Magnetic Beads Let Lab Sperm Reach Eggs but In-Vivo Tests Still Needed

Researchers attached about 30 iron oxide and polystyrene beads to the head of each cattle sperm cell, allowing the cells to be moved and guided by external magnetic fields while their tails moved freely. The attached beads did not alter swimming speed or overall health of the sperm. The magnetic sperm formed healthy embryos when incubated with eggs in a dish at the same rate as ordinary sperm.

The beads detached as the sperm penetrated the egg and did not interfere with early embryo development. An external magnetic field guided the magnetic sperm in chosen directions and toward eggs in laboratory dishes. The beads are visible on ultrasound, which would permit tracking inside the body.

Mariana Medina-Sánchez at CIC nanoGUNE in Spain led the work. “Our ultimate idea is to do assisted reproduction in vivo, taking advantage of the body as a natural incubator,” she said. ” Dunning noted that further tests are required to show whether magnetic sperm can be directed into fallopian tubes, fertilise eggs, implant in the endometrium, and yield live healthy offspring.

Medina-Sánchez said the beads should be cleared naturally once they fall off, or removed by magnets attached to catheters if needed. Separate unpublished work showed whole embryos placed inside tiny magnetic structures could be guided into mouse fallopian tubes with external magnets. 720095.