UC San Diego

Due to the limited ability for self-repair of articular cartilage (AC), many young and old patients experience discomfort and pain, significantly affecting their quality of life. Emerging treatments with tissue engineered cartilage are limited in large part by the inability to rapidly create and test new biomimetic tissue designs, with composition and function approaching normal tissue. Classical tissue engineering methods require substantial time for formation due to the time for cells to produce sufficient quantities of matrix A newly designed bioreactor was tested for its ability to markedly increase the density of hydrogel solutions exuding fluid either by direct compaction with an applied constant pressure or permeation compaction with an applied constant fluid flow. Both methods resulted in a hydrogel that appeared much smaller and more opaque, with a final shape determined by that of the bioreactor walls or inserted spacers. The appearance was consistent with increased density based on compositional analysis, and retention of a large portion of the matrix component of the hydrogel. In addition, compressive and tensile load-bearing were improved in association with increased density. Relatively slow compaction by permeation resulted in mostly viable chondrocytes or mesenchymal stem cells, whereas relatively fast compaction by compression resulted in low cell viability. These studies demonstrate the potential for a new technology to rapidly create dense hydrogel materials of targeted geometry and density.