Can a cumulus cell complex be used to select spermatozoa for assisted reproduction?

Since the onset of intracytoplasmic sperm injection, researchers have intensified the search for the ideal spermatozoa to be used for injection. The aim of this study was to record the functional role of cumulus cell interaction with human spermatozoa as far as capacitation, acrosome reaction, morphology, zona binding and chromatin packaging quality are concerned. Using a previously described cumulus oophorus model, we recorded specific sperm functional aspects of sperm populations that transverse a cumulus cells mass. Control spermatozoa were kept under similar experimental conditions in the culture media only. Results indicated cumulus cells to be beneficial to spermatozoa as far as functional and capacitational events are concerned. The mean percentage of morphologically normal spermatozoa in the control sample was 6.9%, while the spermatozoa that traversed the cumulus oophorus (test) had a significantly higher percentage of normal forms (mean 9.5%; P < or = 0.01). We observed a decline in the percentage of CMA3-positive spermatozoa when we compared the control population (49.1%) to the test, i.e. 38.4%, (P = <0.05), thus implying that the spermatozoa with good chromatin condensation increased during cumulus penetration. Significantly more (P < or = 0.01) acrosome-reacted spermatozoa were found in the penetrated spermatozoa (mean 23%) than in the control spermatozoa (mean 11%). The test spermatozoa had a higher zona binding capacity with significantly more (P < or = 0.01) tightly bound spermatozoa on the hemizona (61 +/- 15) than the control spermatozoa (47 +/- 18). In the absence of sophisticated and expensive sperm selection products, the use of a cumulus model to select spermatozoa for intracellular sperm injection seems to be an alternative method.