HYALURONIC-ACID SUBSTANTIALLY INCREASES THE RETENTION OF MOTILITY IN CRYOPRESERVED THAWED HUMAN SPERMATOZOA/

We have demonstrated previously that hyaluronic acid (HA) improves the velocity and the retention of motility in freshly ejaculated human sp ermatozoa, In the present work, we examined the effect of HA on cryopr eserved/thawed spermatozoa in four paradigms: (i) effect of HA on sper m motility and velocity in semen; (ii) stabilizing effect of HA after 4 h of incubation when the decline of sperm motility is already detect able; (iii) the duration of improved motility after the separation of spermatozoa from HA by Percoll gradient centrifugation; and (iv) motil ity of sperm cryopreserved in the presence of HA, HA improved the rete ntion of sperm motility in thawed spermatozoa. Indeed, the motility va lues after 30 h were similar to 100% higher in the HA compared with th e control samples, This effect of HA was also evident in the stabiliza tion of spermatozoa with already declining motility, After removal of the HA from the incubation medium, significantly increased motility in the HA-exposed spermatozoa was still detectable for at least 4 h, Cry opreservation of spermatozoa in the presence of HA did not improve the recovery of motility, The data indicate that HA improves the retentio n of motility of cryopreserved/thawed spermatozoa, even after the remo val of HA from the incubation medium, The utilization of HA will proba bly prove beneficial in assisted reproduction: in intrauterine insemin ation and in in-vitro fertilization (IVF), the extended sperm motility and velocity will enhance the fertilizing efficiency; in intracytopla smic sperm injection (ICSI), the improved motility will facilitate the identification of viable spermatozoa. Because HA is a physiological c omponent of the cumulus and of the female and male reproductive tracts , administration of HA should not cause ethical concerns.