scholarly journals Reticulocyte rigidity and passage through endothelial-like pores

Blood ◽  
1991 ◽  
Vol 78 (11) ◽  
pp. 3037-3042 ◽  
Author(s):  
RE Waugh
Keyword(s):  
Mechanical Properties ◽  
Bone Marrow ◽  
In Vitro Model ◽  
Gradient Centrifugation ◽  
The Mean ◽  
The Difference ◽  
Vitro Model ◽  
Mean Time ◽  
Endothelial Pores

Abstract The importance of cell rigidity in regulating the release of reticulocytes from the bone marrow has been investigated in a model system. Reticulocytes were obtained from phlebotomized rabbits and separated from whole blood by discontinuous density gradient centrifugation. The mechanical properties of the cells were tested. Using single-cell micromechanical techniques, the membrane elastic rigidity and the viscoelastic response of reticulocyte and mature cell populations were measured. The reticulocyte membranes were more rigid than the mature membranes, but the reticulocyte properties were heterogeneous, and some cells exhibited behavior indistinguishable from the mature cells. The mean time constant for viscoelastic recovery was the same for reticulocytes as for mature cells, but the variability within the reticulocyte population was greater. The possible influence of this increased rigidity on cell egress from the bone marrow was tested using an in vitro model of the thin endothelial pores found within the marrow. A silicon wafer approximately 0.1 microns in thickness and containing a small (1.2-microns diameter) pore in its center was cemented over the tip of a large (15.0-microns ID) micropipette. The passage of cells through the pore was observed as a function of the pressure across the pore. Consistent with the difference in mechanical properties, the reticulocytes required greater pressures (as great as 4.0 mm Hg compared with less than 1.0 mm Hg) and took longer to traverse the pore. These measurements support the postulate that deformability is important in the regulation of the release of cells from bone marrow.

scholarly journals Reticulocyte rigidity and passage through endothelial-like pores

Blood ◽  
1991 ◽  
Vol 78 (11) ◽  
pp. 3037-3042 ◽  
Author(s):  
RE Waugh
Keyword(s):  
Mechanical Properties ◽  
Bone Marrow ◽  
In Vitro Model ◽  
Gradient Centrifugation ◽  
The Mean ◽  
The Difference ◽  
Vitro Model ◽  
Mean Time ◽  
Endothelial Pores

The importance of cell rigidity in regulating the release of reticulocytes from the bone marrow has been investigated in a model system. Reticulocytes were obtained from phlebotomized rabbits and separated from whole blood by discontinuous density gradient centrifugation. The mechanical properties of the cells were tested. Using single-cell micromechanical techniques, the membrane elastic rigidity and the viscoelastic response of reticulocyte and mature cell populations were measured. The reticulocyte membranes were more rigid than the mature membranes, but the reticulocyte properties were heterogeneous, and some cells exhibited behavior indistinguishable from the mature cells. The mean time constant for viscoelastic recovery was the same for reticulocytes as for mature cells, but the variability within the reticulocyte population was greater. The possible influence of this increased rigidity on cell egress from the bone marrow was tested using an in vitro model of the thin endothelial pores found within the marrow. A silicon wafer approximately 0.1 microns in thickness and containing a small (1.2-microns diameter) pore in its center was cemented over the tip of a large (15.0-microns ID) micropipette. The passage of cells through the pore was observed as a function of the pressure across the pore. Consistent with the difference in mechanical properties, the reticulocytes required greater pressures (as great as 4.0 mm Hg compared with less than 1.0 mm Hg) and took longer to traverse the pore. These measurements support the postulate that deformability is important in the regulation of the release of cells from bone marrow.

scholarly journals Microcavity arrays as an in vitro model system of the bone marrow niche for hematopoietic stem cells

2016 ◽  
Vol 364 (3) ◽  
pp. 573-584 ◽  
Author(s):  
Patrick Wuchter ◽  
Rainer Saffrich ◽  
Stefan Giselbrecht ◽  
Cordula Nies ◽  
Hanna Lorig ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
In Vitro Model ◽  
Model System ◽  
Bone Marrow Niche ◽  
Hematopoietic Stem ◽  
In Vitro Model System ◽  
Vitro Model

Effects of adenosine on pressure-flow relationships in an in vitro model of compartment syndrome

1997 ◽  
Vol 82 (3) ◽  
pp. 755-759 ◽  
Author(s):  
Ian Shrier ◽  
Ari Baratz ◽  
Sheldon Magder
Keyword(s):  
Compartment Syndrome ◽  
Gastrocnemius Muscle ◽  
In Vitro Model ◽  
Adenosine Infusion ◽  
Pressure Flow ◽  
Adenosine Concentration ◽  
Flow Through ◽  
The Difference ◽  
Vitro Model

Shrier, Ian, Ari Baratz, and Sheldon Magder. Effects of adenosine on pressure-flow relationships in an in vitro model of compartment syndrome. J. Appl. Physiol. 82(3): 755–759, 1997.—Blood flow through skeletal muscle is best modeled with a vascular waterfall at the arteriolar level. Under these conditions, flow is determined by the difference between perfusion pressure (Pper) and the waterfall pressure (Pcrit), divided by the arterial resistance (Ra). By pump perfusing an isolated canine gastrocnemius muscle ( n = 6) after it was placed within an airtight box, with and without adenosine infusion, we observed an interaction between the pressure surrounding a muscle (as occurs in compartment syndrome) and baseline vascular tone. We titrated adenosine concentration to double baseline flow. We measured Pcrit and Ra at box pressures (Pbox), which resulted in 100 (Pbox = 0), 90, 75, and 50% flow without adenosine; and 200, 180, 150, 100, and 50% flow with adenosine. Without adenosine, each 10% decline in flow was associated with a 5.7 mmHg increase in Pcrit ( P < 0.01). With adenosine, the same decrease in flow was associated with a 2.6-mmHg increase in Pcrit ( P < 0.01). Values of Pcrit at 50% of flow were almost identical. Each 10% decrease in flow was also associated with 2.2% increase in Ra with or without adenosine ( P < 0.001). Ra decreased with adenosine infusion ( P < 0.05), and there was no interaction between adenosine and flow ( P > 0.9). We conclude that increases in pressure surrounding a muscle limit flow primarily through changes in Pcrit with and without adenosine-induced vasodilation. The interaction between Pbox and adenosine with respect to Pcrit but not Ra suggests that Pbox affects the tone of the vessels responsible for Pcrit but not Ra.

scholarly journals An in vitro model of erythroid egress in bone marrow

Blood ◽  
1986 ◽  
Vol 68 (1) ◽  
pp. 250-257 ◽  
Author(s):  
RE Waugh ◽  
M Sassi
Keyword(s):  
Bone Marrow ◽  
In Vitro Model ◽  
Physical Parameters ◽  
In Vitro System ◽  
Wafer Thickness ◽  
Pore Cells ◽  
A Cell ◽  
Vitro Model ◽  
Passage Times

Abstract An in vitro system has been developed that mimics the passage of erythrocytes from the bone marrow to the circulation. Bone marrow egress and its proper regulation are vital physiologic processes. However, because of the inaccessibility of the marrow, it is difficult to evaluate the various factors important in controlling these processes or even to define the precise mechanism by which egress occurs. The in vitro system has been designed to evaluate the importance of different physical parameters in regulating egress. It consists of a thin silicon wafer (thickness approximately equal to 1.0 micron) cemented over the tip of a large (15.0 micron ID) micropipette. The wafer contains a single circular pore. Cells were observed under the microscope as they passed through the pore under controlled pressures. The rate and duration of passage were obtained from videorecordings of the experiment. The measured passage times agreed well with the predictions of a simple analytical model of a cell passing through a thin aperture. The experimental results confirm the conclusion reached from the analysis that the pressures needed to drive a cell through the pore are well within the physiologic range, and the time needed to complete egress is typically less than 1.0 seconds. These results support the hypothesis that erythrocyte egress may be driven by a hydrostatic pressure difference across the pore.

Mechanical properties of various suture materials and placement patterns tested with surrogate in vitro model constructs simulating laryngeal advancement tie-forward procedures in horses

2014 ◽  
Vol 75 (5) ◽  
pp. 500-506 ◽  
Author(s):  
Marcos P. Santos ◽  
Santiago D. Gutierrez-Nibeyro ◽  
Gavin P. Horn ◽  
Amy J. Wagoner Johnson ◽  
Matthew C. Stewart ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
In Vitro Model ◽  
Suture Materials ◽  
Vitro Model

An In Vitro Model of Proliferating CLL Cells for Drug Sensitivity Analysis.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2956-2956
Author(s):  
K. Ganeshaguru ◽  
N. I. Folarin ◽  
R. J. Baker ◽  
A. M. Casanova ◽  
A. Bhimjiyani ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Lymph Nodes ◽  
Peripheral Blood ◽  
Drug Sensitivity ◽  
In Vitro Model ◽  
Survivin Expression ◽  
Lymphoid Cells ◽  
Malignant Cells ◽  
Vitro Model

Abstract B-cell chronic lymphocytic leukaemia (CLL) is a heterogeneous disease with a variable clinical course. The disease is characterised by the proliferation in the bone marrow and lymph node of a clonal population of CD5+ve cells that accumulates in the peripheral blood. Therefore, the characteristics of the proliferative compartment are important in determining the kinetics of disease progression in CLL and the sensitivity of the malignant cells to cytotoxic drugs. However, laboratory studies on drug sensitivity of CLL have been performed exclusively on resting circulating peripheral blood cells since it is not feasible to obtain cells from the proliferating pool in sufficient numbers for in vitro analysis. CLL cells can be stimulated to proliferate in vitro using CpG oligonucleotides (ODN) and other factors. The aim of the present study was to generate and validate an in vitro model using malignant cells from the peripheral blood of patients with CLL. The expression pattern of proteins eg., survivin in this model should mimic that in proliferating CLL cells in the bone marrow and lymph nodes. Survivin is a member of the family of inhibitor of apoptosis (IAP) proteins with an additional role in cell cycle progression. Survivin has been shown to be expressed in proliferating bone marrow and lymphoid cells. Cells from patients with CLL were activated for 72h with a combination of ODN (1μM), IL-2 (100u/ml) and CD40L (0.5μg/ml) (ODN*). Activated cells retained their characteristic CLL immunophenotype as determined by the continued expression of CD5, CD19, CD23 and CD25 (n=5). Cell proliferation was confirmed by increased incorporation of 3H-thymidine into DNA in activated cells (n=12). Novel findings in the ODN* activated CLL cells were significant increases in expression of CD38 (n=7, p=0.0001) and of T-cell zeta associated protein (ZAP-70) tyrosine kinase (n=14, p=0.0005). The increased expression of both these proteins in circulating peripheral blood CLL cells has been associated with poor prognosis. All six ODN* activated CLL isolates analysed by western blotting showed increased survivin expression with no constitutive expression in the controls. Drug sensitivity was studied in cells from eight patients using the MTT assay. Activated cells showed significantly greater resistance to chlorambucil (median IC50=164.4±28.18μM) compared to control cells (median IC50=93.63±14.96μM, p=0.044). Figure 1 shows representative IC50 curves. The increased resistance of the activated cells to chlorambucil may be a consequence of the upregulation of survivin. In summary, the in vitro model replicates several key features of authentic proliferating CLL cells found in bone marrow and lymph nodes. It also shows increased resistance to the conventional drug chlorambucil. This model may be of value in evaluating novel drugs and drug combinations which may be more effective in killing the proliferating population that maintain the malignant cell population in CLL. Figure Figure

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