From -196°C to -80°C: redefining standards in sperm biobanking technology

The preservation of spermatozoa through cryopreservation is a cornerstone of reproductive medicine, genetic biodiversity conservation and biomedical research. Traditionally, liquid nitrogen (LN2) storage at -196°C has been considered the gold standard for sperm biobanking. The high costs, logistical challenges and safety concerns associated with LN2, however, have prompted a reevaluation of alternative cryopreservation methods. This review traces the historical evolution of sperm cryopreservation, from its inception in 1938 to modern technological advancements, and proposes a paradigm shift towards ultra-low freezers operating at -80°C. Emerging evidence suggests that ultra-low freezers offer a cost-effective, sustainable and accessible alternative for sperm biobanking, particularly benefiting research institutions in low- and middle-income countries. Comparative analyses indicate that spermatozoa stored at -80°C retain fertilization potential over extended periods, challenging long-standing assumptions about the necessity of LN2. Additionally, the integration of cryoprotectants and antioxidants could further enhance the viability of spermatozoa stored in ultra-low freezers, mitigating concerns about DNA integrity and oxidative stress. By decentralizing sperm biobanking and reducing dependence on LN2, this approach fosters a more inclusive, resilient and environmentally sustainable system for the preservation of genetic resources.