Amebiasis, which is caused by Entamoeba histolytica infection, is the third deadliest parasitic disease globally. Proliferation of E. histolytica trophozoites and their invasion into the host tissues cause amebiasis symptoms and pathogenesis. E. histolytica trophozoites are also important in multiple biology research topics. Therefore, E. histolytica trophozoites are a common subject in academic as well as clinical fields. A standard method for in vitro culture of E. histolytica trophozoites is well established. By contrast, a widely adopted practical method for cryopreservation of E. histolytica trophozoites is not yet available. This hampers the advancement of amebic research, as the required E. histolytica trophozoite lines sometimes cannot be revived from cryopreservation. In this study, we varied parameters critical to the revival rate, namely, cell density, cooling rate, freezing reagent, and freezing profile, and present an optimized cryopreservation method for E. histolytica trophozoites, which gives reproducibly high revival rates.
Kazama et al. (Mon,) studied this question.