Regulatory volume decrease (RVD) by isolated and in situ bovine articular chondrocytes

Abstract

Articular chondrocytes in vivo are exposed to a changing osmotic environment under both physiological (static load) and pathological (osteoarthritis) conditions. Such changes to matrix hydration could alter cell volume in situ and influence matrix metabolism. However the ability of chondrocytes to regulate their volume in the face of osmotic perturbations have not been studied in detail. We have investigated the regulatory volume decrease (RVD) capacity of bovine articular chondrocytes within, and isolated from the matrix, before and following acute hypotonic challenge. Cell volumes were determined by visualising fluorescently-labelled chondrocytes using confocal laser scanning microscopy (CLSM) at 21 degrees C. Chondrocytes in situ were grouped into superficial (SZ), mid (MZ), and deep zones (DZ). When exposed to 180mOsm or 250mOsm hypotonic challenge, cells in situ swelled rapidly (within approximately 90 sec). Chondrocytes then exhibited rapid RVD (t(1/2) approximately 8 min), with cells from all zones returning to approximately 3% of their initial volume after 20 min. There was no significant difference in the rates of RVD between chondrocytes in the three zones. Similarly, no difference in the rate of RVD was observed for an osmotic shock from 280 to 250 or 180mOsm. Chondrocytes isolated from the matrix into medium of 380mOsm and then exposed to 280mOsm showed an identical RVD response to that of in situ cells. The RVD response of in situ cells was inhibited by REV 5901. The results suggested that the signalling pathways involved in RVD remained intact after chondrocyte isolation from cartilage and thus it was likely that there was no role for cell-matrix interactions in mediating RVD.

Non‐enzymatic glycation of chondrocyte‐seeded collagen gels for cartilage tissue engineering

“…Hyperosmotic solutions affect gene expression, intracellular pH and calcium levels, cellular metabolism, as well as the physical and viscoelastic properties of chondrocytes. [41][42][43][44][45][46][47][48][49][50] Hyperosmotic stress has also recently been shown to lead to apoptotic cell death and plausible that the osmotic environment in the post-glycation processing method may be cytotoxic. 51 Figure 1.…”

Chondrocyte intracellular calcium, cytoskeletal organization, and gene expression responses to dynamic osmotic loading

“…7). The osmotic loading magnitude for the current study was chosen from that studied in the chondrocyte literature (7,13,27,50,62), in part to facilitate comparison of our novel dynamic osmotic experiments with those of static loading by other researchers. This finding demonstrates that dynamic osmotic loading has a similar stimulatory effect on chondrocytes as other applied dynamic mechanical stimuli.…”

The Effect of Hydrostatic Pressure on Three-Dimensional Chondroinduction of Human Adipose–Derived Stem Cells

“…[49][50][51] The newly proliferated cells and matrix impact the material=structure of the scaffold, nutrient availability, and waste dissipation in the partitioned cell construct. HP=medium perfusion may also be useful for improved mass transfer of necessary medium supply and waste exclusion.…”