Cartilage formation in a hollow fiber bioreactor studied by proton magnetic resonance microscopy

The ideal in vitro system for investigating the regulation of cartilage for mation and maintenance would allow for three-dimensional tissue growth, a w ide range of biochemical interventions, and non-destructive evaluation. We have developed a hollow fiber bioreactor (HFBR) system which meets these cr iteria. After injection with embryonic chick sternal chondrocytes, neocarti lage is elaborated around the hollow fibers, reaching a thickness of up to a millimeter after four weeks of growth. This process was monitored over ti me with nuclear magnetic resonance (NMR) microimaging and correlative bioch emical and histologic analyses. Tissue volume and cellularity increased gre atly during development. This was accompanied by changes in magnetic resona nce properties consistent with increased macromolecular content. Further, t issue heterogeneity, observed as regional variations in cell size in histol ogic sections, was also observed in quantitative NMR images.