Hyaluronic acid (Sperm Select) improves retention of sperm motility and velocity in normospermic and oligospermic specimens.

The effects of Sperm Select (Pharmacia AB, Uppsala, Sweden), a hyaluronic acid medium, on the motility and membrane integrity properties of sperm were studied. In 15 normospermic specimens after overnight incubation, the motility parameters in the control versus the Sperm Select group were as follows (mean +/- SEM): motility, 18.8% +/- 2.8% versus 27.4% +/- 2.9%; velocity, 21.5 +/- 2.4 versus 27.2 +/- 2.2 microns/s; linearity, 3.8 +/- 0.3 versus 4.4 +/- 0.2; lateral head displacement, 1.5 +/- 0.2 versus 1.9 +/- 0.1 microns; and tail beat/cross frequency, 8.8 +/- 1.3 versus 10.8 +/- 1.4 Hz. The density of motile sperm was 10.8 +/- 2.3 versus 18.5 +/- 2.5 X 10(6) sperm/mL. Finally, the velocity coefficient, the multiple of the sperm motility and linear velocity, was 4.6 +/- 1.1 versus 8.1 +/- 1.4. However, we found no Sperm Select related differences when testing sperm membrane integrity with hypoosmotic swelling and supravital staining. Thus, Sperm Select improves the retention of sperm motility (most prominently velocity) apparently due to a direct action of hyaluronic acid on sperm metabolism or contractility rather than to preservation of sperm membrane integrity. In 20 oligospermic specimens, Sperm Select caused similar improvements in sperm motility, and the duration of motility could be predicted from the degree of enhancement in sperm velocity after short-term Sperm Select exposure. A modified Sperm Select protocol is described that further increases motile sperm yield without a centrifugation step.