Effect of carboplatin on the functional integrity of the human sperm membrane in vitro.

Although it is well known that carboplatin is a drug that binds directly to DNA, causing DNA-DNA and DNA-protein crosslinks, which is the presumptive method for killing cells, the whole mechanism of action of carboplatin on spermatozoa is unclear. There are no published data in peer-reviewed journals focused on the interaction between carboplatin and cell membranes. Therefore, the purpose of this study was to investigate the minimal concentration of carboplatin that would affect the functional integrity of the human sperm membrane in an in vitro model. Human-ejaculated spermatozoa were obtained from 20 healthy normozoospermic donors. Solutions (SOL) of 0.5 mL of the semen samples and 0.5 mL NaCI (0.9%) containing increasing concentrations (7.5, 15, 30, and 60 ng) of carboplatin per 1 mL of SOL were prepared. Then, the hypoosmotic-swelling (HOS) test and the eosin test were performed on these samples and compared with the control (no carboplatin) group. Significant damage to the plasma membrane in the head region (eosin test positive) and in the tail region of spermatozoa, as assessed by the HOS test, was observed in concentrations of 30 and 60 ng carboplatin per 1 mL of SOL in comparison to the values evaluated in the control group. The results demonstrate that a minimal carboplatin concentration of 30 ng/mL causes significant damage to membrane integrity of spermatozoa in healthy volunteers.