Evaluation of Different Cryopreservation Protocols of the Testis Using 8-Hydroxy 2-Deoxyguanosine as Marker of DNA Damage.

Abstract

Background:Chemotherapy and radiotherapy can destroy or severely reduce spermatogenesis and thereby jeopardize fertility in the long term. There is still no medical treatment that guarantees fertility preservation after chemo- and radiotherapy. Now with recent improvement of assisted reproductive technologies (ART) and possibility of using testicular spermatozoa or epididymal spermatozoa at in vitro fertilization (IVF) by intracytoplasmic sperm injection (ICSI), cryopreservation of testicular tissue is an option in fertility preservation for males who will lose spermatogenic cells as a result of chemo-and radiotherapy and for males with azoospermia.Objective:This study is an attempt to evaluate oxidative DNA damage in the mice testicular tissue after cryopreservation/thawing cycle when using different types of cryoprotectants as well as to investigate the changes that occur in mice testicular tissue after cryopreservation/thawing cycle as a model for human being.Methods:Fifty mature fertile male mice between 8- 12 weeks old were used in the current study. For each mouse, one testis was evaluated histologically and immunohistochemically (using 8-Hydroxy 2>-Deoxyguanosine as marker of oxidative DNA damage) without cryopreservation (control group). The other testis was evaluated histologically and immunohistochemically (using 8-Hydroxy 2>-Deoxyguanosine as marker of oxidative DNA damage) after six weeks of cryopreservation using different types of cryoprotectants (cryopreserved group).Results:The microscopically observation of slides obtained from cryopreserved testis differs according to the type of cryoprotectant (glycerol, 1,2 propanediol and dimethylsulfoxide), in the dimethylsulfoxide group, tissue sections showed no major differences versus control group, but in the histological sections obtained from tissue cryopreserved by glycerol as cryoprotectant showed moderate morphological and structural changes as compared with the control group. While, the tissue samples subjected to 1,2 propanediol as cryoprotectant displayed the severest morphological and structural changes as compared with the control group.Immunchistochemical results of the present study showed a highly significant (P<0.001) increase in oxidative DNA damage in the cryopreserved testis (46.78%, 63.45% and 32.59% represent cryoprotectant glycerol, 1, 2 propanediol and dimethylsulfoxide, respectively) compared with control group (19.27%) after six weeks of cryopreservation.Conclusion:From the results of the current study, it was concluded that there was alteration in testis histology after cryopreservation/thawing cycle and increase the level of oxidative DNA damage after cryopreservation/ thawing cycle. As well as dimethylsulfoxide cryoprotectant provide good protection for testis histology and DNA.