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Scientists are working on a contraception that will stop sperm from spreading


In an animal research, engineered antibodies trap sperm, opening the door for women to use nonhormonal contraception.

The precise targeting of monoclonal antibodies is being used by researchers at the University of North Carolina in Chapel Hill to develop a novel form of female contraception.

Monoclonal antibodies are used to treat and prevent anything from cancer to COVID-19 because of their capacity to fight against invading bacteria. Antibodies are now being considered for a new mission: immobilizing sperm before it reaches an egg.

Carolina researchers created ultra-potent antibodies that efficiently caught and inhibited more than 99.9% of human sperm in animal tests. According to the encouraging research findings published in Science Translational Medicine, antibody-based contraceptives may provide women a non-hormonal alternative for preventing pregnancy.

“Many women forgo hormonal contraception because of actual and perceived adverse effects,” said Samuel Lai, professor of the UNC Eshelman School of Pharmacy’s Division of Pharmacoengineering and Molecular Pharmaceutics.

Intermittent bleeding, nausea, depression, weight gain, and headaches are some of the side effects. Hormonal contraception based on estrogen may also be dangerous to certain women.

“There is a significant unmet demand for non-hormonal contraception for women,” Lai added.

Antibodies serve as a first line of defense.

Nearly half of all births in the United States are unwanted, and Lai is one of several experts throughout the nation who are pushing for anti-sperm antibodies to be used as contraception.

“Infertility that occurs in some women who develop antibodies against their partner’s sperm inspired us,” said study first author Bhawana Shrestha, a doctoral student in the UNC School of Medicine’s Department of Microbiology and Immunology and a graduate research assistant at the school of pharmacy.

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They’re investigating an antibody that targets a specific surface antigen found on human sperm and was obtained from an infertile lady. When it’s mixed with sperm, it instantly clumps them together.

“We created antibodies that were more than 10 to 16 times more effective in agglutinating sperm and reducing sperm penetration through mucus than the best-known antibody using our highly multivalent IgG platform,” she added.

Antibodies were studied in sheep, which have reproductive processes that are comparable to human females. Both naturally occurring antibodies and newly created antibodies efficiently halted all human sperm movement at a high dosage of 333 micrograms of antibody, while the modified antibodies, but not the original antibodies, captured 97 percent to 99 percent of sperm at a modest dose of 33.3 micrograms.

Clinical trials are the next stage.

However, monoclonal antibodies are known to be costly medications, therefore their utility as a low-cost contraception is debatable.

Researchers anticipate that by enhancing the effectiveness of the multivalent antibodies, substantially smaller dosages of the antibodies may be required for effective contraception.

“We believe that these second-generation compounds would not only deliver increased efficacy, but also decrease prices, making the method cost-effective,” Lai added.

The molecule has been licensed for development of an antibody-based contraception by Mucommune, a firm formed out of the Lai Lab. To prepare for human clinical trials, the business will concentrate on safety and production. These studies might begin in 2023.

The researchers are working on putting the antibodies into an intravaginal ring that distributes antibodies gradually, or a dissolvable film that is implanted in the vagina and spreads antibodies prior to intercourse.

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“We think the antibodies created here might address the contraceptive requirements of millions of women, assist to minimize the number of unplanned births, and relieve the health care expenses of unexpected pregnancies, which some estimate to be in excess of $20 billion a year,” Lai said.

Researchers from UNC-Chapel Hill, the University of Texas Medical Branch, Boston University School of Medicine, and Mucommune, LLC are part of the research team.

The research was supported by the National Institutes of Health, Eshelman Institute of Innovation, Packard Foundation for Science and Engineering, National Science Foundation, and PhRMA Foundation.

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