MOLECULAR MECHANISM AND DEVELOPMENT CONSEQUENCES OF ICSI

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The practice of Assisted Reproductive Technology (ART) to overcome infertility in humans has increased dramatically during the past two decades and has culminated in the widespread use of intracytoplasmic sperm injection (ICSI), which can overcome instances of infertility previously thought to be intractable. Due to the inherent difficulty of conducting basic research with the limited amounts of human material and governmental bans on basic research of human eggs and pre-implantation embryos, the development of ART hs occurred essentially in the absence of basic research using an animal model system. In essence, this is an example of ART before science. In this grant application, we propose to use the mouse as a model system to study the molecular mechanism and developmental/behavioral consequences of ICSI. The ability of eggs to be activated by parthenogenetic stimuli increases with the time post-hCG administration and correlates with progression of metaphase II-arrested eggs into an interphase-like state. The first Specific Aim will test the hypothesis that, similar to parthenogenetic egg activation, the success of ICSI-induced egg activation increases with time following hCG administration. While ICSI has clearly revolutionized the treatment of male infertility, the molecular basis of how ICSI activates the egg and initiates the program of early development is poorly understood, especially in light of the fact that ICSI bypasses the normal pathway used by the sperm to fertilize the egg. Understanding the molecular basis of egg activation by ICSI will inevitably yield an understanding as to causes for its failure and rationale approaches to enhances its efficacy. The second Specific Aim will test the hypothesis that ICSI recruits signaling pathways that are normally activated during the course of natural fertilization and results in the normal complement of events of egg activation. The rapidly gaining use of ICSI as the method-of-choice to overcome human male infertility has raised a vigorous debate concerning the long-term risk imposed to the resultant offspring. Although it is reassuring at first glance that there is no apparent significant increase in the incidence of gross congenital abnormalities in ICSI-derived offspring, these children are still young and hence more subtle effects that influence behavioral and intellectual development may not yet be apparent. The third Specific Aim will test the hypothesis that mouse ICSI results in subtle developmental and behavior abnormalities in the generated offspring.