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The American Fertility Association’s Monthly Newsletter

April 28 , 2008

Protecting Fertility From The Evils of Plastic

It took a while, but both the U.S. and Canadian governments took action in April to issue warnings on the safety of Bisphenol A (BPA), the chemical used in the manufacture of hard plastic (polycarbonate) to make sports water bottles and baby bottles among thousands of other products. Canada’s version of the FDA is now calling BPA a dangerous chemical, and the National Toxicology Program of the National Institutes of Health declared it’s possible that the chemical is having a negative impact on human development and reproduction.

Reviewing the data from animal studies, the NTP, which determines if chemicals are in fact dangerous, now says it’s possible that exposure to low doses, similar to human exposure levels, produces a “variety of effects related to neural and behavior alterations, precancerous lesions in the prostate and mammary glands, altered prostate gland and urinary tract development, and early onset puberty in female (laboratory rodents) exposed during development...” ”

While noting that that the “lack of data on the effects of Bisphenol A in humans and despite the limitations in the evidence for ‘low’ dose effects in laboratory animals…the possibility that Bisphenol A may alter human development cannot be dismissed.””

Within days, Nalgene, the manufacturer of the ubiquitous hard plastic sports bottles, began recalling its BPA-laden products. REI, the large outdoor goods retailer joined in pulling polycarbonate bottles off the shelves.

Ferreting Out The Why Of What’s Bad About Synthetic Estrogens

Isolating exactly what is in synthetic estrogens, such as Bisphenol A so commonly found in everyday plastics, has such a deleterious effect on reproductive development has been a challenge. This month, Yale University Medical School researchers came up with a clearer understanding of how these chemicals affect a developing fetus, causing compromised fertility, as well as vaginal and breast cancers.

Exposing mice to DES, the infamous synthetic estrogen that has wreaked havoc on so many women born in the 1950s and 60s, the Yale team found changes in certain regions of the HOXA10 gene that continued beyond the time of development, persisting into adulthood. This indicated that exposure to DES and similar substances results in lasting genetic memory, known as "imprinting."

Quoted in published news reports, lead researcher Hugh S. Taylor, MD, professor in the Department of Obstetrics, Gynecology & Reproductive Science and section chief of Reproductive Endocrinology and Infertility, said “We found that HOXA 10 protein expression was shifted to the bottom portion of the uterus in the female offspring," said Taylor. "We also found increased amounts of the enzyme responsible for changes in the DNA. Rather than just changing how much of the protein is there, DES is actually changing the structure of the HOXA 10 gene.

"These findings bring us closer to understanding the way in which DES interacts with the developing reproductive system.”

Although DES is off the market, pregnant women are frequently exposed to other synthetic estrogens that may have an adverse impact on the reproductive tract of female fetuses, as well as on their fertility.

Oeufs A La Francais: Upping the Odds of Successful Pregnancy

A team of French researchers said it has identified the genetic markers that make it possible to select the ova with the best chance of a successful pregnancy in IVF treatment. Reporting their results in the journal Human Reproduction, the scientists lead by Marc-Andre Sirard of Université Laval found that the “good eggs” were surrounded by follicular cells in which five genes were expressed in abundance and which provided information about the egg quality.

After initial work with bovine follicular cells, the Laval group confirmed their findings in a human study based on 40 female volunteers undergoing IVF treatment.

The Implications for IVF treatment are profound. If this process of egg selection is as efficacious as the researchers report, it significantly boosts the likelihood of positive outcome of single embryo transfer, at the same time it reduces the risk of multiples—a phenomenon that has plagued IVF. Moreover, this manner of egg selection could diminish the need to breach the integrity of the embryo in order to choose the one with the best chance of developing into a pregnancy.

The research team is so confident of its study’s results, that it has filed for an international patent on the genomic tool.

Rats! Another Step In The Stem Cell March

Only a few months after the whirlwind of news reports and commentary surrounding the creation of stem cells from human skin cells, a new team reported that it successfully treated Parkinson’s Disease in rats using a similar technique that reprogrammed rat skin cells to become “embryonic-like” stem cells.

Although the findings, once again, sparked optimism that it will be possible to generate pluripotent stem cells—universal cells that can develop into any other kind of cell—without using embryos, scientists once again cautioned that the process is still in its earliest stages of development.

The most recent advance, the result of work by a team of scientists at the White Institute for Biomedical Research, involved treating adult rat skin cells with four genes, causing them to regress yielding something very much akin to an embryonic stem cell. These blank slate cells were turned into brain tissue and transplanted into rat brains affected with Parkinson’s. After eight weeks, the rat brains began to generate dopamine, critical to managing the symptoms of Parkinson’s.

A cautionary note: this particular technique raises the risk of spurring tumor growth.

Rudolf Jaenisch, a scientist at WIBR and the Massachusetts Institute of Technology who oversaw the study, told The Boston Globe, that the same process could be used to repeat the technique in humans but that "human work is a long way off."

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