Upstream; a novel method for separating human motile sperms

Sperm preparation is a fundamental step in ART and attempt for developing new methods to be continued.

To evaluate the efficacy of upstream method for separation of human spermatozoa and its effects on sperm parameters including: motility, morphology, and concentration.

Semen samples from 17 men who referred to infertility clinic for evaluating their infertility problems were collected. Semen was placed in floor of the upper container of device, and then media was gently placed on the upper semen portion. During the procedure, semen flowed from upper container and dropped in lower container. When semen flowed, the non-motile sperms, cells, debris and seminal plasma enter the lower container, while only motile sperms separated by swimming upstream and go to the upper part of the medium. Finally, all of the semen flowed from the upper container to the lower one, and merely the medium remained, which contained motile normal sperms.

With application of upstream method, the recovered spermatozoa showed significant improvement with motility and normal morphology. The data showed that mean sperm motility increased from 39% to 90% (p<0.0001) and normal morphology increased from 25% to 32 % (p<0.0001) after processing using new method. In addition, the concentration of round cells decreased to zero in all samples.

The results indicate that upstream method can enrich the sperm population of normal motile sperms. Also, the new method is simple and does not require centrifugation step or any chemicals.