Cryopreservation of human spermatozoa with pentoxifylline improves the post-thaw agonist-induced acrosome reaction rate

Cryopreservation causes extensive damage to spermatozoa, thereby impairing their fertilizing ability. The purpose of this study was to determine if th e direct addition of pentoxifylline to the seminal plasma before cryopreser vation improved sperm motility and acrosome reaction, Semen specimens from 15 healthy volunteers were divided into two aliquots, One aliquot was treat ed by adding 5 mM pentoxifylline directly to the seminal plasma (treatment group) and the other aliquot received no treatment (control group). Both al iquots were then cryopreserved by using the liquid nitrogen freezing method . The percentage of motile spermatozoa and various motion characteristics w ere then evaluated by performing computer-assisted semen analysis. The sper m viability was determined with a supra-vital dye, Hoechst-33258, and the a crosome reaction (spontaneous and calcium ionophore-induced) was monitored using fluorescein isothiocyanate-conjugated peanut Lectin (FITC-PNA) bindin g assays. Pentoxifylline treatment significantly increased the sperm motili ty, the amplitude of lateral head displacement, the hyperactivation status, and the frequency of spontaneous acrosome reactions before freezing (P < 0 .05), After post-thaw, no difference in motion characteristics (except perc entage motility) between treated and control groups were observed. Acrosome loss due to the freeze-thaw process was less in the pentoxifylline-treated group (P = 0.0003). In addition, the percentage of cryopreserved acrosome- intact spermatozoa that underwent further acrosome reactions in response to calcium-ionophore challenge was significantly higher in the treated group (P = 0.03), Pentoxifylline treatment before freezing improved the acrosome reaction to ionophore challenge in cryopreserved spermatozoa. Treatment wit h pentoxifylline appears to minimize sperm damage during the freeze-thaw pr ocess and may improve fertilization rates with assisted reproductive proced ures such as intrauterine insemination or in-vitro fertilization.