Temperature variable and the efficiency of sperm mediated transfection of HPV16 DNA into cells

Aim: To pretreat sperm at various temperatures before exposure to human papillomavirus (HPV) 16 DNA fragments and to assess the efficiency of HPV carrier sperm to transfect cumulus cells. Methods: Cumulus cells from follicular aspirates were obtained, pooled and divided into culture dishes containing Sybr Gold-stained HPV DNA carrying sperm that were either pretreated at 4°C, 37°C or 40°C (n = 5). The cells were incubated in 5% CO₂ in air mixture at 37°C for 24 hours. The efficiency of sperm to take up fluorescent HPV DNA was determined at hour 0. After incubation, cumulus cell viability was assessed using the eosin method and the percentages of fluorescent cumulus cells determined. Results: Over half of all the cumulus cells became fluorescent with the highest percentage in the 37°C group. Sperm pretreated at 4°C had the greatest amount of HPV DNA fragments. Total sperm motility was similar for the 3 pretreatment groups. There were no differences in cumulus viability among the groups. Conclusion: Sperm pretreated at 37°C transferred the greatest amount of fluorescent HPV DNA fragments to the cumulus cells. The HPV DNA was observed in the nuclear and cytoplasmic compartments. The data suggested the possibility of sperm as a vector for the transmission of HPV DNA to the cumulus cells surrounding ovulated oocytes, which might lead to early implantation failures.