Effect of Trolox on sperm quality in normozospermia and oligozospermia during cryopreservation

This study evaluated the effects of different concentrations of Trolox supplementation to cryoprotective agent (CPA) on post-thaw apoptosis-like events that include translocation of phosphatidyl serine (PS) to the cell surface, alterations in mitochondrial membrane potential (MMP), and DNA integrity of normozoospermic and oligoozoospermic semen samples. Spermatozoa from 20 normozoospermic men and 20 patients with oligoozoospermia were cryopreserved with cryo-protective agent containing 0, 20, 40, and 80 μM Trolox. Pre-cryopreservation and post-thaw sperm MMP, PS externalization and DNA fragmentation were evaluated by flow cytometry. Sperm frozen in extender with Trolox had greater MMP, lower DNA fragmentation and externalization of PS in both groups, though the most effective dose of Trolox in normozoospermic and oligoozoospermic semen samples were different. These findings support the use of Trolox as freezing extender supplement to improve the quality of cryopreserved human sperm, measured in terms of early apoptosis changes and DNA integrity, in both normozoospermic and oligoozoospermic men.