Effect of chromatin condensation on frozen-thawed sperm DNA integrity in normozoospermic men

Background and Aim: Sperm cryopreservation is a common technique used for management of male infertility. But this method has detrimental effects on sperm DNA and chromatin quality. Evaluation of different markers associated with the health of genetic material of sperm is beneficial for determination of the fertility of sperm. The aim of this study was to assess the effect of sperm chromatin condensation on frozen-thawed sperm DNA integrity in normozoospermic men. Material and Methods: In this experimental study, 30 semen samples from normozospermia men were cryopreserved for two weeks with a common technique used in most infertility centers, at -196 ° C and then thawed. Samples before and after freezing were evaluated for abnormal chromatin condensation, DNA denaturation and DNA fragmentation by toluidine blue (TB) staining, acridine orange (AO) staining and sperm chromatin dispersion (SCD) test respectively. Results: Before freezing, we found a significant correlation only between abnormal chromatin condensation (evaluated by TB) and DNA denaturation (assessed by AO) (p < 0.05). While after cryopreservation correlation was found between abnormal chromatin condensation and DNA denaturation and fragmentation (p < 0.05). Conclusion: Abnormal chromatin condensation can make DNA susceptible to denaturation and fragmentation.