Effects of Pulsed-Wave Photobiomodulation Therapy on Human Spermatozoa.

BACKGROUND AND OBJECTIVES

Previous studies reported that photobiomodulation (PBM) positively affects the mitochondrial respiratory chain in sperm, resulting in improved motility and velocity. As laser settings are not yet fully established, the present study aimed at optimizing PBM on human sperm. In addition, possible side-effects of PBM on sperm DNA fragmentation level and acrosomal integrity have been analyzed.

STUDY DESIGN/MATERIALS AND METHODS: A pulsed laser-probe (wavelength 655 nm, output power 25 mW/cm², impulse duration 200 nanoseconds) was used. Native fresh liquefied semen samples underwent radiation with energy doses of 0 (control), 4, 6, and 10 J/cm². Sperm parameters were assessed at 0, 30, 60, 90, and 120 minutes after radiation using a computer-assisted sperm analysis system. Motility and velocity of sperm from asthenozoospermic patients (n = 42) and normozoospermic controls (n = 22) were measured. The amount of DNA strand breaks was analyzed using ligation-mediated quantitative polymerase chain reaction in patients with asthenozoospermia (n = 18) and normozoospermia (n = 13). Post-irradiance acrosomal integrity was investigated using flow cytometry based on CD46 protein expression (n = 7).

RESULTS

Exposure to laser energy-doses of 4 and 6 J/cm² improved sperm motility and velocity in asthenozoospermic patients. PBM exhibited no significant effect on DNA fragmentation level and expression of CD46 serving as a biomarker for acrosome integrity.

CONCLUSION

PBM improves sperm motility parameters by maintaining DNA and acrosome integrity and, therefore, represents a promising new tool for assisted reproductive therapy. In particular, improving sperm motility in asthenozoospermic patients by PBM in future may contribute to increasing the chance for successful intrauterine insemination. The present trial has no clinical registration number, as only in vitro studies were performed. The study was approved by the local ethics committee and performed according to the Declaration of Helsinki. Lasers Surg. Med. © 2021 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.