Sperm DNA fragmentation induced by cryopreservation: new insights and effect of a natural extract from Opuntia ficus-indica

Objective To analyze the effect of cryopreservation on sperm DNA fragmentation (SDF) in two cytometric sperm populations, PI brighter and PI dimmer , and to test the effects of Opuntia ficus-indica (OFI) extracts, which contain antioxidants and flavanoids, and of resveratrol on cryopreservation of human semen. Design In vitro prospective study. Setting Institutional study. Patient(s) Twenty-one normozoospermic men undergoing semen analysis for couple infertility. Intervention(s) Cryopreservation using the routine method in the presence of OFI extracts or resveratrol. Main Outcome Measure(s) Measurment of SDF by TUNEL/PI flow cytometric method to evaluate sperm motility (by automated motion analysis, CASA system) and viability (by eosin/nigrosin staining) in the two populations of sperm PI br and PI dim . Result(s) Cryopreservation induced an increase of SDF only in the PI br sperm population. The increase was negatively dependent on the basal values of SDF in the same population. Addition of OFI extracts and resveratrol to the cryopreservation medium slightly but statistically significantly reduced SDF in the PI br population without affecting the deleterious effect of cryopreservation on sperm motion parameters or viability. Conclusion(s) The increase of SDF in the PI br population, which is unrelated to semen quality, suggests that caution must be taken in using cryopreserved semen, as morphologically normal and motile sperm may be damaged. The addition of substances with multifunctional properties such as OFI extracts to cryopreservation medium is only slightly effective in preventing the dramatic effects on SDF.