Permeable and non-permeable cryoprotectant-free cryopreservation of larger volumes native human semen via non-wettable rapeseed oil soot coatings

BACKGROUND: The scientific advance in cryobiology allows the cryostorage of human semen without the use of toxic permeable cryoprotectants. To do this, the cellular suspensions are supplemented with non-permeable cryoprotective agents that possess mild cytotoxicity. Alternatively, the freezing is executed in vitrification solutions and preservation extenders, with preliminary selected spermatozoa via density-gradient centrifugation and swim-up techniques, although these procedures sometimes cause sperm DNA fragmentation. OBJECTIVE: To introduce unique results concerning the cryopreservation of larger volumes native human semen (above 20‐30 μL) on water-repellent soot-coated surfaces, eliminating the involvement of any freezing extenders and formulations. RESULTS: The natural biomolecular matrix of seminal plasma combined with the icephobicity of rapeseed oil soot promoted the survival of over 5,500,000 forward-moving spermatozoa in 1 mL liquefied ejaculate. CONCLUSION: The future improvement of this technology may facilitate the assisted human reproduction, helping to solve the demographic problem in Europe.