"Development and Application of a 3-D Perfusion Bioreactor Cell Culture System for Bone Tissue Engineering"

Blaise Porter `98

Tissue Growth Technologies
Minnetonka, Minnesota

With 600,000 bone fractures, which require surgery each year, the need for improved clinical strategies to restore function to damaged or degenerated bone is well recognized. Tissue engineering strategies that combine porous biomaterials with cells capable of producing bone have shown promise as effective bone graft substitutes in pre-clinical animal models. However, attempts to culture bone tissue-engineering implants thicker than 1mm /in vitro /often result in a shell of live cells and mineralized matrix surrounding a core of dead tissue. Obviously a 1 mm thick implant will not heal any animal larger than a baby mouse, therefore, to address this size limitation, we developed a bioreactor system, which employs a pump to actively force (perfuse) cell culture media through an implant material that is populated with bone cells. Using that system, we found a140-fold increase in mineral/bone volume within 3 mm thick implants compared with implants that were grown in static culture conditions. Just like exercise makes your muscles stronger, physically stimulating bone results in increased bone mass and strength. Therefore, we compared the effect of increasing the media flow rate for short periods of time with continuous perfusion as well as various control culture conditions in an attempt to improve bone deposition within the implant. Intermittent elevated perfusion and dynamic culture in an orbital rocker plate produced the greatest amount of mineral within 9 mm long implants compared to low and high continuous flow cases. These results show promise towards developing a future clinically applicable method for repairing injuries involving significant bone loss.