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Abstract
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Induction of apoptosis involves a series of cellular, morphological and biochemical changes that lead to cell death. Cellular apoptosis occurs during sperm freezing due to high levels of free radicals. The central component of apoptotic formation consists of a family of cysteine proteases called caspases. Activation of caspase-3 during cascading reactions destroys proteins and nucleic acids, leading to cell lysis. This study aimed to evaluate the effect of xylitol as a cryoprotectant on human sperm apoptosis. In this study, semen samples were collected from 15 normal men. The samples were divided into three groups. The first group consisted of samples tested in the fresh state (fresh control). The second group consisted of samples frozen with xylitol-freezing medium (cryopreservation control) and the third group included samples frozen with xylitol-freezing medium (cryopreservation). After evaluating sperm parameters, including total and progressive motility, the process of apoptosis was assessed in all three groups. After cryopreservation, the percentage of total and progressive motility in the frozen treated group was significantly higher than in the frozen control group. Also, the mean percentage of apoptotic sperms in the frozen treated group was significantly lower than in the frozen control. Therefore, it can be concluded that the cryopreservation process eliminates membrane asymmetry and causes apoptosis. In the presence of xylitol, a decrease in the apoptotic process is observed during the cryopreservation, thereby increasing the number of functional sperm available for assisted reproductive techniques
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