Impact of Caspase Activation in Human Spermatozoa

KEY WORDS caspase assays; sperm cryopreservation; sperm maturation; sperm separation ABSTRACT Caspases are central components in the apoptosis signaling cascade. The family of cysteine proteases transduces and enhances the apoptosis signal, and activation of effector cas-pases results in controlled cellular degradation. Although initially the presence of caspases in sper-matozoa was controversially discussed in recent years, many studies demonstrated their activation in male germ cells. Activated apoptosis signaling results in decreased fertilizing capacity of the sperm. This review presents the current knowledge on the role of caspases in human sperm. Tech-niques of caspase monitoring are highlighted. With regard to the high impact of caspases on the sperm fertilizing potential, physiological and pathological settings of caspase activation and inacti-vation are discussed. Finally, the effects of depletion of caspase-positive sperm are shown with vari-ous standard and molecular sperm preparation methods. Microsc. Res. Tech. 00:000–000, 2009. VC 2009 Wiley-Liss, Inc