Science Is Testing A New Way To Deliver Cancer Drugs To Patients — With, Uh, Sperm

We all learned about sperm in school: they swim, they find the egg, they fertilize, and babies ensue. But a new study published in the journal ACS Nano is revealing that there's more to the story — and that sperm, those mighty travelers in the vaginal canal, might be the key to delivering cancer-fighting drugs to the human body quickly, easily, and with minimum side effects. And it gets weirder: To achieve this goal, scientists have fitted sperm with little magnetic "vests" to help them steer. Hey, nobody can ever say science is boring.

Discovering how to deliver medications in the most effective way possible is a big deal. For centuries, humans have had to deal with some extremely crude methods, from poultices laid on the skin to inserts into every orifice possible; the hypodermic needle, which pierces the skin to give injections, wasn't invented until the 19th century. Getting drugs to the right part of the body in the right amount has been a central concern of doctors for a long time, and in recent years researchers have been turning to microscopic methods, from bacteria to genetically engineered "cell soldiers," to try to solve the problem. But sperm is a new option, and it may turn out to be a particularly excellent choice for combatting gynecological diseases in particular.

Sperm In Vests Are Coming For Cancer

The new research on sperm in vests comes from scientists at the Leibniz Institute in Dresden, and has emerged as part of a new age of discovery about sperm. This sperm-Renaissance has included revelations about how they navigate through the human body; at one point, scientists believed that sperm seemed to "smell" their way to the egg, but we now know that sperm have no olfactory sense and find their way to eggs using a series of chemical "signposts." We now also know the amazing mathematics behind sperm swimming patterns, and scientists in 2017 made the world's first 3D image of the moment when a sperm begins to fertilize an egg. But the revelation from the Leibniz scientists that sperm could be the new drug delivery mechanism for the 21st century may outstrip them all.

The scientists behind the sperm innovation created what they call a "sperm-hybrid micromotor." They fastened a magnetic harness onto the sperm (which was a cow sperm, not a human one) for navigation purposes — because the scientists weren't asking the sperm to find an egg. Instead, they were directing it towards a cancerous tumor.

The sperm in harnesses were "loaded" with the anticancer drug doxorubicin hydrochloride, a chemotherapy medication used for many different kinds of cancer. They were then guided towards the cancer tumor using a magnetic field, and once it reached its destination — the tumor wall — the harness released, allowing the sperm to do what it does best: swim. The sperm dove straight through the membrane of the tumor to deliver the drug itself.

The results were seriously promising. The researchers wrote in ACS Nano that the sperm seemed able to carry quite a lot of the medication without leaking it anywhere en route, which is helpful, because chemotherapy drugs can cause pretty horrible side effects and doctors work hard to minimize their exposure to healthy parts of the body. They noted that, when released in their thousands, the harnessed sperm were able to kill up to 80 percent of the tumor. That's a major breakthrough, and it matters a lot — particularly to women.

Why Sperm Might Be A Secret Weapon For Gynecological Illnesses

The tumor being targeted by the harnessed sperm was a lab-grown cervical cancer tumor. Cervical cancer is a serious issue; the American Cancer Society estimated that nearly 13,000 new cases would be diagnosed in 2017 alone. Detection is much more effective these days because of the invention of the pap smear, which helps women with abnormal cervical cells reach a rapid diagnosis early. But a study in 2017 found that the risk of dying of cervical cancer is 47 percent higher for white women and 77 percent higher for Black women than previous estimates had thought. The need to find better ways of treating and curing it is pretty pressing. The good news? Sperm seem to be pretty helpful.

There are other aspects to the success of the harnessed sperm, too. Other miniature options used for the delivery of drugs, including human-made microbes, have experienced issues in tests because the body's immune system has regarded them as threats and fought them off before they could reach their target. Sperm in the female reproductive system might not set off any alarm bells because, well, that's where they're expected to be. And they've got many other advantages. They don't breed when left on their own, are excellent swimmers, can be easily and cheaply harvested from volunteers, and are capable of being steered; in other words, they may be one of the best delivery systems nature has ever made.

"This sperm-hybrid micromotor is a biocompatible platform with potential application in gynecological healthcare, treating or detecting cancer or other diseases in the female reproductive system," the Leibniz scientists wrote in ACS Nano. But before you start imagining a future of sperm-armies charging up the reproductive tract to defeat cancers of all kinds, remember that this hasn't been tested with human sperm in an actual human body yet. Still, it's an exciting prospect: one day, we might be arming sperm with biological weaponry and sending it into the breach against women's health conditions of all kinds.