Establishment of a Human Hepatocyte Line That Supports in Vitro Development of the Exo-Erythrocytic Stages of the Malaria Parasites Plasmodium Falciparum and P. Vivax

Abstract

Our understanding of the biology of malaria parasite liver stages is limited because of the lack of efficient in vitro systems that support the exo-erythrocytic (EE) development of the parasite. We report the development of a new hepatocyte line (HC-04) from normal human liver cells. The HC-04 cells have proliferated in hormone-free medium for more than 200 passages. The cells were hyperdiploid, resembled liver parenchymal cells, and synthesized major liver-specific proteins and enzymes. Using Plasmodium falciparum and P. vivax sporozoites harvested from salivary glands of infected mosquitoes, we showed that HC-04 cells supported the complete EE development of these two most prevalent human malaria parasites. The EE parasites attained full maturation as shown by their infectivity to human erythrocytes. The infection rates of the liver cells were estimated to be 0.066% and 0.041% for P. falciparum and P. vivax, respectively. As the first human hepatocyte line known to support complete EE development of both P. falciparum and P. vivax, HC-04 will provide an experimental model that can be used for studying the biology of liver stage malaria parasites.

Preerythrocytic, live-attenuated Plasmodium falciparum vaccine candidates by design

“…Further analysis of the human parasite preerythrocytic stages has been challenging because no practical animal models for in vivo evaluation of liver infection exist. Nonetheless, liver infection can be modeled in cell culture, and we made use of the HC-04 continuous hepatocytic cell line that was shown to support complete liver-stage development of P. falciparum (21). Cell infection rates of the p52 Ϫ and p36 Ϫ lines were comparable with those of WT P. falciparum, indicating that the corresponding protein functions did not support host cell entry.…”

“…We investigated the ability of p52 Ϫ and p36 Ϫ sporozoites to invade host cells in vitro by using the HC-04 cell line, which supports invasion and complete liver-stage development of P. falciparum (21). Invasion was assessed microscopically by counting the number of cells invaded by sporozoites.…”

Neglect of Plasmodium vivax malaria

“…The expense and risk of such work usually requires solid preclinical studies as a foundation. Recent improvements with in vitro assays of drug activity against P. vivax (a rare example of a significant advance in research on this parasite) [60][61][62][63] at least offer the means of investigation of therapies in which the parasite can be obtained with relative ease. Despite evidence of resistance to CQ, and a reasonable forecast of further deterioration, clinical investigation of alternative treatments for vivax malaria resistant to CQ rarely occurs.…”

Rubescins A, B and C: New Havanensin Type Limonoids from Root Bark of <i>Trichilia rubescens</i> (Meliaceae)

“…Rubescin Table 2) and 13 C-NMR (see Table 1 Table 2) and 13 C-NMR data (see Table 1 Table 2) and 13 C-NMR data (see Table 1 19) and characterized, 20) were obtained from Dr. Urs A. Boelsterli. Cells were maintained in Dulbecco's modified Eagle's medium (DMEM) (Hyclone, Fisher Scientific, PA, U.S.A.) supplemented with 10% heat-inactivated fetal bovine serum, penicillin-streptomycin cocktail purchased from Gibco in a humidified incubator with 5% CO 2 at 37°C.…”