Open Access

ARTICLE

Osmotic Loading of in Situ Chondrocytes in Their Native Environment

Rami K Korhonen^∗,†, Sang-Kuy Han^‡, Walter Herzog^‡

∗ Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Dr NW, Calgary, Alberta, T2N 1N4 Canada
† Department of Physics and Mathematics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland. Corresponding author. Tel. +358 40 3553260; Fax. +358 17 163266; E-mail: rami.korhonen@uef.fi
‡ Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, University of Calgary, 2500 University Dr NW, Calgary, Alberta, T2N 1N4 Canada

Molecular & Cellular Biomechanics 2010, 7(3), 125-134. https://doi.org/10.3970/mcb.2010.007.125

Abstract

Changes in the osmotic environment cause changes in volume of isolated cells and cells in tissue explants, and the osmotic environment becomes hypotonic in cartilage diseases such as osteoarthritis (OA). However, it is not known how cells respond to a hypotonic osmotic challenge when situated in the fully intact articular cartilage.
A confocal laser scanning microscope was used to image chondrocytes of intact rabbit patellae in an isotonic (300 mOsm) and hypotonic (172 mOsm) immersion medium. Cell volumes were calculated before and 5, 15, 60, 120 and 240 minutes after the change in saline concentration. Local tissue strains and swelling of the entire tissue were estimated from the relative movements of cells and displacements of single cells, respectively.
Cell volumes increased rapidly (≤5 minutes, p<0.05) by ∼22%, after which they remained constant for an hour (p>0.05). However, two and four hours post the hypotonic challenge, cell volumes were statistically greater (p<0.05) than those at all earlier time points, and swelling of the entire tissue continued throughout the four hour loading period.
Theresultsofourstudysuggestthatosmoticloading induced volume changes of in situ chondrocytes in their native environment occur quickly and continue for hours. Understanding the behaviour of cells in their native environment provides novel insigth into the cell mechanics in ostearthritic joints and so may help understand the onset and progression of this disease.

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