31P NMR spectroscopy of developing cartilage produced from chick chondrocytes in a hollow-fiber bioreactor.

31P NMR was used to measure the concentrations and spin-lattice relaxation times of phosphorus-containing metabolites in neocartilage developing in an NMR-compatible hollow-fiber bioreactor over four weeks. Separate studies were performed for tissue developing from chondrocytes taken from the proximal and the distal sternum of the chick embryo. The metabolite ratio beta-ATP/Pi did not change significantly with development (proximal: beta-ATP/Pi = 0.38+/- 0.12 at one week, beta-ATP/Pi = 0.44+/-0.07 at four weeks, P< 0.63; distal: beta-ATP/Pi = 0.39+/-0.05 at one week, beta-ATP/Pi = 0.66+/- 0.26 at four weeks, P<0.28). ATP spin-lattice relaxation times were found to be comparable to those in muscle and brain tissue (proximal: T(1)(beta-ATP) = 0.5+/-0.06 sec at one week, T(1)(beta-ATP) = 0.4+/- 0.01 sec at four weeks; distal: T(1)(beta-ATP) = 0.3+/-0.12 sec at one week, T(1)(beta-ATP) = 0.4+/-0.04 sec at four weeks). A large increase in the spin-lattice relaxation time of inorganic phosphate, from 1.2+/-0.13 sec to 3.8+/-0.04 sec (P<0.0001) over four weeks of growth, was observed in tissue developing from chondrocytes harvested from the proximal sternum. No comparable increase in T(1)(Pi) was found in tissue developing from chondrocytes harvested from the distal portion of the sternum, which ossifies later in vivo.