P-089 Sperm motility and sperm DNA fragmentation evaluation after irradiation with a 633nm He-Ne laser in donor samples. An in vitro pilot study
Authors: Aguilar Prieto J , Stefano C , Pablo B , Pio G , Esther T , Elkin M 
Published: July 2024

Abstract

Study question
Does a 633nm laser irradiation on sperm samples improve sperm motility safely?

Summary answer
633 nm wavelength He-Ne laser irradiation for 5 and 10 minutes increases slow progressive and non-progressive sperm motility without modification of the DNA fragmentation.

What is known already
Sperm motility has been hypothesized to increase after light radiation excitation of cytochrome c- oxidase, which boost adenosin triphosphate (ATP) synthesis, in a range of wavelength between 600-1000 nm. One of the main problems of this stimulation is the generation of Reactive Oxigen Species (ROS) that may affect sperm DNA integrity. Previous studies have approached to this field showing different results.

Study design, size, duration
In vitro pilot study of 15 sperm samples donated for research between June 2022 and October 2023 which were irradiated with a 633nm wavelength He-Ne laser. Each sample was split in 4 aliquots of 10 microliters. To study sperm motility analysis, two videos of each were recorded, before and after irradiation, anonymized and evaluated later by a single embryologist. Sperm motility was annotated according to WHO 2021 criteria.

Participants/materials, setting, methods
After laser calibration and alignment, sperm samples were irradiated at 37 ºC in a Makler chamber with a continuous emission laser with a gaussian-like beam thirty cm. away for 5,10,15 and 20 minutes. Two videos were obtained for each aliquot, before and after irradiation. Radiant exposure was calculated using the equation y = 1030 x-1,626. Sperm Chromatine Dispersion (SCD) test was employed in 50 µl aliquots to study DNA fragmentation.
Shapiro-Wilk and paired t-student tests were employed.

Main results and the role of chance
We observed a significant increase in slowly progressive motility; -0.075 [-0.12 – 0.024] (p = 0.007); and non-progressive motility; -0.023 [-0.041 – -0.006] (p = 0.011); after irradiating samples between 5 and 10 minutes with a total radiant exposure, 0.4830 and 0.9661 (mW/mm2 * min). Also, for total progressive motility; -0.075 [-0.13 – -0.01] (p = 0.024), and total motility; -0.069 [-0.126 – -0.012) (p = 0.021).
No differences were found in sperm DNA fragmentation index after irradiating for 10 minutes; -1.347 [-4.073 - 1.380] (p = 0.32) nor for 20 minutes of irradiation -1.587 [-4.400 - 1.227] (p = 0.25).
According to our results, irradiation of sperm samples between 5 and 10 minutes with a 633nm wavelength laser, increases type b and type c motility spermatozoa without affecting sperm DNA fragmentation. Longer irradiations, 15 and 20 minutes, do not show an improvement in sperm motility, neither in sperm DNA fragmentation in our set of data.

Limitations, reasons for caution
This in vitro pilot study has not been proved in samples to clinical use and our findings need a confirmation with clinical samples in animals to ensure the safety in the conceptions and offspring. We included samples with normal sperm values. Results should be confirmed in samples with motility defects.

Wider implications of the findings
Our findings are the first step in a new way to modify the sperm motility in vitro throughout laser exposition, which may benefit patients with severe asthenozoospermia without the use of chemical motility inductors. We hope to confirm the safe clinical use in animals before translation to humans.

Trial registration number
1909-VGO-082-JA