The use of silane-coated silica particles for density gradient centrifugation in in-vitro fertilization

Silane-coated silica particles (PureSperm(R)) were evaluated as an alternat ive to Percoll for gradient separation of spermatozoa, for use in assisted reproduction. Recovery of motile and morphologically normal spermatozoa aft er using a four-layer Percoll and a two- and four-layer PureSperm(R) gradie nt respectively was recorded. In-vitro fertilization (IVF) results after us ing PureSperm(R) for the sperm preparation were also evaluated. No differen ce in sperm recovery or sperm motility was found when comparing the use of Percoll and the four-layer gradient of PureSperm(R). When using a two-layer PureSperm(R) gradient, motility was significantly decreased (P < 0.05) com pared to Percoll. Normal sperm morphology increased from 8-17.2% after usin g Percoll and to 12.7% and 11.4% after using a four-layer and a two-layer P ureSperm(R) gradient respectively. All gradient preparations showed a signi ficant decrease in the teratozoospermia index compared to the ejaculate (P < 0.01). No significant differences in IVF results regarding fertilization and pregnancy rates were found when PureSperm(R) or the swim-up technique w ere used for the sperm preparation. PureSperm(R) seems to be an acceptable alternative to Percoll but although the percentage of sperm recovery was hi gher after PureSperm(R) we still recommend the swim-up technique to be the first choice, as a higher percentage of progressive motile spermatozoa is o btained without using other chemicals than IVF culture medium.