Non-invasive characterization of the osteogenic differentiation of hMSCs in 3D by impedance spectroscopy

Considering the fact that human mesenchymal stem cells (hMSCs) replicate and differentiate multipotently, the provide a cell source for tissue engineering and cell-based test systems. For these applications well characterized in vitro models are required as well as the possibly to observe non-invasively cellular processes e.g. differentiation or necroses of these tissue models. Within this investigation non-invasive impedance spectroscopy, was used for characterization of the osteogenic development of hMSC in scaffold-free aggregates (spheroids) as an in vitro models for osteogenesis. The osteogenic differentiation of hMSCs induced specific morphological changes which should reflect in changes of the electrical properties of the cells. The recorded impedance spectra of osteogenic treated spheroids show a significant increase in magnitude of impedance compared to controls as well as a characteristic decrease in phase of impedance. Correlated data of histological investig ations showed expression of collagenous extra cellular matrix (ECM) and its mineralization after osteogenic induction. From these findings we conclude that impedance spectroscopy is an appropriate method for non-invasive characterization of hMSCs osteogenic development, which is relevant for quality control of cell-based implants and cell-based test systems for drug development.