Background: Semen ejaculates contain heterogeneous sperm populations that can jeopardize male fertility. Recent development of nanotechnology in physiological systems may have applications in reproductive biology. Here, we used magnetic nanoparticles as a novel strategy for sperm purification to improve semen fertility.
Methods: Boar semen was obtained in artificial insemination doses from a local boar stud. Doses were mixed with or without magnetic nanoparticles designed to target and deplete moribund and poor performing spermatozoa under an electromagnetic field. Sperm motility characteristics were assessed prior to insemination of open gilts with control (n=3 gilts) and nanopurified (n=4 gilts) semen. Pregnancies were verified 30 days post-insemination. Litter sizes and post-natal development of piglets were respectively evaluated at parturition and weekly until weaning.
Results: Nanopurification significantly improved sperm motility. Two gilts in the control group were confirmed nonpregnant, but the remainder maintained pregnancies through to parturition (33% vs. 100%, control and nanopurified groups, respectively). At parturition, the number of piglets born to the control gilt was not significantly different from the average of the nanopurified group (17 ± 0.0 vs. 15 ± 2, respectively; P>0.05); however, in the latter group 78% of piglets remained alive compared to 76% of the control. Birth weight of control piglets was lower (1.18 ± 0.22 kg) than those in the nanopurified group (1.41 ± 0.14 kg). Both groups of piglets showed linear and parallel growth rates with respective weight gains of 4.4x and 4.1x from birth to weaning. Interestingly, piglets produced in the nanopurified group comprised of 55% males compared to 38% in the control group.
Conclusions: Magnetic nanoparticles used in this preliminary study exhibited no toxic effects on sperm fertilization capacity and piglet viability. Beneficial effects may be seen in semen fertility, with possible use for gender selection. Further investigations on a large scale are needed to confirm the current findings, with potential application in clinical practice.