As the average age at which individuals marry continues to rise amid a declining birth trend, male fertility is gaining increasing attention alongside female fertility. According to medical experts, a critical factor in male fertility is sperm motility. When sperm motility is low, sperm cannot move efficiently, reducing the likelihood of fertilizing an egg. Conversely, more sperm exhibiting high motility increases the chances of successful fertilization.
A research team at Monash University in Australia, led by Professor Adrian Neild from the Department of Mechanical and Aerospace Engineering, recently published research results in the international journal “Science Advances.” The study proposed a rapid and noninvasive approach to enhance the motility and swimming velocity of human sperm cells using ultrasound. The research showed up to 266% improvement in motility for relatively immotile sperm. The team anticipates that these promising results will enhance assisted reproduction outcomes for infertile male patients.
Common methods for improving fertility in males with low sperm motility include quitting smoking, maintaining a healthy BMI, and engaging in regular exercise. More aggressive treatments may involve drugs and hormone therapy. Pentoxifylline is a representative drug known to enhance sperm quality and motility, but reports indicate potential harmful effects such as DNA damage. Hormone therapy for male infertility must be cautiously employed, as it may lead to the inhibition of sperm production or aspermia. Hence, there is a growing demand for noninvasive treatments.
The research team utilized sperm donated from three healthy males aged from 20 to 40, each with 20 to 40 million sperm per mL, falling within the normal range. Males with less than 15 million sperm per mL are considered to have low fertility.
To track and analyze sperm motility overtime at the single-cell level, the research team employed a “droplet-based microfluidic technique.” This method involves using two non-mixing fluids to separate microfluids, allowing for rapid research of bodily reactions in a short timeframe. Individual nonprogressive or immotile sperm cells were encapsulated in microdroplets and exposed to high-frequency ultrasound to examine any changes in sperm motility based on the droplet-based microfluidic technique.
The findings indicated that ultrasound exposure significantly enhanced sperm motility and swimming velocity. Specifically, there was a notable increase of up to 266% in sperm motility, with 34% of initially immotile sperm demonstrating full motility upon exposure to ultrasound.
Generally, sperm motility significantly decreases in men aged over 45. A study from the Gangnam Cha Hospital Andrology Department, published by the Korean Urological Association Journal, revealed that middle-aged males exhibited 11% lower sperm motility than their younger counterparts. This emphasizes the importance of considering both the age of the woman and the man when planning to have a child. “While there is a need for a biocompatible and noninvasive treatment method, we have proposed the ultrasound approach,” the Australian research team stated. “This research confirms that ultrasound offers promising results in assisted reproduction.”
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