Role Of Sperm Chromatin Structure Examination In The Diagnosis And Treatment Of Male Infertility

Aim Sperm chromatin is the carrier of paternal genetic information.Integrity of sperm chromatin structure is necessary to normal fertilization,embryo development and pregnancy.The aim of this present study was to evaluate the role of sperm chromatin structure examination in diagnosis and treatment of male infertility by clarifying the relationship between human sperm chromatin structure status and traditional semen parameters,male infertility and outcome of IVF-ET,and the influence of freeze-thawing on human sperm chromatin structure.Materials and methods The study was conducted in three parts.First,semen samples from 36 infertile men and 18 healthy donors were collected.Sperm DNA fragmentation was determined by TUNEL and sperm chromatin packaging was determined by CMA3 staining.Difference of the two chromatin parameters between infertile men and healthy men was determined.And the correlation between sperm chromatin structure parameters and traditional sperm parameters was assessed.Secondly,136 couples undergoing IVF-ET were involved while non-spermatozoon factors were limited to minimum.The remained sperm samples were collected after in vitro fertilization.Sperm DNA fragmentation was determined by sperm chromatin dispersion test and sperm chromatin packaging by CMA3 staining.Correlation between sperm chromatin structure parameters and fertilization rate and good embryo rate were evaluated.Sperm chromatin structure parameters of patients who achieved pregnancy were compared with those of the patients who failed to achieve a pregnancy.Third,semen samples of 22 donors of sperm bank were collected.Sperm DNA integrity was determined by TUENL before and after freezing.Difference between sperm DNA integrity and traditional parameters before and after freeze-thawing,and correlation between sperm cryo-damage and parameters before freezing were assessed.Results TUNEL positivity and CMA3 positivity of infertile men were both significantly higher than those of the controls.The two sperm chromatin parameters were both significantly correlated to traditional semen parameters.In the couples undergoing IVF-ET,sperm SCD positivity and CMA3 posititivity were found significantly and negatively to be correlated to fertilization rate after IVF;however,neither of the two chromatin parameters had direct effect on early embryo development.In couples who achieved a clinical pregnancy,sperm SCD positivity and CMA3 positivity were both lower than those who failed to pregnancy.Sperm DNA fragmentation was significantly increased,while sperm density and motility were significantly decreased after freeze-thawing.No significant correlation was found between sperm DNA integrity cryo-damage and sperm parameters before freezing.Conclusions Sperm chromatin structure defect is more severe in infertile men than in healthy men.Sperm chromatin structure anomaly is one of the reasons of male infertility. Defects in sperm chromatin structure may be of negative effects on fertilization rate and pregnancy after IVF-ET,leading to failure of assisted reproductive treatment. Freeze-thawing can damage sperm DNA;however,sperm DNA fragmentation rate of health donors after freeze-thawing remains to be relatively low and would not affect the outcome of assisted reproductive treatment.There is a correlation between sperm chromatin parameters and traditional semen parameters;however,the correlation coefficient is low and sperm chromatin status can not be predicted through traditional parameters.Sperm chromatin structure examination can provide useful information in diagnosis,treatment and prognosis of male infertility,especially for the unexplained infertile men and couples undergoing IVF-ET.