Dynamic observation and quantification of type I/II collagen in chondrogenesis of mesenchymal stem cells by second-order susceptibility microscopy

Second order susceptibility microscopy was used to image and characterize chondrogenesis in cultured human mesesnchymal stem cells (hMSCs). Second order susceptibility analysis shows that the second order susceptibility tensor ratios can be used to characterize type I and II collagens in living tissues and that both collagen types are produce at the onset of chondrogenesis. Time-lapse analysis shows that relative to type I collagen, type II collagen increases with time. Eventually, type II collagen content stabilizes at the composition of 70% of total collagen content. This approach can be used to continuously and non-invasively monitor the production of collagens I/II and developed into an effective quality control tool for monitoring extracellular matrix production in engineered tissues.