Incorporación del test de dispersión de la cromatina espermática al laboratorio andrológico

Abstract

ObjectiveTo develop the sperm chromatin dispersion test (SCD) for evaluating the DNA fragmentation in semen. Materials and methods57 normozoospermic (WHO 2010) patients were invited to participate in the study after signing the consents. DNA fragmentation was evaluated by SCD, objectively and subjectively, after oxidative stress with H2O2 and also in motile selected samples (swim up or density gradient), as well as in frozen and thawed samples. ResultsThe objective assessment showed that minor fragmentation is associated to a larger halo size by definition, but also a significant increase in the size of the nucleus is observed. Oxidizing treatment (>100μM of H2O2) increases the fragmentation index in a dose-depend way without affecting sperm viability and motility. Different techniques of motile sperm selection (swim up or density gradients) decrease the fragmentation index with an individual susceptibility. Regardless of the sample (semen, suspension or post swim up direct freezing to –20°C allows to delay the test. ConclusionSubjective evaluation of the SCD test is sufficient for the clinical laboratory, evaluating the relation halo/nucleoid for the classification. To set up the SCD a dose-response curve with oxidizing treatment is required as a positive control of damage. The use of sperm selection methods used in assisted reproduction, decreases the fragmentation index, however individual susceptibility was observed. The SCD could be delayed by freezing the sample which allows saving of reagents and processing time.