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Results: 5

1.
Figure 1

Figure 1. From: Differences in the Microrheology of Human Embryonic Stem Cells and Human Induced Pluripotent Stem Cells.

High-resolution trajectories of individual beads embedded in the cytoplasm of human parental fibroblasts, derived hiPS cells, and latB-treated fibroblasts. (A and B) Typical random displacements of 1.0-μm diameter beads embedded in the cytoplasm of parental IMR90 human fibroblasts can be either free-diffusing (A) or highly restricted (B). Typical displacements of beads embedded in the cytoplasm of (C) hiPS cells and (D) latB-treated IMR90 cells, which always undergo free diffusion. The centroid position of each bead was determined nine times per second for 22.2 s. Scale bars, 0.1 μm.

Brian R. Daniels, et al. Biophys J. 2010 December 1;99(11):3563-3570.
2.
Figure 2

Figure 2. From: Differences in the Microrheology of Human Embryonic Stem Cells and Human Induced Pluripotent Stem Cells.

MSDs of beads in parental human fibroblasts, derived hiPS cells, and hES cells. (AE) MSDs of individual beads embedded in the cytoplasm of parental IMR90 fibroblasts (A, n = 59), derived hiPS cells (B, n = 103), latB-treated IMR90 fibroblasts (C, n = 103), hES cells (D, n = 143), and latB-treated hES cells (E, n = 126). Time-lag-dependent MSDs exhibiting a slope <1 on a log-log plot (A, D, and E) are subdiffusive and indicative of a cytoplasm that is locally elastic, whereas slopes of 1 indicate a diffusive environment. Note the complete absence of subdiffusive MSDs in hiPS cells and the reduction of subdiffusive MSDs in latB-treated hES cells relative to untreated hES cells.

Brian R. Daniels, et al. Biophys J. 2010 December 1;99(11):3563-3570.
3.
Figure 3

Figure 3. From: Differences in the Microrheology of Human Embryonic Stem Cells and Human Induced Pluripotent Stem Cells.

Beads exhibit restricted motion in parental human fibroblasts and hES cells. (AL) Distributions of MSD values at both 1-s (AE) and 5-s (GK) time-lags of beads embedded in the cytoplasm of IMR90 fibroblasts (A and G), derived hiPS cells (B and H), latB-treated IMR90 fibroblasts (C and I), hES cells (D and J), and latB-treated hES cells (E and K). Histograms of these distributions indicate a disproportionately high number of small MSDs in IMR90 cells compared to hiPS at both 1-s and 5-s time-lags, as well as a larger number of small MSDs in hES cells compared to hES cells treated with latB at both time-lags. Cumulative percentage plots (F and L) indicate the percentage of beads that fall within a specified limit MSD. A disproportionate majority of beads in IMR90 differentiated cells exhibit restricted motion as compared to beads in hiPS de-differentiated cells.

Brian R. Daniels, et al. Biophys J. 2010 December 1;99(11):3563-3570.
4.
Figure 5

Figure 5. From: Differences in the Microrheology of Human Embryonic Stem Cells and Human Induced Pluripotent Stem Cells.

Actin microfilaments confer elasticity to differentiated parental fibroblasts and hES cells. (A and B) IMR90 fibroblasts and hiPS cells exhibit significantly different microfilament architecture. IMR90 cells contain a rich internal microfilament network typical of cultured fibroblasts, whereas hiPS cells are largely devoid of internal actin filament structure, such as filament bundles, reminiscent of the undifferentiated C. elegans zygote (7). (C) Depolymerization of actin filaments by latB in IMR90 cells led to a marked decrease in their elasticity down to values found for hiPS cells. (D) Colonies of hES cells show a rich basal actin microfilament structure, similar to that of IMR90 cells. (E) LatB treatment of hES cells largely depolymerized the intracellular actin network, whereas cortical actin structures remained intact. Scale bar, 20 μm.

Brian R. Daniels, et al. Biophys J. 2010 December 1;99(11):3563-3570.
5.
Figure 4

Figure 4. From: Differences in the Microrheology of Human Embryonic Stem Cells and Human Induced Pluripotent Stem Cells.

Diffusion coefficient of nanoparticles and viscosity of the cytoplasm of parental fibroblasts, derived hiPS cells, and hES cells. (A) Viscous and elastic fractions of particles observed in each condition. Particles were classified as viscous if their MSDs at a time-lag of 10 s were ≥0.000125 μm2/s. (B) Mean diffusion coefficient, , of embedded beads. The MSDs of freely diffuse beads up to a time-lag of 1s were used to determine the bulk mean diffusion coefficient of beads in IMR90 and hiPS cells to be 0.00028 ± 0.00003 and 0.00054 ± 0.00004, μm2/s, respectively. Asterisks or indications of no significance (NS) correspond to P values of t-tests between IMR90 values and each respective column. (C) Cytoplasmic viscosity is inversely related to the diffusion coefficient through the Stokes-Einstein relationship (see text). The mean viscosities, , of IMR90 and hiPS cells are 24 ± 3 and 15 ± 1 Poise, respectively (P < 0.0001). Asterisks or indications of NS correspond to P values of t-tests between IMR90 values and each respective column. (D) Mean elastic modulus, , at 1 Hz calculated using only time-independent MSDs representative of elastic particles in each condition. Asterisks or indications of NS correspond to P values of t-tests between IMR90 values and each respective column.

Brian R. Daniels, et al. Biophys J. 2010 December 1;99(11):3563-3570.

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