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Summer 2008 Sperm–Hyaluronic Acid Interaction: Assessment of Male Fertility and Selection of Mature Sperm for ICSI
Research conducted at the Yale Sperm Physiology Laboratory has led to a breakthrough in selecting mature sperm for use in in vitro fertilization treatment. The hyaluronic acid (HA) receptor of mature sperm, coupled with an HA–coated sperm selection Petri dish (PICSI® Dish, MidAtlantic Diagnostics, Mt. Laurel, NJ), allows direct observation of sperm–HA binding and ICSI selection of single mature sperm. HA–binding identifies sperm that would have been selected by the zona pellucida in natural and IVF fertilization. Conversely, sperm with arrested maturity do not bind to either hyaluronic acid or to the zona pellucida. Immature spermatozoa, present in every ejaculate (although in oligozoospermic men in higher proportion compared to normozoospermic men) are characterized by other attributes of arrested sperm maturity, in addition to the lack of HA binding, such as cytoplasmic retention, persistent histones, and DNA chain breaks. Further, the frequencies of sperm with chromosomal disomy and diploidy are reduced by four–to–five fold in HA–bound sperm versus the unselected sperm fraction of the same semen sample. This reduction is comparable to the increase of chromosomal aberrations in ICSI children. This is one of the great advantages of using HA–mediated ICSI sperm selection. Combined studies of sperm shape and chromosome probes have demonstrated that morphology does not distinguish haploid (normal) and aneuploid sperm. Thus, the best–looking sperm are not always mature or of high genetic integrity. HA–binding mediated sperm selection, a new inventive approach in ICSI sperm selection and in evaluation of male fertility, was developed at Yale in the Sperm Physiology Laboratory, Department of Obstetrics, Gynecology, & Reproductive Sciences. The scientific development and the work for validation have been directed by Gabor Huszar, MD, Senior Research Scientist, Director of the Laboratory and the Male Fertility Program.
The HA–sperm interaction method also provides an improved approach for semen analysis because, in addition to the conventional semen parameters of sperm concentration, motility and morphology, we can now assess the proportion of sperm that binds to solid–state HA (in a 15–minute slide test under the microscope) and that therefore would also bind to the zona pellucida during fertilization. HA–mediated ICSI sperm selection is expected to alleviate the genetic concerns related to ICSI, thus addressing a potential major public health concern. HA–mediated ICSI sperm selection and the sperm HA–binding male fertility test have been approved by the FDA in the USA and by the European regulatory authorities, and the technology is distributed and used all over the world. The HA–mediated male fertility test and HA–mediated ICSI sperm selection are routinely practiced at the IVF and Sperm Physiology Laboratories of the Yale Fertility Center. For further information, please call Dr. Gabor Huszar at the Sperm Physiology Laboratory (203–764–6484). |
