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13 May 2010: The Times (London)

From The Times
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May 13, 2010

Scientists find new role for ultrasound — as a male contraceptive

Hannah Devlin

A one-off blast of ultrasound could work as a reversible contraceptive for men, according to scientists.

If preliminary results are confirmed, applying therapeutic ultrasound to the testes for ten to fifteen minutes could be provide protection for up to six months.

James Tsuruta, of the University of North Carolina, who led the research, said: “We think this could provide men with reliable, low-cost, non-hormonal contraception from a single round of treatment.”

Dr Tsuruta and colleagues have already proved the technique in rats, and plan to extend trials to humans as early as next year. Their findings so far suggest that sperm production can be halted temporarily without causing a longer-term reduction in fertility.

Once sperm production resumed after six months there was no evidence of complications, such as sperm being of lower genetic quality.

The intensity of ultrasound required would be similar to that used to break down scar tissue after a sprained ankle, for instance. “Our long-term goal is to use ultrasound from therapeutic instruments that are commonly found in sports medicine clinics as an inexpensive, long-term, reversible male contraceptive.”

Ultrasound was tested briefly in prostate cancer patients in the 1970s, who described the treatment as painless and producing a gentle warming sensation. “It would be like sitting in a mini hot tub once every six months,” said Dr Tsuruta.

The team of researchers has been awarded $100,000 (£67,000) from the Bill & Melinda Gates Foundation to prepare for a trial in humans. The first step is to establish the minimum intensity of ultrasound required to act as a contraceptive in rats. The team also plan to investigate the mechanism that causes temporary infertility.

“Establishing safety, efficacy and reversibility: these are our top concerns,” said Dr Tsuruta.

Ultrasound produces a mild heating that appears to disable sperm cells and deplete the supply of stem cells that are required to replenish sperm reserves in the testes. Post-treatment images of the rat testes showed the tubules inside the testes completely lacking in sperm with almost no immature stem cells.

It normally takes about two months for stem cells to develop into functional sperm and it is unclear why the contraceptive effect lasts longer than this.

One possibility is that testes have a self-regulating mechanism that causes stem cells to divide and multiply rather than specialising into sperm cells when supplies of stem cells are very low. Another possibility is that the ultrasound affects the Sertoli cells, or “nurse” cells, that are involved in sperm production.

Fertility experts cautioned that the long-term effects are not yet clear and that, even if shown to be safe, it would be several years before the technique could gain approval. Allan Pacey, a senior lecturer in andrology at the University of Sheffield, said: “There is certainly a place for an effective non-hormonal contraceptive in men, but whether men would find it acceptable to have their testicles scanned regularly remains to be seen.”

He added that it would be crucial to show that the technique was fully reversible and that the frequency and doses of ultrasound required did not result in any long-term damage to the sperm-producing cells, particularly at the genetic level.

Rebecca Findlay, of the Family Planning Association, said: “Men can be just as responsible and trustworthy as women when it comes to contraception. Women will need to do a massive mental sea change about contraception and evaluate their attitudes, possibly more than men will.”

A survey by the FPA on hormonal contraception last year found that one third of men said that they would definitely use a “male Pill” if one became available.