Give sperm a ‘kick’ to make it fertile

CARDIFF U. (UK) — Adding a missing protein to infertile human sperm can increase its ability to fertilize an egg, dramatically increasing the chances of a successful pregnancy.

Sperm transfers a vital protein—called PLC-zeta (PLCz)—to the egg upon fertilization. The protein initiates egg activation, which sets off all the biological processes necessary for the development of an embryo.

Researchers have discovered that eggs that don’t fertilize because of a defective PLCz can be treated with the active protein to jumpstart the fertilization process.


“We know that some men are infertile because their sperm fail to activate eggs. Even though their sperm fuses with the egg, nothing happens. These sperm may lack a proper functioning version of PLCz, which is essential to trigger the next stage in becoming pregnant,” says Tony Lai, professor at Cardiff University.

“What’s important from our research is that we have used human sperm PLCz to obtain the positive results that we had previously observed only in experiments with mice.

“In the lab we have been able to prepare human PLCz protein that is active. If this protein is inactive or missing from sperm, it fails to trigger the process necessary for egg activation—the next crucial stage of embryo development.

“However, when an unfertilized egg is injected with human PLCz, it responds exactly as it should do at fertilization, resulting in successful embryo development to the blastocyst stage, vital to pregnancy success,” he adds.

The study is published online today in the journal Fertility and Sterility and is funded by the Wellcome Trust.

“Whilst this was a lab experiment and our method could not be used in a fertility clinic in exactly the same way—there is potential to translate this advance into humans,” says Lai.

“In the future, we could produce the human PLCz protein and use it to stimulate egg activation in a completely natural way. For those couples going through IVF treatment, it could ultimately improve their chances of having a baby and treat male infertility.”

Source: Cardiff University