A viscoelastic model of phagosome motion within cells based on cytomagnetometric measurements

Nemoto, Iku; Moeller, Winfried

doi:10.1109/10.821751

Cited by 17 publications

(18 citation statements)

References 15 publications

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“…This phenomenon, called relaxation, is attributed to rotation (misalignment) of particle-containing phagosomes and phagolysosomes [8,18,19] as well as phagosomal transport along microfilaments and microtubules [20,21]. The latter report also confirms that relaxation requires an intact cytoskeleton and active ATP production.…”

Section: Introductionmentioning

confidence: 69%

Diminished organelle motion in murine Kupffer cells during the erythrocytic stage of malaria

Bellows

Molina

Brain

2010

J. R. Soc. Interface.

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Parasitized erythrocytes are ingested by murine hepatic macrophages during malaria infection. We non-invasively monitored how this altered the motion of intracellular phagosomes in Kupffer cells using magnetometry. Submicrometric gFe 2 O 3 particles were injected prior to malaria infection. They were cleared from the blood, primarily by Kupffer cells, and retained within their phagosomes. The mice were periodically magnetized. After removing this external magnet, the aligned iron particles created a remnant magnetic field (RMF) which then decayed (relaxation), reflecting the motion of particle-containing phagosomes. After baseline measurements of relaxation, the mice were injected intravenously with Plasmodium chabaudi-parasitized or normal murine red blood cells (RBCs). During the next 15 days, relaxation measurements, parasitaemia and haematocrit values were monitored. At 6 days post injection with 3 Â 10 7 parasitized RBCs, relaxation rates had decreased. At this time, all mice had parasitaemias greater than 58 per cent and haematocrits less than 20 per cent. At day 7, while the parasitaemias were declining, the rate of relaxation continued to decrease. Throughout the experiment, relaxation remained constant in animals injected with normal RBCs. Electron microscopy revealed Kupffer cells filled with damaged and parasitized erythrocytes, and haemoglobin degradation pigment. We conclude that ingestion and metabolism of parasitized erythrocytes by liver macrophages during malaria infection decreases their organelle motion with likely consequences of compromised host defences.

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Section: Introductionmentioning

confidence: 69%

Diminished organelle motion in murine Kupffer cells during the erythrocytic stage of malaria

Bellows

Molina

Brain

2010

J. R. Soc. Interface.

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“…the phagosomes and to induce rotational random kicks to the phagosome [33,39,51,52]. A hydrodynamic relaxation model was developed under the assumption that the intracellular randomization energy E r behaves like thermal energy kT, implying a rotational Brownian motion process together with an exponential decay in a Newtonian viscosity.…”

Section: Figurementioning

confidence: 99%

385 Ultrafine particles cause cytoskeletal dysfunctions in macrophages: Role of intracellular calcium

Stone¹,

Brown²,

Möller³

et al. 2003

Toxicology Letters

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“…The pulse magnetizing field does not mechanically rotate the phagosomes. It is shown [10] that the variance of θ after pulse magnetization ( 0…”

Section: Cytomagnetometric Measurement Of the Energy Of The Intracellmentioning

confidence: 99%

“…The first model in [1] consisted of E r and apparent viscosity η. Viscoelastic components were added to the model and the behavior of the model was examined in detail in [10]. Experimental data were treated with the viscoelastic model but in a somewhat simpler way in [11].…”

Section: Introductionmentioning

confidence: 99%

“…Later, macrophages in vitro were used and it was shown that the relaxation process was indeed due to the intracellular movements within cells [2][3][4]. Since then several researchers have used this technique for studying some aspects of the biomechanics of cells [5][6][7][8][9][10][11]. Of recent interest is the study by Wang et al [8] on the transduction of mechanical stimuli on the outer surface of the cell to the inner cytoskeletal structure.…”

Section: Introductionmentioning

confidence: 99%

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Cytomagnetometric measurement of the energy of the intracellular movements

Nemoto

Takahashi

Matsuzaki

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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Abstract-Magnetic particles were given to macrophage-like cultured cells J774A.1 to perform cytomagnetometry in which the magnetic field from the cells was measured and the mechanical parameters of the cytoplasm and the energy E r of the intracellular movement were estimated. The response of the cells to ATP-synthesis inhibitor MIA measured by cytomagnetometry was intriguing; the energy E r became larger contrary to our expectation. We have been searching for the reason for this phenomenon by the immunofluorescent microscopy and the use of other drugs and cell types. The results have yielded some clue to the question, which we discuss in the present paper. I. INTRODUCTIONCytomagnetometry has been used to investigate mechanical properties of the cytoplasm for nearly 20 years. It was first conjectured by Nemoto[1] that the relaxation phenomenon observed in the magnetic field from the human lung which inhaled magnetic dust was due to the intracellular movements of the alveolar macrophages in the lung which randomized the direction of the magnetic moments of the particles within the cells which had been magnetized by an external magnetic field immediately before the relaxation measurement. The energy responsible for the relaxation process, which we designate as E r was also estimated by the method of secondary magnetization of the lung. Later, macrophages in vitro were used and it was shown that the relaxation process was indeed due to the intracellular movements within cells [2][3][4]. Since then several researchers have used this technique for studying some aspects of the biomechanics of cells [5][6][7][8][9][10][11]. Of recent interest is the study by Wang et al. [8] on the transduction of mechanical stimuli on the outer surface of the cell to the inner cytoskeletal structure.In [1] the measurement method of E r was proposed based on the simplest model in which a magnetic particle goes under rotational Brownian motion which is impeded by apparent viscosity of the cytoplasm. This model seemed to be enough for estimating E r although other experimental results showed that phagosomes containing the particles experience elasticity as well as viscosity and the randomizing force.Models have been proposed for cytomagnetometry. The first model in [1] consisted of E r and apparent viscosity η. Viscoelastic components were added to the model and the behavior of the model was examined in detail in [10]. Experimental data were treated with the viscoelastic model but in a somewhat simpler way in [11]. A different model using viscoelasticity was proposed but not discussed here.In the present paper, we present our recent result with J774A.1 cells which showed intriguing behavior of E r when MIA was added. MIA is known to inhibit the glycolysis pathway in the ATP synthesis in cells. In the present paper, we present the results of the cytomagnetometric measurements and the microscopic observations of the cytoskeleton to discuss the strange behavior of E r . II. MODEL 1) Energy E r Responsible for Relaxation:Cytomagnetometry is p...

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A viscoelastic model of phagosome motion within cells based on cytomagnetometric measurements

Cited by 17 publications

References 15 publications

Diminished organelle motion in murine Kupffer cells during the erythrocytic stage of malaria

Diminished organelle motion in murine Kupffer cells during the erythrocytic stage of malaria

385 Ultrafine particles cause cytoskeletal dysfunctions in macrophages: Role of intracellular calcium

Cytomagnetometric measurement of the energy of the intracellular movements

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