Effect of Rate of Hydrostatic Pressure Depressurization on Cells in Culture

Abstract

Purpose : Changes in hydrostatic pressure, at levels as low as 10 mm Hg, have been reported to alter cell function in vitro; however, other studies found no detectable changes. We here investigate the hypothesis that the rate of depressurization, rather than elevated hydrostatic pressure itself, may be responsible for these reported changes.

Methods : Hydrostatic pressure (100 mm Hg above atmospheric pressure) was applied to bovine aortic endothelial cells (BAECs) and PC12 neuronal cells using pressurized gas for periods ranging from 3 hours to 9 days, and then either slowly (~30 minutes) or rapidly (~5 seconds) depressurized. Cell viability, apoptosis, proliferation, and F-actin distribution were assayed using imaging and flow cytometry. Cells were compared to controls maintained at atmospheric pressure (negative control) or exposed to staurosporine (positive control). Student t-tests, with a Bonferroni correction, and regression analysis were used for statistical comparisons with a significance level of 0.05.

Results : No significant differences were found in any measured variables between rapid and slowly depressurized cells that would explain differences previously reported in the literature. Moreover, we found no detectable effect of elevated hydrostatic pressure (slow depressurization) on any measured variable. Figure 1 shows typical results for measurements of cell proliferation. No significant change in cell count was observed for rapidly depressurized or slowly depressurized BAECs relative to negative controls for any initial seeding density or any time period investigated.

Conclusions : No mechanism has been proposed in any study to explain how cells that are essentially incompressible can be affected by low levels of hydrostatic pressure elevation. Our results join a growing body of literature [1-4] showing no effect of hydrostatic pressure on cellular processes.

1. Ressler, Am J Physiol Lung Cell Mol Physiol; 278: L1264, 2000.
2. Lei, IOVS; 52:6329, 2011.
3. Astafurov, Mol Vis; 20:140, 2014.
4. Osborne, PLoS One; 10 :e0115591, 2015.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Figure 1: Cell proliferation of BAECs exposed to elevated hydrostatic pressure and then rapidly or slowly depressurized, compared to negative control. (A) CyQUANT assay results after 24 hr of elevated hydrostatic pressure; (B) Cell counts (hemocytometer) as a function of days exposed to elevated hydrostatic pressure. Error bars: standard errors.