PLATELET-ACTIVATING-FACTOR AND PENTOXIFYLLINE AS HUMAN SPERM CRYOPROTECTANTS

Objective: To explore whether the addition of platelet-activating fact or (PAF) or pentoxifylline before cryopreservation improves the recove ry of motile viable sperm and what role cyclic adenosine monophosphate (cAMP) plays in this recovery. Design: Washed sperm was cryopreserved in the absence of and in the presence of PAF and pentoxifylline. Afte r 2 weeks these samples were quick-thawed and evaluated before and aft er washing for sperm motility and other motion characteristics. Sperm viability and cAMP concentration were determined to compare the effect s of these cryoprotectants. Results: When sperm samples were cryoprese rved in the presence of PAF or pentoxifylline, an improvement in the r ecovery of motile sperm in unwashed and washed post-thaw samples was o bserved. There were 38% more motile sperm recovered with PAF and 15% m ore with pentoxifylline when compared with untreated samples. In compa rison with the unwashed samples, sperm motility in post-thaw samples w as lowered by the washing procedure. When PAF was used as a cryoprotec tant, a significant improvement in the linearity and straight line vel ocity of the post-thaw sperm was observed. When pentoxifylline was use d as a cryoprotectant, lateral head displacement was significantly imp roved in the post-thaw samples than in the control group. Both PAF- an d pentoxifylline-treated samples contained a greater number of viable sperm than the control. The cAMP concentrations in post-thaw samples w ere 12-fold higher in pentoxifylline-treated samples and 4-fold higher in PAF-treated samples when compared with the untreated control. A 4- fold decrease in cAMP concentration was observed in post-thaw control samples compared with fresh-washed sperm. Conclusions: The results of this study suggest that both PAF and pentoxifylline are useful cryopro tectants for the increased recovery of motile, viable sperm. Although increased recovery of motile sperm in pentoxifylline-treated samples i s related to higher cAMP levels, the cryoprotective effect of PAF does not appear to be due to increased cAMP.