Comparative evaluation of two density gradient preparations for sperm separation for medically assisted conception

To evaluate and optimize the sperm separation efficiency of a novel silane-coated silica bead (Puresperm), serial studies were carried out to compare the various sperm parameters between: (i) three-layer (90%-70%-40%) Puresperm and three-layer (90%-70%-40%) conventional polyvinylpyrrolidone (PVP)-coated silica bead (Percoll) gradients; (ii) three-layer (90%-70%-40%) and two-layer (90%-45%) Puresperm gradients and separately the same for Percoll; acid (iii) large (3.0 ml) and small (0.75 ml) semen loading volumes on three-layer Puresperm gradients. Normozoospermic semen samples were treated and analysed in 12 replicates for each experiment, Manual evaluation of concentration, percentage motility, percentage vitality, percentage normal morphology; computer-assisted semen analysis evaluation of concentration, percentage motility, grade of motility, motion characteristics (curvilinear velocity, linearity, amplitude of lateral head velocity, beat cross frequency, percentage hyperactivation); and yields from the initial semen samples were compared. Percoll was found to be superior to Puresperm in concentration, percentage motility, percentage vitality and yields after three-layer density gradient centrifugation, There were no significant differences in sperm parameters between two- and three-layer Percoll gradients, but three-layer Puresperm gradients behaved significantly better than two-layer gradients, Large semen volume roads on three-layer Puresperm gradients resulted in greater sperm concentrations, percentage motility, percentage vitality and percentage normal morphology, but small semen volume loads produced greater yields of good-quality spermatozoa, In the light of Percoll being withdrawn from the shelf for the use of assisted reproduction because of the presence of PVP, three layer Puresperm gradients with large semen loading volumes appear to be an attractive alternative for sperm separation in medically assisted conception.