In today’s world, women have various options for using long-term and reversible contraceptives, but a majority of the options for men are either single-use, namely condoms or hard to reverse, like vasectomies.
Taking a leap toward a long-lasting, safe and reversible male contraceptive, scientists have created magnetic and biodegradable nanomaterials that help reduce the chance of mice fathering pups for a minimum of 30 days.
Their study was published in the ACS’ Nano Letters journal.
High temperatures can be caused by wearing too-tight pants or underwear, resulting in the decrease of sperm count in men. A few scientists have examined the more intense heating of nanomaterials introduced into the testes as a form of male birth control.
Yet, the injection can be distressing, the heating can cause damage to the skin, and the majority of the nanomaterials tested until now are not biodegradable. Therefore, Weihua Ding, Fei Sun, and collaborators desired to design a safe and efficient magnetic-thermal method for male contraception that does not need to be directly injected into the testes.
Two forms of iron oxide nanoparticles were experimented with by the scientists, which are biodegradable and can be directed and heated using magnetic fields, as male contraceptives. The first type of nanoparticle was coated with polyethylene glycol (PEG) and the second one with citric acid.
The PEG-coated nanoparticles could be heated to elevated temperatures, but they were not as easily handled by magnets as the other ones. Therefore, the scientists injected recurrent doses of citric acid-coated nanoparticles into the bloodstream of mice for around two days, directed the nanomaterials to the testes with magnets, and further employed an alternating magnetic field to the area for 15 minutes.
The testes were heated by the nanoparticles to a temperature of around 104 °F, shrinking them and hindering spermatogenesis before gradual recovery 30 to 60 days following treatment. The mice could not father any pups for about a week after treatment, but they were back to fathering about 12 pups per pregnant female on the 60th day.
The scientists state that the nanoparticles did not cause any harm to the cells and were slowly removed from the body, thereby providing new prospects for male contraception.
The researchers acknowledge financial support from the National Key Research and Development Program of China, the Natural Science Research of Jiangsu Higher Education Institutions of China, and the Open Fund of Key Laboratory of Advanced Display and System Applications of Ministry of Education (Shanghai University).
Ding, W., et al. (2021) Magnetic Testis Targeting and Magnetic Hyperthermia for Noninvasive, Controllable Male Contraception via Intravenous Administration. Nano Letters. doi.org/10.1021/acs.nanolett.1c02181.