Observation of the in vitro invasion of intestinal epithelial cells by Trichinella spiralis larvae and their development in those cells.

Objective To observe the in vitro invasion of intestinal epithelial cells by Trichinella spiralis larvae and their development in those cells.Methods T.spiralis muscle larvae were incubated in rat intestinal contents or mouse bile for 2 h and then inoculated into semisolid medium(DMEM/F12 complete medium +1.75% agarose),semisolid medium+T84 cells,DMEM/F12 complete medium+T84 cells,or semisolid medium(high glucose DMEM complete medium +1.75% agarose) + Caco-2 cells.Cultures were incubated at 37 ℃ in 5% CO2 for 24 h,and then the L1 and L2-L4 larvae in the cell monolayer were observed and counted.Results When the larvae incubated in gut contents and bile were inoculated into semisolid medium +Caco-2 cells,the percentages of L2-L4 larvae were 50% and 34.78%,respectively(χ2=0.836,P0.05);both were higher than the percentages incubated in RPMI-1640(8.70%)(χ12=5.978,χ22=4.600,P0.05).After incubation in gut contents,the percentage(40%) of L2-L4 larvae cultured in semisolid medium+T84 cells was higher than that(4.76%) cultured in semisolid medium(χ2=10.947,P0.05).The difference between the percentage of the L2-L4 larvae in the T84(40%) and Caco-2(50%) monolayer was not statistically significant(χ2=0.546,P0.05).The L2-L4 larvae were not observed in complete medium +T84 cells.Larvae invaded the T84 and Caco-2 monolayer,migrated through the monolayer,and left obvious trails.After larvae were cultured for 37 h and 42 h,one female adult and three male adults were observed.Conclusion After incubation in intestinal contents or bile,T.spiralis larvae inoculated into semisolid medium invaded intestinal epithelial cells and developed in vitro.