Abstract
Cultured chondrocytes have potential for cartilage regeneration to treat degenerative diseases. However, when explanted chondrocytes are cultured in monolayer, they are known to dedifferentiate over time, adopting a more fibroblastic phenotype. This greatly impacts both research and potential clinical applications; cell-based cartilage repair therapies require significant in vitro expansion to obtain sufficient chondrocyte numbers for reimplantation, as chondrocytes adopt a more fibroblastic phenotype causing up to 70% of patients to develop fibrocartilaginous fill. We used dielectrophoresis (DEP) to observe changes in the electrophysiological properties of primary bovine chondrocytes over time. Using a multi-conductivity approach, we demonstrate that monitoring the cytoplasmic conductivity is a reliable method of observing cell changes over 100 days in culture. Results show statistically significant changes in both membrane capacitance (
p
= 0.0039) and cytoplasm conductivity (
p
= < 0.0001) when tested at multiple conductivities. Analysis of cytoplasmic vs. medium conductivity allowed simple tracking of chondrocyte membrane potential, which exhibited transitions between three stable values of V
m
which correspond to patch-clamp-derived literature values as they transition from chondrocytes (− 13 to − 18 mV) to proliferating fibroblasts (− 32 to − 43 mV) and ultimately to non-proliferating fibroblasts (− 55 to − 71 mV), transitions occurring around days 40 and 80 respectively.