BIOREACTOR AND PROBE SYSTEM FOR MAGNETIC-RESONANCE MICROIMAGING AND SPECTROSCOPY OF CHONDROCYTES AND NEOCARTILAGE

We have developed a nuclear magnetic resonance (NMR)-compatible hollow fiber chondrocyte bioreactor (HFBR), permitting the noninvasive study of neocartilage under conditions optimized for cell growth and matrix expression. The system was used to investigate the properties of neoc artilage which developed from embryonic chick chondrocytes. Histologic studies performed 30 days after inoculation of the HFBR with chondroc ytes showed cartilage growth units demarcated by stromal layers surrou nding each fiber, the tissue itself was highly cellular with abundant proteoglycan content. Spin-density, spin-lattice, and spin-spin relaxa tion and magnetization transfer contrast images revealed heterogeneous tissue with NMR properties that correlated well with histologic data. It was found that the apparent free water content of the neocartilage was greater than that seen in mature cartilage, even in regions of re latively low cell density. The bioenergetic profile of the cells in cu lture was monitored with P-31-NMR spectroscopy, and the presence of ph osphocreatine was clearly demonstrated. Overall metabolic stability wa s confirmed between days 10 and 17 after inoculation. A significant de crease in intracellular pH with time was observed during early develop ment of the chondrocyte system. (C) 1997 John Wiley & Sons, Inc.