Non-destructive label-free continuous monitoring of in vitro chondrogenesis via electrical conductivity and its anisotropy

ABSTRACT Non‐destructive label‐free continuous monitoring of in vitro tissue culture is an unmet demand in tissue engineering. Noting that different compositions of cartilage lead to different electrical tissue properties, we propose a new method to measure the electrical conductivity and its anisotropy during in vitro chondrogenesis. We used a conductivity tensor probe with 17 electrodes and a bio‐impedance spectroscopy (BIS) device to measure the conductivity values and the anisotropy ratios at the bottom and top surfaces of the tissue samples during the culture period of 6 weeks. Clearly distinguishing glycosaminoglycans (GAGs), collagen, and also various mixtures of them, the measured conductivity value and the estimated tissue anisotropy provide diagnostic information of the depth‐dependent tissue structure and compositions. Continuously monitoring the individual tissue during the entire chondrogenesis process without any adverse effect, the proposed method may significantly increase the productivity of cartilage tissue engineering. Biotechnol. Bioeng. 2015;112: 422–427. © 2014 Wiley Periodicals, Inc. Bioimpedance spectropscopy (BIS) was employed for tissue characterization during in vitro chondrogenesis. A higher level of vitamin C (0.6 mM) produced well‐constructed cartilage tissue in vitro compared with the control case (0.3 mM). The BIS‐based method could successfully detect the difference in the tissue formations. In vitro chondrogenesis can be non‐destructively monitored by using the proposed method, which may improve the productivity in cartilage tissue engineering.