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 × 17 mm), 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.

Double-edged role of mechanical stimuli and underlying mechanisms in cartilage tissue engineering

“…The research demonstrated the effect of FIS stress stimulation across sources of bovine and minipig cells. In addition, when FIS stress was added to bioactive factors, advancement in mechanical and biochemical properties was evident, with increased shear modulus by 115% compared to bioactive factor-only controls ( Figure 4A ) ( Salinas et al, 2022 ). Histologically, samples treated with bioactive substances and FIS stress showed stronger Saf O staining, which is a sign that the neocartilage structures contain more glycosaminoglycans ( Figure 4B ), and similar staining intensities using H&E ( Figure 4C ).…”

“… Using bioactive factors and FIS stress to improve neocartilage (A) Exogenous TGF-1 and FIS stress may enhance ECM content in a comparable way. Further research and combination with other mechanical stimulation regimens are encouraged in the hopes of further improving the functional properties of neocartilage by studies about additional bioactive factors, such as transforming growth factor beta 1 (TGF-β1), chondroitinase ABC (C-ABC), lysyl oxidase-like 2 (LOXL2), polycystin 1/2(PC1/2), and cytochalasin D ( Salinas et al, 2022 ). (B–D) The intensity of glycosaminoglycan staining is increased when bioactive substances and FIS stress are combined.…”