Boar sperm changes after sorting and encapsulation in barium alginate membranes

A routine use of boar sexed semen is limited by the long sorting time necessary to obtain an adequate number of sexed spermatozoa for artificial insemination and by the high susceptibility of spermatozoa of this species to damages induced by sorting procedure and subsequent cryopreservation. The aim of this work was to study the impact of encapsulation in barium alginate membrane on sorted boar spermatozoa by evaluating membrane integrity, chlortetracycline (CTC) staining patterns, protein tyrosine phosphorylation and Hsp70 immunolocalization during storage over 72h in liquid or encapsulated form. The encapsulation procedure significantly (p<0.05) decreased the overall membrane integrity of control unsorted semen (81.8 vs 57.4, CTR vs CPS), but did not negatively affect the overall viability and the CTC staining patterns of sorted encapsulated cells. Moreover encapsulation significantly decreased (P < 0.05) the overall phosphotyrosin A pattern cell percentage in unsorted (98.4 vs 92.6, CTR vs CPS) but not in sorted semen (64.0 vs 74.2 SORT CTR vs SORT CPS). As for Hsp70, the overall percentage of cells displaying the different patterns was significantly influenced (p<0.05) by treatment but not by storage time. The sorting procedure seems to induce the major changes while encapsulation tends to exert a protective effect on sorted semen by increasing the percentage of spermatozoa displaying the T pattern (2.8 vs 24.3 SORT CTR vs SORT CPS). In conclusion, our data confirm that the damaging impact of the encapsulation in barium alginate capsules seems to be limited when compared to that of the sorting procedure and, moreover, the association of the two procedures does not result in an algebraic sum of the negative effects. These results suggest the possibility of a future utilization of the encapsulation technology in order to store sorted spermatozoa and permit their controlled release in the female genital tract.