Exposing human sperm cells to a shining red light improves their performance, says a new study.
The researchers also discovered that human sperm cells live longer and move more efficiently on diamond surfaces compared with traditional polystyrene petri dishes.
A combination of diamond-coated petri dishes and exposure to near-infrared light is best for women looking to become pregnant through in vitro fertilisation (IVF).
During IVF, sperm is introduced to an egg in the petri dish. If the egg is successfully fertilised, the resulting zygote is implanted into the woman’s uterus.
The findings of the study titled Diamond dishes could boost IVF success rates was released late last month in the journal Science.
Sperm, like most cells, exude harmful, cell-disrupting molecules known as reactive oxygen species (ROS).
Inside the body, these ROS last only a fraction of a second and are quickly neutralised as they bind with nearby molecules. But polystyrene naturally forms a thin, gluelike nano-layer of water on its surface, which traps the ROS.
“The sperm is stewing in its own ROS,” says Andrei Sommer, a scientist who led the study while working at Ulm University in Germany.
“This longer exposure is highly, highly, highly destructive to the cell.”
The upshot is that many sperm cells exposed to polystyrene quickly lose their motility, turning into moving cells incapable of fertilising an egg.
“The more highly motile sperm cells a sample contains, the more likely it is that an IVF procedure will result in pregnancy, though a host of other factors like sperm count and egg quality also play a role,” he says.
The researchers also wondered whether keeping sperm cells on a material like diamond, which forms a slick, not sticky, surface layer of water, would protect them from ROS. The researchers coated quartz petri dishes with a superthin layer of diamond and placed human sperm cells on them.
They assigned the cells one of four grades ranging from A which were marked rapidly moving and the most likely to fertilise to D, which were completely immobile and incapable of fertilisation.
Then they did the same thing for sperm cells taken from the same sample but placed on traditional polystyrene petri dishes.
“After an hour, the diamond-coated petri dishes contained 300 per cent more Grade A sperm cells than did the polystyrene dishes,” the team reports in the Annals of Translational Medicine.
“That’s likely because ROS can’t stick to the diamond surface in the same way that they do to polystyrene, Sommer says.
“The ROS, when landing on diamond, have no chance to harm the cells.”
In a separate set of experiments, the team tested how light affects sperm cells.
When the researchers exposed sperm cells to this wavelength, they found about twice as many Grade A cells after 30 minutes than were in control groups.
“Used in conjunction, diamond-coated petri dishes and near-infrared light might make sperm cells intended for IVF procedures more energetic and longer lasting, increasing the chance of a successful fertilization,” Sommer says,
However, he says more testing is needed before any of these techniques could be used in the clinic.
He said the disadvantage of the diamond dishes, is that they are very expensive than the plastic dishes.
“It costs about $100 to make a diamond-coated petri dish like the one used in the study compared with polystyrene dishes that cost mere pennies,” he said.