P-997: Clinical use of pentoxifylline for freeze-thawed spermatozoa not improve embryo quality

Abstract

Pentoxifylline (PTX) is a metilxantina, clinically used as an artificial sperm stimulant to enhance sperm motility in many in vitro fertilization (IVF) programs. By inhibiting phosphodiesterase, pentoxifylline increases the intracellular cAMP level, and thus contributes to sperm capacitation, hyperactivation, and acrosome reaction. With the introduction of ICSI, its evident the ability to achieve high fertilization and pregnancy rates regardless semen parameters. Moreover, the use of cryopreserved sperm was then developed with success, and sperm motility after freeze-thawed procedure is one of the main determinants of the successes of ICSI. This study was designed to evaluate the effect of PTX applied to freeze-thawed spermatozoa, on fertilization rates and embryo development after intracytoplasmic sperm injection (ICSI) cycles. Prospective experimental study. This pilot study included 15 couples who underwent assisted reproduction techniques (ART) by ICSI using frozen-thawed spermatozoa. After thawed, the sperm samples were processed by swim-up, and divided into two equal aliquots. The first was treated with 5mM PTX solution (PTX group) for 30 minutes at 37°C, and other without PTX (control - CT group), followed by sperm-wash and motility evaluation. The sperm samples were addressed to IVF laboratory for ICSI, and 117 oocytes in metaphase II (MII) were injected, 58 with spermatozoa of CT group, and 59 with PTX treated sperm. The fertilization rate, pro-nuclei morphology, early cleavage and embryo morphology on day +3 (transfer day) were evaluated. Mann-Whitney and qui-square testes were used as appropriate, p < 0.05 were considered statistically significant. Our results showed that spermatozoa treated with PTX presented total motility similar to CT group (30.1% ± 16.4 versus 34.9% ± 16.8, respectively; p = 0.534), as soon as the progressive motility (19.1% ± 14.2 versus 24.1% ± 15.7, respectively; p = 0.383). After ICSI, the normal fertilization rates, were 78.4% in the PTX group and 78.9% in CT (p = 0,456), and resulted in 82 embryos in which morphology parameters were evaluated. The percentage of embryos presenting good pro-nuclei morphology (PTX: 22.5% versus CT: 18.4 %; p = 0.655), as well as early cleavage (PTX: 32.1% versus CT: 28.6%; p = 0.838) were similar. Also, 58.1% of embryos on PTX group and 80.7% on CT, presented good morphology on day +3 (p = 0.097). A cumulative embryo score, according to morphological embryo parameters since fertilization day until transfer day were determined, and on the PTX group 58.6% of the embryos were considered good, while 82.8% in CT were in this class (p = 0.082). Embryos originated from ICSI using spermatozoa from both PTX and CT groups were transferred, and a total of 5 pregnancies were achieved (pregnancy rate: 36%). Although those are preliminary results, it was observed that the treatment of spermatozoa with PTX, in comparison with nontreated group, had similar results neither to improve the total and progressive sperm motility, nor to the other embryo parameters evaluated. It is known that the pentoxifylline is embryo toxic; indeed we found that although the sperm characteristics were similar, the embryo quality seems to be worse when the pentoxifylline was applied, suggesting that this protocol is not efficient. We propose that other protocols can be used in order to improve the motility of thawed spermatozoa and the embryo quality.