Low-level laser therapy appears to improve sperm motility parameters in a dose-dependent manner.

SAN FRANCISCO—Low-level laser therapy (LLLT) may perk up sperm and improve fertility rates, according to a newly released study.

Laser treatment of prepared substandard sperm prior to intrauterine insemination (IUI) or in vitro fertilization (IVF) may yield improved assisted reproductive technology results, Australian researchers reported here at the annual meeting of the American Society for Reproductive Medicine. In addition, laser therapy may be beneficial for in vivo direct testicular treatment of men with substandard semen.

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There is considerable published literature detailing the photobiomodulation effects on human tissue of LLLT from both laser and light-emitting diode (LED) sources at wavelengths from 630 to 1,000 nm. Few data exist regarding their effect on spermatozoa, however.

LLLT has been shown to help temporarily improve canine sperm motility, increase calcium transport within murine spermatozoa, and increase the longevity of motility in previously frozen turkey sperm. To investigate the effect of LLLT on human sperm, Australian researchers conducted a prospective observational study on normospermic and asthenospermic semen specimens.

Four human semen specimens were subjected to LLLT from two continuous-output sources at varying distances. The researchers compared the sperm motility index (SMI) and total functional sperm count (TFSC) parameters across a range of calculated light doses from each source. Two experiments were conducted utilizing fresh normal and fresh asthenospermic semen specimens.

Compared with controls, SMI and TFSC in light-exposed samples were increased up to fourfold for normal semen and sevenfold for asthenospermic semen, with an inhibitory effect at higher doses. Maximum effect and timing post-exposure varied with the light source. The maximum effect on normal semen was achieved at 30 minutes post-exposure for the lowest dose of the LED cluster and at 15 minutes post-exposure to the intermediate doses for the laser diode.

For the asthenospermic semen, the maximum effect came from the mid-range doses at 30 minutes post-exposure for the LED cluster and from the lowest laser dose at 30 minutes post-exposure. There was no apparent effect of LLLT on sperm DNA integrity.

“The improvement in sperm motility is largely [attributed] to a freeing up of chemical pathways within the sperm or within the cells, [resulting in a release of] energy from the mitochondria and just causing them to do their job better and quicker,” said study investigator Keith Harrison, PhD, scientific director of Queensland Fertility Group, in Brisbane.

LLLT appears to improve sperm motility parameters in a dose-dependent manner, he said. The effect may be at the expense of motility longevity, however. Laser and LED light appear to yield similar effects.

“It may be possible to treat men with marginal sperm and allow couples to avoid IVF and just go to the simpler procedures, such as intrauterine insemination,” Dr. Harrison told Renal & Urology News. “We may have a new mechanism and process to treat men whose testes produce substandard sperm. We hope to shine a bright red light on the testes and stimulate production or [improve the quality] of sperm.”