Effects Of Vitrification And Standard Slow Freezing Method On Motility And DNA Integrity Of Small Numbers Of Human Spermatozoas

BackgroundThe treatments, such as ICSI (intracytoplasmic sperm injection) and new advancesin minimally invasive sperm recovery from the testis/epididymis, provide a neworientation in the treatment of azoospermic men, who previously had no chance ofhaving a biologic child. Surgical retrieved spermatozoa are often poor in-situ motile andonly present in small numbers, the azoospermic men is necessitating repeat surgicalinterventions if pregnancy is not achieved.Efficient cryopreservation of surgicallyretrieved spermatozoa can reduce the surgical intervention’s number and thus avoids thecomplications associated with repeated surgeries， such as inflammation orhematoma at the biopsy site even major complications such as testiculardevascularization and fibrosis. Using cryopreserved sperm also solve the logisticalissues associated with coordinating the women’s oocyte retrieval and eliminate the riskof no sperm being found on the day of oocyte retrieval. Given the specialcharacteristics of epididymal and testicular spermatozoa, conventional “slow” methodsof sperm cryopreservation may not be ideal.Many studies have been devoted to thedevelopment of the most suitable freezing techniques for small numbers of humanspermatozoa.Whatever the method used, to obtain good results it is essential to correctlyperform all the steps in sperm cryopreservation: the choice of more suitable carriers，thechoice of more suitable cryoprotectants and the suitable thawing procedure are particularly important.The current evidence is not sufficient to prove that one method isbetter than other methods.ObjectiveTo Compare the efficiency of vitrification and standard slow freezing methodon motility and DNA integrity of small numbers of human spermatozoaMethodsSeventy semen samples were washed by routine swim-up, each sample weredivided into two parts for vitrification and standard slow freezing. Motility andDNA fragmentation index(DFI) of the fresh spermatozoa, and thawed spermatozoaafter vitrification and standard slow freezing were detected respectively.ResultsThe motility and DFI of the fresh spermatozoa were (93.24±2.26)％and(6.70±5.78)％. The post-thaw motility and DFI of standard slow freezing methodgroup were (63.99±5.88)％and (9.58±6.89)％％；The post-thaw motility and DFI ofvitrification group were (63.07±6.69)％and (9.26±7.00). The motility in twocryopreservation methods were significantly lower than those before cryopreservation(P＜0.05).There was no significant difference in motility between two cryopreservationmethods (P＞0.05)．The DFI in two cryopreservation methods were significantlyhigher than those before cryopreservation (P＜0.05). There was no significantdifference in DFI between two cryopreservation methods (P＞0.05).ConclusionVitrification and standard slow freezing method all lead to spermatozoamotility decline and DNA damage, but there was no significant difference between two cryopreservation methods.