It’s possible that you’re referring to a recent breakthrough in the field of contraception. Researchers have developed a new type of contraceptive that can effectively block the movement of sperm, potentially offering a new way to prevent pregnancy. The contraceptive works by using a protein called N-ethylmaleimide-sensitive factor (NSF), which is found in human cells and helps to regulate the movement of other proteins.
When the NSF protein is introduced into the reproductive system, it can block the movement of sperm and prevent them from reaching the egg. While this is a promising development, it is still in the early stages of research and it may be some time before a contraceptive based on this technology becomes available.
Engineered antibodies immobilize sperm in animal studies, paving the way for women to use nonhormonal contraception. Scientists at the University of North Carolina at Chapel Hill are developing a new type of female contraception using the precision targeting of monoclonal antibodies.
Monoclonal antibodies are well-known for their ability to combat invading germs and are used to treat and prevent diseases ranging from cancer to COVID-19. Antibodies are now being considered for a new mission: immobilizing sperm before it can reach an egg.
Many women avoid hormonal contraception due to real and perceived side effects. These side effects can include spotting, nausea, depression, weight gain, and migraines. Furthermore, estrogen-based hormonal contraception can be harmful to some women. There is a significant unmet need for non-hormonal contraceptives for women.
Samuel Lai
Carolina researchers created ultra-potent antibodies that effectively trapped and blocked more than 99.9% of human sperm in animal testing. According to the promising study results published in Science Translational Medicine, antibody-based contraception may offer women a non-hormonal option to prevent pregnancy.
“Many women avoid hormonal contraception due to real and perceived side effects,” said Samuel Lai, professor at the UNC Eshelman School of Pharmacy’s Division of Pharmacoengineering and Molecular Pharmaceutics.
These side effects can include spotting, nausea, depression, weight gain, and migraines. Furthermore, estrogen-based hormonal contraception can be harmful to some women. “There is a significant unmet need for non-hormonal contraceptives for women,” said Lai.
Antibodies as line of defense
Nearly half of all pregnancies in the United States are unintended, and Lai is among scientists across the country who are advancing the idea of using anti-sperm antibodies for contraception.
“We were inspired by infertility that occurs in some women who develop antibodies against their partner’s sperm,” said study first author Bhawana Shrestha, a doctoral student in the Department of Microbiology and Immunology at the UNC School of Medicine and graduate research assistant at the school of pharmacy.
The antibody under investigation was isolated from an infertile woman and targets a specific surface antigen found on human sperm. When it is mixed with sperm, it quickly clumps together. “We engineered antibodies that were more than 10 to 16 times more potent at agglutinating sperm and reducing sperm permeation through mucus than the best-known antibody using our highly multivalent IgG platform,” she said.
The effect of antibodies was studied in sheep, which have reproductive tracts similar to human females. Both naturally occurring antibodies and the newly engineered antibodies effectively stopped all human sperm motility at a high dose of 333 micrograms of antibody, and at a low dose of 33.3 micrograms, the modified antibodies, but not the original antibodies, trapped 97% to 99% of sperm.
Next step: clinical trials
But monoclonal antibodies are known as expensive drugs, which puts their usefulness as an affordable contraceptive up in the air. However, researchers believe that by increasing the potency, much lower doses of the multivalent antibodies may be needed for effective contraception.
“We think these second-generation molecules will provide not only greater potency but will translate to lower costs that make the approach cost-effective,” said Lai. Mucommune, a startup spun out of the Lai Lab, has licensed the molecule for the development of an antibody-based contraceptive. The company will focus on safety and manufacturing to prepare for human clinical trials that could start in 2023.
The researchers are working on incorporating the antibodies into an intravaginal ring that gradually releases the antibodies or a dissolvable film that is placed in the vagina and spreads antibodies before sex.
“We believe that by avoiding exogenous hormones and developing a women-controlled contraceptive method, the antibodies developed here could meet the contraceptive needs of millions of women, help to reduce the number of unintended pregnancies, and alleviate the health care costs of unintended pregnancies, which some estimate to be in excess of $20 billion per 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 study team.
