Proceedings of The Physiological Society
University of Manchester (2010) Proc Physiol Soc 19, PC59
Protection of articular chondrocytes against cartilage drying by synovial fluid.
B. T. McLintock1, A. K. Amin2, A. C. Hall1
1. Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom. 2. Dept. Orthopaedics & Trauma, Royal Infirmary of Edinburgh, Edinburgh, United Kingdom.
During reconstructive orthopaedic surgery, joint surfaces are often rinsed with saline which has a very different composition compared to synovial fluid which bathes the cartilage of the joint in vivo (1). It is not uncommon for articular cartilage to then be exposed to air and this can result in chondrocyte death (2). We have compared the viability of the cells within cartilage (chondrocytes) which has either been washed with saline and then allowed to dry, with drying cartilage from joints where the synovial fluid (SF) has simply been drained from the opened joint. Bovine metacarpophalangeal joints were obtained fresh from an abattoir, opened under aseptic conditions and either (a) rinsed with saline (0.9% w/v, Baxter’s Healthcare, Newbury, Berks.) or (b) drained of the SF. Joints were then allowed to dry in the laboratory in still air (21oC) and at given time points, full depth cartilage explants taken and placed in Dulbecco’s Modified Eagle’s medium (DMEM). Samples were then incubated at 37oC for 120 mins, labelled with CMFDA (5-chloromethylfluorescein diacetate; 10μM) and propidium iodide (PI; 10μM) for identification of living or dead chondrocytes by confocal scanning laser microscopy (CLSM) and viability determined (VolocityTM, Improvision Ltd). Parallel samples were also cultured (37oC) for 48hrs and then labelled, to test for progressive cell death. Initial water content (as a % of total cartilage weight) and water loss were identical between the cartilage during the two procedures (initial: 70±2%; 73±5% and after 2hrs: 52±1%; 54±1% (mean ± s.d. for n=2) for saline and SF dried joints respectively. Chondrocyte death (% of total cells) in fresh saline-washed cartilage was 0.2±0.1% and this increased after 2hrs of drying to 23±11% (mean ± s.e.m. for n=8; P<0.001; Mann-Whitney test). However in fresh SF drained cartilage, 0.1±0.05% of the cells were dead, and this was not significantly different after 2hrs (1.1±0.7%; P>0.05). There was no further change in the % of dead cells for either saline-washed and dried cartilage, or synovial fluid drained joints after 48hrs of culture. The data suggest that constituents within synovial fluid which are absent from saline, protect articular chondrocytes against the deleterious effects of drying.
Where applicable, experiments conform with Society ethical requirements