenous DNA nicks. When examining the unfertilized oocytes of ICSI patients we found that men who had a high percentage of anomalies in their chromatin, i.e. > 30% CMA3 fluorescence and > 10% nicks, had more than double the number of unfertilized oocytes containing spermatozoa that had remained condensed. The observation that failed fertilized oocytes, injected with spermatozoa from patients with a higher percentage of sperm nuclear anomalies, contain more condensed spermatozoa indicates that a selection process against these spermatozoa may be in place at the time of fertilization. In the second part of the study we show that spare ICSI embryos have significantly lower rates of development to the blastocyst stage compared with those developed after routine IVF. These results show that a greater understanding of the molecular basis of male infertility is therefore needed to broaden our knowledge on the effect that abnormal spermatozoa have on fertilization and embryo development.

Evaluation of sperm’s chromatin quality with acridine orange test, chromomycin A3 and aniline blue staining in couples with unexplained recurrent abortion

“…In some studies, CMA3 fluorochrome has been used to evaluate the sperm quality and fertilization capacity. Sakkas et al [27] found that men who had a high percentage of anomalies in their chromatin, i.e. >30% CMA3 fluorescence and >10% nicks, had more than double the number of unfertilized oocytes containing spermatozoa that had remained condensed.…”

Human Cervical Mucus Can Act in Vitro as a Selective Barrier Against Spermatozoa Carrying Fragmented Dna and Chromatin Structural Abnormalities

“…In this connection, it must be remembered that several studies have demonstrated that a variable but consistent fraction of human spermatozoa exhibits abnormalities in chromatin structure, not always detected using classical parameters of evaluation (12)(13)(14)(15)(16)(17)(18)(33)(34)(35). Moreover the existence of a close relationship between chromatin and DNA structural abnormalities and male infertility has been well pointed out.…”

“…During the last decade, a number of studies have shown that variable but consistent fractions of human spermatozoa not always detectable on the basis of classic morphological parameters, contain serious chromatin structural abnormalities and DNA strand breaks (12)(13)(14)(15)(16)(17)(18). The existence of an association between sperm chromatin malformation and male infertility has been repeatedly observed in humans and structural chromatin abnormalities have been found to exert negative effects both on the percentage of fertilization and on embryonic development (17,(19)(20)(21).…”

Future consequences and challenges for dairy cow production systems arising from climate change in Central Europe – a review

“…In all the studies, adverse effects on conventional sperm parameters and DNA integrity were documented (Karabinus et al, 1997). There is evidence that sperm with an impaired DNA integrity is capable of fertilizing oocytes, but the subsequent embryonic development is impaired (Sakkas et al, 1998;Larson et al, 2000). Setchell (1998) reported a decrease in fertilization rate of sheep ova obtained from abattoir and fertilized with sperm from scrotal-insulated rams.…”