Small-volume vitrification for human spermatozoa in the absence of cryoprotectants by using Cryotop

Cryotop is a carrier that has been used successfully in the cryopreservation of
human spermatozoa. Here, we explored a novel method to vitrify human spermatozoa
without cryoprotective agents (CPAs) using Cryotop. Spermatozoa
from 21 Normozoospermic patients were collected and vitrified without CPAs
or with sucrose in small volume using Cryotop. The sperm recovery rate,
motility, viability, chromatin damage and DNA fragmentation were assessed.
No significant difference was observed in the sperm recovery rate and motility
rate between the spermatozoa cryopreserved without CPAs and with sucrose.
The post-thawed spermatozoa cryopreserved without CPAs had a higher viability
and lower damage to sperm chromatin and DNA than those cryopreserved
with sucrose. These results suggest that small numbers of human spermatozoa
can be successfully vitrified without CPAs using Cryotop.