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Updated: Jun 16, 2026
Separation of Plasmodium falciparum Late Stage-infected Erythrocytes by Magnetic Means
Published on: March 2, 2013
Optimized high gradient magnetic separation for isolation of Plasmodium-infected red blood cells
Sebastian C Bhakdi1, Annette Ottinger, Sangdao Somsri
1Department of Pathobiology, Faculty of Science, Mahidol University, Bangkok, Thailand. sbhakdi@gmail.com
Background:
Highly purified infected red blood cells (irbc), or highly synchronized parasite cultures, are regularly required in malaria research. Conventional isolation and synchronization rely on density and osmotic fragility of irbc, respectively. High gradient magnetic separation (HGMS) offers an alternative based on intrinsic magnetic properties of irbc, avoiding exposure to chemicals and osmotic stress. Successful HGMS concentration in malaria research was previously reported using polymer coated columns, while HGMS depletion has not been described yet. This study presents a new approach to both HGMS concentration and depletion in malaria research, rendering polymer coating unnecessary.
Methods:
A dipole magnet generating a strong homogenous field was custom assembled. Polypropylene syringes were fitted with one-way stopcocks and filled with stainless steel wool. Rbc from Plasmodium falciparum cultures were resuspended in density and viscosity optimized HGMS buffers and HGMS processed. Purification and depletion results were analysed by flow cytometer and light microscopy. Viability was evaluated by calculating the infection rate after re-culturing of isolates.
Results:
In HGMS concentration, purity of irbc isolates from asynchronous cultures consistently ranged from 94.8% to 98.4% (mean 95.7%). With further optimization, over 90% of isolated irbc contained segmented schizonts. Processing time was less than 45 min. Reinfection rates ranged from 21.0% to 56.4%. In HGMS depletion, results were comparable to treatment with sorbitol, as demonstrated by essentially identical development of cultures.
Conclusion:
The novel HGMS concentration procedure achieves high purities of segmented stage irbc from standard asynchronous cultures, and is the first HGMS depletion alternative to sorbitol lysis. It represents a simple and highly efficient alternative to conventional irbc concentration and synchronization methods.
Insights
This study introduces a novel, polymer-free high gradient magnetic separation (HGMS) method for malaria research. This technique efficiently concentrates infected red blood cells (irbc) and depletes them, offering a superior alternative to traditional methods.
Area of Science:
- Malariology
- Parasitology
- Biotechnology
Background:
- Purified infected red blood cells (irbc) and synchronized parasite cultures are crucial for malaria research.
- Conventional methods for irbc isolation and synchronization utilize density or osmotic fragility, which can stress cells.
- High gradient magnetic separation (HGMS) offers a chemical-free alternative using intrinsic magnetic properties of irbc.
Purpose of the Study:
- To develop and validate a novel, polymer-free HGMS approach for both concentration and depletion of irbc.
- To establish an efficient and simple alternative to conventional malaria research techniques.
Main Methods:
- Custom assembly of a dipole magnet for a strong, homogenous field.
- Utilized polypropylene syringes packed with stainless steel wool as HGMS columns.
- Resuspended Plasmodium falciparum infected red blood cells in optimized HGMS buffers for processing.
- Analyzed purification and depletion efficiency using flow cytometry, light microscopy, and re-culturing for viability assessment.
Main Results:
- Achieved high purity of irbc isolates, ranging from 94.8% to 98.4% (mean 95.7%) using HGMS concentration.
- Optimized protocol yielded over 90% segmented schizonts in isolated irbc within 45 minutes.
- HGMS depletion results were comparable to sorbitol lysis, showing similar parasite development in cultures.
- Reinfection rates after isolation ranged from 21.0% to 56.4%.
Conclusions:
- The novel HGMS concentration method provides high purity of segmented stage irbc from asynchronous cultures.
- This study presents the first HGMS depletion method as an alternative to sorbitol lysis.
- The developed HGMS technique is a simple, efficient, and effective alternative to conventional irbc concentration and synchronization methods in malaria research.
