Evaluation of modulus of polycaprolactone fused deposition modeling 3D printed tissue scaffolds

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Damage to the articular surface of the knee is a fairly common injury. In one study of 31,516 knee arthroscopies 61% of the patients featured chondral lesions. In a review of 931 athletes, 225 were found to have full thickness chondral defects. Many surgical techniques, osteochondral plugs, marrow stimulation techniques, and cell transplantation, have been developed in an effort to repair chondral lesions but fall short of adequate repair in one way or another. Tissue Engineering seeks to solve the complex problem of repairing the highly specialized articular cartilage, typically through the use of tissue scaffolds. Such tissue scaffolds are typically made from bio inert or bio compatible materials which provide a support structure on which the desired cells can grow and expand. In this study scaffolds were printed using polycaprolactone with a molecular weight ranging from 55,000 to 150,000 in an effort to determine the effect of molecular weight on the modulus of the printed scaffold. Scaffolds were printed using a hobbyist level printer with filament produced on a custom designed machine capable of using different molecular weight materials. In an effort to mirror the biphasic nature of articular cartilage the scaffolds were printed using varying layer height to control pore size. Results showed that an increasing molecular weight resulted in an increasing modulus of the scaffold as well as an increasing yield stress. Work remains to better capture the long term durability of the tested scaffolds as well as optimization of pore size for the desired cells.