CONDITIONED MEDIUM FROM HUMAN CUMULUS-OOPHORUS CELLS STIMULATES HUMANSPERM VELOCITY

The objective of this study was to determine whether the cumulus oopho rus cells surrounding the human oocyte release a factor(s) that stimul ates sperm velocity. Medium from in vitro fertilization (IVF) that was exposed to cumulus/oocyte complexes was tested for its ability to sti mulate sperm velocity by use of a computerized sperm motion analyzer. In subsequent experiments, primary cultures of cumulus cells, granulos a cells, and ovarian cancer cells were established, and conditioned me dium from these cells was assessed for sperm velocity-stimulating acti vity. In the initial series of assays using four sperm donors, cumulus /oocyte complex-conditioned medium from IVF increased sperm curvilinea r velocity and amplitude of lateral head displacement by an average of 12.3% and 19.3% (P < 0.0001), respectively, compared to medium from I VF that was not exposed to cumulus/oocyte complexes. These results wer e confirmed in a subsequent, more extensive series of assays using a s ingle sperm donor. Testing of conditioned media after 24 h of primary cell culture showed that cumulus-conditioned medium consistently stimu lated curvilinear velocity (8.8% increase) and lateral head amplitude (18.7% increase) compared to unconditioned medium (p < 0.0001) in a ma nner similar to cumulus/oocyte complex-conditioned medium. In contrast , granulosa-conditioned medium and ovarian cancer cell-conditioned med ium did not stimulate curvilinear velocity and lateral head amplitude compared to unconditioned medium. The ability of cumulus-conditioned m edium to stimulate curvilinear velocity and lateral head amplitude dec lined gradually during the 5-day culture period. Nevertheless, the res ults indicate that the cumulus released velocity-stimulating activity throughout the culture period. It is concluded that cumulus oophorus c ells released a factor(s) that stimulated both sperm velocity and ampl itude of lateral head displacement. This finding is consistent with th e hypothesis that the cumulus/ oocyte complex modulates sperm velocity and may have a role in fertilization.