Viscoelastic recovery time of chondrocytes from monolayer and alginate cultures

This study uses a previously reported 3D-printed variable-height flow cell to investigate the viscoelastic properties of chondrocytes from 2D monolayer and 3D alginate cultures. It was hypothesized that chondrocytes could be distinguished by phenotype associated with their culture environment using viscoelastic recovery time, owing to variation in the pericellular matrix (PCM) produced by chondrocytes from different culture methods. The PCM surrounding the chondrocytes was imaged with confocal microscopy during applied deformation and subsequent recovery. The projected cell area was fitted with a Burgers mechanical model to extract the viscoelastic recovery time. No difference between bovine and primary OA cells from monolayer cultures was observed. However, a statistically significant difference in recovery time was observed between cells from monolayer and alginate cultures in both the bovine (31 s vs. 13 s) and primary OA (34 s vs. 13 s) groups. This work shows that viscoelastic recovery time is influenced by the culture method used for chondrocytes and further demonstrates the role of the PCM as a mechanical protector of chondrocytes.