The functionality and translatability of neocartilage constructs are improved with the combination of fluid-induced shear stress and bioactive factors.

Abstract

Neocartilage tissue engineering aims to address the shortcomings of current clinical treatments for articular cartilage indications. However, advancement is required toward neocartilage functionality (mechanical and biochemical properties) and translatability (construct size, gross morphology, passage number, cell source, and cell type). Using fluid-induced shear (FIS) stress, a potent mechanical stimulus, over four phases, this work investigates FIS stress' efficacy toward creating large neocartilage derived from highly passaged minipig costal chondrocytes, a species relevant to the preclinical regulatory process. In Phase I, FIS stress application timing was investigated in bovine articular chondrocytes and found to improve the aggregate modulus of neocartilage by 151% over unstimulated controls when stimulated during the maturation stage. In Phase II, FIS stress stimulation was translated from bovine articular chondrocytes to expanded minipig costal chondrocytes, yielding a 46% improvement in aggregate modulus over nonstimulated controls. In Phase III, bioactive factors were combined with FIS stress to improve the shear modulus by 115% over bioactive factor-only controls. The translatability of neocartilage was improved in Phase IV by utilizing highly passaged cells to form constructs more than 9-times larger in the area (11×17mm), yielding an improved aggregate modulus by 134% and a flat morphology compared to free-floating, bioactive factor-only controls. Overall, this study represents a significant step toward generating mechanically robust, large constructs necessary for animal studies, and eventually, human clinical studies.