Biomechanical properties of red blood cells infected by Plasmodium berghei ANKA

Malaria is a pathogenic disease in mammal species and typically causes destruction of red blood cells (RBCs). The malaria-infected RBCs undergoes alterations in morphology and its rheological properties, and the altered rheological properties of RBCs have a significant impact on disease pathophysiology. In this study, we investigated detailed topological and biomechanical properties of RBCs infected with malaria Plasmodium berghei ANKA using atomic force microscopy. Mouse (BALB/c) RBCs were obtained on Days 4, 10, and 14 after infection. We found that malaria-infected RBCs changed significantly in shape. The RBCs maintained a biconcave disk shape until Day 4 after infection and then became lopsided on Day 7 after infection. The central region of RBCs began to swell beginning on Day 10 after infection. More schizont stages were present on Days 10 and 14 compared with on Day 4. The malaria-infected RBCs also showed changes in mechanical properties and the cytoskeleton. The stiffness of infected RBCs increased 4.4-4.6-fold and their cytoskeletal F-actin level increased 18.99-67.85% compared with the control cells. The increase in F-actin depending on infection time was in good agreement with the increased stiffness of infected RBCs. Because more schizont stages were found at a late period of infection at Days 10 and 14, the significant changes in biomechanical properties might contribute to the destruction of RBCs, possibly resulting in the release of merozoites into the blood circulation.