The Impact of Biotechnology on Reproductive Medicine

Abstract

Reproductive Medicine has been at the forefront of the biotechnology revolution. Over the last three decades, a very significant proportion of abstracts at our major meetings and papers in our journals have employed molecular techniques to elucidate basic gene expression and cellular metabolic pathways in the study of reproductive processes. The resulting insights have yielded new understanding of the basic mechanisms of reproductive diseases and innovative therapeutic modalities. Specific examples will be used to illustrate this remarkable progress. In 1988, Hollands reported the rescue of lethally irradiated rats by infusion of haemopoietic stem cells from mouse blastocysts grown in vitro (1). This remarkable study was published decades before stem cells (now induced pluripotent cells from the recipient to avoid rejection) became a clinical tool for repopulating the bone marrows of cancer patients following lethal doses of chemotherapy and or radiation. In 1992, Lou Ignarro, who later shared a Nobel Prize for the discovery of nitric oxide (NO), showed using human penile tissue that the effect of neural NO release was enhanced by an inhibitor of cyclic GMP degradation (2), leading to the development of highly effective treatments for erectile dysfunction (ED) (3). Further elucidation of the factors influencing NO production and degradation has led to important insights into lifestyle and nutritional factors influencing erectile health (4, 5). In the mid-1990’s, as the result of work carried out by the research group under Antonio Pellicer in Valencia, Spain and others, the etiology of increased vascular permeability and consequent extreme fluid shifts characteristic of ovarian hyperstimulation syndrome (OHSS) were shown to be due to increased expression of vascular endothelial growth factor (VEGF) and VEGF receptor2 (VEGFR2) (6). The incidence of OHSS was reduced by 50% by identifying and clinically utilizing the role of dopamine agonists to inhibit phosphorylation of VEGFR-2. That discovery, together with understanding and thereby avoidance of clinical factors stimulating VEGF, has now made morbid and potentially fatal OHSS a rare occurrence. Again in the 1990’s David Gardner, along with others, defined the reproductive tract nutrients available during in vivo embryo development and the specific stagespecific requirements of embryos developing to the blastocyst stage. Those insights and clinical experience enabled the design of media specifically for embryos over the first 72 hours and the following 24 to 84 hours of culture (7), improving IVF efficiency and making accurate chromosome analysis a reality. Study of blastocyst metabolism that predicts a successful pregnancy has been progressing rapidly (8). In the late 1990’s techniques became available to assess DNA fragmentation of sperm, first by flow cytometry and later by techniques such as TUNEL and COMET. DNA fragmentation increases with age (9) and may contribute to the low success rates in women over age 40, although the effect of male age was observed to be less with younger female age (10). The effect on IVF outcome also appears to be less for women responding normally to ovarian stimulation compared to low responders (11). These observations have suggested that cytoplasm of the better quality oocyte may be able to correct DNA fragmentation. The observation that DNA fragmentation is correlated with semen oxidative stress (12) has validated successful treatment with antioxidants (13). Because DNA fragmentation increases during transit through the male collecting system, testicular extraction of sperm has been used successfully if frequent ejaculation and antioxidants are not sufficient (14). Decreased coital frequency with age, in part due to decreased erectile function, contributes to infertility in older couples (15). In the late 1990’s the importance of omega-3 fatty acids in the function of sperm membranes was being elucidated and correlated with indices of sperm quality and male infertility (16). Safarinejad reported a randomized trial showing highly significant benefits of omega-3 supplementation on sperm density, motility, and strict morphology (16). Semen concentrations of omega-3’s correlated with those improvements and also with semen endogenous antioxidants. Supplementation with omega-