Researchers injected mice with magnetic, nanomaterials that halted sperm production for 30 days; providing a viable option for male birth control.
Over the decades, man has made considerable progress in science and technology. Unfortunately, the same cannot be said for male birth control. Current male contraceptive options include condoms and the often-irreversible vasectomy. Both of which men are hesitant to employ. On the other hand, women are ‘blessed’ with several options ranging from pills and IUDs to implants. Why the discrepancy? According to researchers, there is a lack of funding and interest in male contraceptives. Moreover, the complex male anatomy makes it harder to develop a viable option for men.
Now, researchers at Nantong University, China have developed magnetic particles that can serve as an effective male birth control option. The team relied on heat, a natural contraceptive. Raising the temperature of the scrotum, due to tight underwear or pants, can lower sperm counts in men. Therefore, the researchers looked for an artificial method of heating up the testes.
In the past, studies have reported on the use of nanomaterials for inducing hypothermia. Using lasers, the researchers would heat the metallic particles; the resultant heat would then sperm count. However, injections are painful and using of laser can damage the skin and cause pain. Moreover, most of the nanomaterials are toxic and non-biodegradable. Therefore, Ding et al. looked for non-toxic degradable nanoparticles that could be guided using magnetic fields.
A Possible Option for Men
The team tested two different forms of iron oxide nanoparticles: one coated with polyethylene glycol (PEG) and the other with citric acid. Although the one coated with citric acid caused smaller increases in temperature, it was easily guided with the help of a magnetic field. Therefore, researchers chose to stick with it for their study.
They injected male mice with several doses of the nanoparticles over a period of two doses. Then, using magnets they guided the nanoparticles to the testes. Once in the testes, they applied an alternating magnetic field to induce hyperthermia. This brought the temperature of the testes to 40 degrees centigrade. This ‘magnetic hyperthermia’ caused the testes to shrink and halt sperm production. This effect lasted for 30 to 60 days after treatment.
Following the treatment, the mice lost the ability to father any pups for seven days after the treatment. However, after two months, their fertility returned; they started fathering 12 pups per female. Thus, providing evidence of the method’s reversibility.
Notably, the team conducted their study in mice and there is no way of knowing how the results would translate in humans. However, it paves the way for the possibility of a safe and reversible male birth control method in the future.
Earlier, a Chinese herb called triptonide had also shown promise as an effective option for male contraceptives.
Weihua Ding, Zhichuan Chen, Yayun Gu, Zhengru Chen, Yanqiong Zheng, Fei Sun. Magnetic Testis Targeting and Magnetic Hyperthermia for Noninvasive, Controllable Male Contraception via Intravenous Administration. Nano Letters, 2021; 21 (14): 6289 DOI: 10.1021/acs.nanolett.1c02181