I-9: Activation and Selection of Sperm for IVF and ICSI

Background: During spermatogenesis the sperm nucleus exchange histones against cystein rich protamines, which stabilize the sperm chromatin and protects the DNA against damages. At ejaculation the age of the patient, handling routines, processing of the semen sample and the storage of the final sperm suspension might damage the DNA. Sperm chromatin stability and DNA damages are evaluated with different methods are time-consuming, requires expensive equipment’s and does not take into account the individual intra-variability in semen quality. Conventional ICSI has therefore been shown to transfer paternally derived defects to the children. Furthermore, the selection of a healthy sperm for ICSI, via IMSI (Intracytoplasmic Morphologically-selected Sperm Injection), is very timeconsuming and requires additional equipment. However, the sperm’s ability to bind to the zona pellucida can easily be evaluated via the hyaluronan- binding assay (HBA), and if the HBA score is above 70% normal IVF can be used in border-line male factor prepared sperm suspensions. The denudation of oocytes with non-toxic ICSICumulase does not interfere with the sperms binding and fertilization ability, thus denuded oocytes could potentially be fertilized high HBA scored sperm. Thus we could reduce the use of ICSI and subjective selection of sperm for ICSI. Since human sperm also have receptors for a growth factor involved in the metabolism and motility of sperm it might be suitable for activation of sperm motility of immotile sperm from the testis? I will give an overview of the effects of GMCSF on the male reproductive tract, how it affects the performance of sperm and how it can be used for physiological selection of motile testicular sperm for ICSI. Denudation of oocytes with a highly purified, non-toxic, pathogen-free and recombinant human hyaluronidase solution (ICSICumulase) does not interfere with the sperm binding receptors on the zona pellucida. Thus if the sperm express zona pellucida binding sites on their plasma membranes they bind to and fertilize the oocyte. Spermatozoa that express such receptors are more mature, better morphology, higher chromatin stability, lower frequency of aneuploidy to receptors on the zona pellucida. A high zona binding competency correlates to the pregnancy rate, thus border-line sperm suspensions with a high HBA score can be used for insemination of ICSICumulase denuded oocytes. The sperm have direct access to the zona pellucida facilitating the fertilization step and there seems to be no differences between the fertilization rate between cumulus-intact or denuded oocytes. Sperm express receptors for GMCSF on their heads and mid-pieces and when exposed to this growth factor they become highly hyperactive. Even immotile testicular sperm become highly motile facilitating the selection of progressive sperm for micro-injection. These embryos have a higher implantation rate leading to high ongoing pregnancy rates. Conclusion: 1. Denudation of sensitive oocytes with non-toxic, recombinant human hyaluronidase is a more physiological, resulting in better embryo quality and higher pregnancy rates. 2. The denudation does not interfere with the sperm’s ability to bind and fertilize oocytes. Borderline sperm suspension, with proven oocyte binding ability, can therefore be used for IVF, thus the natural selection of sperm reduces the subjective selection of sperm occurring at ICSI. 3. GMCSF is a natural growth factors found abundant in both the female and male reproductive tract. The sperm has receptors for GMCSF in the head and the midpiece. GMCSF initiates hyperactivation of sperm from both normozoospermic and male factor patients. In immotile testicular sperm GMCSF initiates motility, which facilitates and shortens the time for selection of sperm for ICSI. If such sperm are used for ICSI it increases both the fertilization and clinical pregnancy rates.