Tomocube microscope advances Malaria research

Editorial

Rebecca Pool

Wednesday, September 4, 2019 - 12:15
Image: 3D RI tomograms of red blood cells infected by Plasmodium falciparum, a deadly protozoan parasite that cause malaria in humans.
 
Tomocube has developed label-free, 3D holotomography to quickly detect and monitor parasites within host cells, permitting the intricacies of parasite infection mechanisms and the host cell/parasite life cycle to be studied.
 
Numerous published studies reveal how researchers can easily observe morphological and chemical alterations of host cells due to the parasite infection without any transfection or dye staining.  
 
For example, using a Tomocube HT microscope, Park et al showed that the plasma membrane of an infected RBC (red blood cell) loses its deformability and becomes stiffer due to proteins secreted by the parasite altering the membrane cortex structure.
 
Although micropipette aspiration, optical tweezers, and cell filtration have been used to try to probe the cell membrane, these methods require highly complex instrumentation and also exert significant external forces on the cells, making it difficult to distinguish the intrinsic membrane properties.
 
In further studies, Kim et al also used the microscope to perform precise 3D RI measurements of haemoglobin digestion by the malaria parasites.
 
The team’s 3D RI tomograms of malaria infected RBCs also clearly reveal the shapes of various vacuoles as well as hemozoin, which can also be quantified.
 
According to Aubrey Lambert, Chief Marketing Officer at Tomocube: “Our holotomography microscope provides 3D localization of almost all sub-100 μm parasites without any preparation or staining, discriminating based on the high-RI value of their plasma membrane structure and cytoplasmic contents.”
 
3D RI tomograms of Plasmodium falciparum-infected red blood cells. (A) Ring stage. (B) Trophozoite stage. (C) Schizont stage. Top images show the cell membrane with a colour coding in red, bottom images are set for high transparency to make the intracellular structure visible. Modified from Kim K. et al. 
 
Also, a recently published study by Kim and his co-workers using the Tomocube HT-2H microscope showed 3D localization of intact Toxoplasma gondii infecting human epithelial and dendritic cells.
 
Results clearly demonstrated that the integration of holotomography and fluorescence microscopy benefits the characterisation of the molecular mechanism of specific genes or proteins in various parasites.
 
Holotomography uses laser interferometry to measure the 3D refractive index distribution within a specimen.
 
The method is suitable for observing small transparent objects, such as biological cells and their intracellular organelles, rapidly and quantitatively for analysis of an individual cell by calculating cellular dry mass, surface area, volume and other parameters.
 
  • Although the World Health Organisation (WHO) recorded an 18% decrease in malaria incidence between 2010 and 2017, and a corresponding estimated decrease of 28% in global malaria deaths in the same period, it should be recognised that an estimated 219 million people were still affected by this debilitating disease in 2017. 
 
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