Recovery of high-quality sperm after cryopreservation in the common marmoset (Callithrix jacchus)†

The common marmoset (Callithrix jacchus) is a promising animal model for preclinical biomedical research due to genetic, anatomic, and physiological similarity to humans. Assisted reproductive technologies can maximize the potential of captive research marmoset colonies, including preservation and propagation of genetically desirable or modified individuals. The literature on marmoset sperm cryopreservation is sparse, and limited assessments have been applied to the existing protocols that have yet to be fully optimized. In this study, we refined and standardized established cryopreservation components for common marmoset sperm, performed a comprehensive evaluation of frozen-thawed sperm quality, and identified accessible components for widespread adoption. While sperm were significantly less motile following cryopreservation compared to fresh sperm, no significant differences were detected across different cryostorage durations up to 6 months. Moreover, the average post-thaw recovery rates were 66% (total motility) and 36% (progressive motility), exceeding previously reported outcomes. Fresh and frozen-thawed sperm exhibited no significant differences in key structural parameters, including acrosome integrity and DNA fragmentation. The improved marmoset sperm cryopreservation protocol reported here will facilitate the sharing of genetically diverse and/or gene-edited sperm for research and colony management and provide a robust foundation for future studies aimed at enhancing the outcomes of frozen-thawed sperm in this and other NHP species.