Cryoprotectant-free vitrification of fish (Oncorhynchus mykiss) spermatozoa: first report
- Merino, O. - Sanchez, R. - Risopatron, J. - Isachenko, E. - Katkov, I. I. - Figueroa Villalobos, Elías - Valdebenito Isler, Iván - Mallmann, P. - Isachenko, V.
- Datos de publicación:
- Cryoprotectant-free - fish - membrane - spermatozoa - vitrification
- Migración Web of Science 
- The aims of this investigation were to test a novel technology comprising cryoprotectant-free vitrification of the spermatozoa of rainbow trout and to study the ability of sucrose and components of seminal plasma to protect these cells from cryo-injuries. Spermatozoa were isolated and vitrified using three different media: Group 1: standard buffer for fish spermatozoa, Cortland (R) medium (CM, control); Group 2: CM + 1% BSA + 40% seminal plasma; and Group 3: CM + 1% BSA + 40% seminal plasma + 0.125 m sucrose. For cooling, 20-mu l suspensions of cells from each group were dropped directly into liquid nitrogen. For warming, the spheres containing the cells were quickly submerged in CM + 1% BSA at 37 degrees C with gentle agitation. The quality of spermatozoa before and after vitrification was analysed by the evaluation of motility and cytoplasmic membrane integrity with SYBR-14/propidium iodide staining technique. Motility (86%, 81% and 82% for groups 1, 2 and 3, respectively) (P > 0.1) was not decreased significantly. At the same time, cytoplasmic membrane integrity of spermatozoa of Groups 1, 2 and 3 was changed significantly (30%, 87% and 76% respectively) (P < 0.05). All tested solutions can be used for vitrification of fish spermatozoa with good post-warming motility. However, cytoplasmic membrane integrity was maximal in Group 2 (CM + 1% BSA + 40% seminal plasma). In conclusion, this is the first report about successful cryoprotectant-free cryopreservation of fish spermatozoa by direct plunging into liquid nitrogen (vitrification). Vitrification of fish spermatozoa without permeable cryoprotectants is a prospective direction for investigations: these cells can be successfully vitrified with 1% BSA + 40% seminal plasma.