Experimental Studies on Sperm DNA Fragmentation and Reproductive Outcomes

Most of the assisted reproductive technologies (ARTs) overcome the selection of spermatozoa occurring within the female genital tract in mammals. This selection ensures the fertilization with spermatozoa containing chromatin of high integrity for supporting the ulterior embryo development. Consequently the use of nonselected spermatozoa porting fragmented DNA has been related to developmental and postnatal effects in animal models. The present chapter provides an overview on the implications of using sperm porting fragmented DNA in the reproductive outcome focusing in the knowledge acquired through experimentation in animal models. This is highly relevant given that intracytoplasmic sperm injection (ICSI) has been widely used in fertility treatments in humans. However, experimentation in mouse has demonstrated the risk of using DNA-fragmented spermatozoa in ICSI reducing the embryo and fetal performance as well as provoking long-term deleterious effects in the offspring at adulthood. In addition, the use of storage techniques for spermatozoa such as freezing-thawing and vitrification has been shown to increase the risk of fertilizing with fragmented DNA. Together with mammalian studies, the use of other nonmammalian animal models like fish could help in understanding the consequences of these treatments and to develop new strategies for sperm evaluation and selection before applying ARTs.