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

Cryopreservation causes extensive damage to spermatozoa, thereby impairingtheir fertilizing ability. The purpose of this study was to determine ifthe direct addition of pentoxifylline to the seminal plasma beforecryopreservation improved sperm motility and acrosome reaction. Semenspecimens from 15 healthy volunteers were divided into two aliquots. Onealiquot was treated by adding 5 mM pentoxifylline directly to the seminalplasma (treatment group) and the other aliquot received no treatment(control group). Both aliquots were then cryopreserved by using the liquidnitrogen freezing method. The percentage of motile spermatozoa and variousmotion characteristics were then evaluated by performing computer-assistedsemen analysis. The sperm viability was determined with a supra-vital dye,Hoechst-33258, and the acrosome reaction (spontaneous and calciumionophore-induced) was monitored using fluoresceinisothiocyanate-conjugated peanut lectin (FITC-PNA) binding assays.Pentoxifylline treatment significantly increased the sperm motility, theamplitude of lateral head displacement, the hyperactivation status, and thefrequency of spontaneous acrosome reactions before freezing (P < 0.05).After post- thaw, no difference in motion characteristics (exceptpercentage motility) between treated and control groups were observed.Acrosome loss due to the freeze-thaw process was less in thepentoxifylline- treated group (P = 0.0003). In addition, the percentage ofcryopreserved acrosome-intact spermatozoa that underwent further acrosomereactions in response to calcium-ionophore challenge was significantlyhigher in the treated group (P = 0.03). Pentoxifylline treatment beforefreezing improved the acrosome reaction to ionophore challenge incryopreserved spermatozoa. Treatment with pentoxifylline appears tominimize sperm damage during the freeze-thaw process and may improvefertilization rates with assisted reproductive procedures such asintrauterine insemination or in-vitro fertilization.