Anomalies in sperm chromatin packaging: implications for assisted reproduction techniques

Abstract

Sperm protamine deficiency and DNA damage were analysed employing chromomycin A 3 (CMA 3) staining and the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling assay, respectively, in 132 patients (82 IVF, 50 intracytoplasmic sperm injection [ICSI]). The antioxidant ability of seminal plasma was analysed in 10 men, using the total oxidant scavenging capacity assay. A significant negative correlation was found between abnormal protamination and sperm parameters, including sperm DNA fragmentation ( P < 0.01). A close relationship was found between sperm protamination and fertilization and pregnancy only in IVF ( P = 0.004 and P < 0.04, respectively); in ICSI there was a correlation between DNA fragmentation and pregnancy ( P = 0.031). Finally, there was a negative correlation between chromatin under-protamination and the antioxidant ability of seminal plasma ( P < 0.01). Results of this study underline that, despite sperm abnormal protamination and DNA fragmentation being positively correlated, they affect the reproductive outcome in different ways: in particular there was good prognostic value for CMA 3 analysis only in IVF, whereas DNA fragmentation analysis was prognostic only for ICSI outcome. Data are also provided to support the idea of a relationship between defective antioxidant system activity and impairment of chromatin packaging.