DIAMONDS in the Rough

Diamond-coated petri dishes protect sperm, thus improving IVF success rates. In vitro fertilization (IVF) already carries a hefty price tag—and the procedure may get costlier. A new method using nanocrystalline diamonds to carpet the bottom of petri dishes might ensure better survival and performance of sperm, improving IVF success, suggests a recent study in the Online Proceedings Library of the Materials Research Society.

“Our finding is likely to change the world of the petri dish,” explains Andrei Sommer, PhD, a materials scientist at Ulm University in Germany and the study’s lead author.

The average IVF cycle in the United States costs $12,400, according to the American Society of Reproductive Medicine. Because its success rate remains rather low, at about 30%, couples often undergo multiple treatment rounds before they successfully conceive. “Poor sperm performance” is a common problem, which typically requires actual injection of sperm into an egg. Yet for decades a part of the solution was right in front of the reproductive endocrinologists’ eyes: the petri dish.

The majority of IVF clinics—about 99.9%—use disposable petri dishes made from polystyrene plastic. When cell medium is applied to these dishes, the surface softens, as verified by a material harness-measuring device called a nanoindenter. The liquefied surface facilitates the formation of reactive oxygen species (ROS) that is toxic to cells, including sperm, oocytes, and embryos.

Searching for ways to get around this problem, Sommer remembered the title of an American Chemical Society press release on his previous work titled, “Diamonds may have been life’s best friend on primordial Earth,” which suggested that the surface of natural diamonds might have provided the right conditions for life-creating chemical reactions. For his research, the title served as a “guiding light sentence” and stimulated the inclusion of nanodiamond-coated petri dishes.

Sommer’s team applied fresh sperm samples, at about 4.1 million/mL — lower than the typical male sperm concentration of 20–200 million/mL — onto four diff erent types of petri dishes: polystyrene, quartz glass, sandblasted quartz glass coated with nanodiamonds, and quartz glass coated with nanodiamonds. After 42 hours at 37 degrees Celsius, about 20% more sperm survived in the pricey petri dishes, specifically the nanodiamond-coated plain and sandblasted quartz dishes, than the bargain polystyrene ones; the plain quartz containers without the diamond dusting yielded about 10% better viability than the polystyrene dishes.

The 42-hour time point could be important because, in IVF, after about 40 hours, the eggs are examined to see if they have become fertilized by the sperm and are forming embryos. The embryos are then placed in the woman’s uterus, thus bypassing the fallopian tubes, and hopefully ensuring pregnancy.

“During conventional IVF, sperm cells and oocytes both contact the bottom of the petri dish before the zygote is formed. These hours, and subsequent days prior to the transfer of the embryo into the recipient, are critical,” said Sommer, who added that sperm, while sensitive to ROS, are more robust to them than oocytes and embryos. Bradley Anawalt, MD, chief of medicine at the University of Washington Medical Center and specialist in male reproductive physiology, who was not involved in the study, described the work as “a relatively simple and straightforward study that asks a simple question no one has asked before.”

He added that this research backs up prior findings that infertile men are exposed to ROS in their testicles and includes speculation that antioxidant therapies might help these men. Given that banked sperm are often frozen in polystyrene containers, Anawalt posits that it is possible these containers could also affect the long-term viability of these frozen sperm.

Richard Rawlins, PhD, IVF laboratory director at RushCopley Center for Reproductive Health in Aurora, IL., mentioned that ROS scavengers are typically added to culture media to soak up any ROS in the dishes, yet perhaps these chemicals are not enough. He also called the study “a novel application of engineering helping out biology.”

Sommer’s group plans on testing the plates to see if it has any effect on sperm morphology and motility. They also want to ensure that the diamond coatings are biologically and chemically inert and do not release other toxic chemicals of their own.

The diamond-coated petri dishes are not only sperm and egg’s best friend. They could also aid in culturing stem cells and cancer cells, suggested Sommer, whose lab previously reported greater growth success of P19 mouse embryonic carcinoma cells on the diamond-dusted quartz petri dishes’ substrates.

Although these dishes could theoretically be reused through sterilization techniques such as autoclaving, Sommer correctly points out that “neither the IVF community nor the patients will accept making babies in ‘used’ petri dishes.”

If Sommer’s future research continues to indicate that these plates show promise, companies could start manufacturing these dishes in the next couple of years. And IVF clinics that purchase these dishes would somehow transfer the costs to the patients.

—Ruttimann Oberst, PhD, is a freelance writer in Bethesda, MD and a regular contributor to Endocrine News

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