Alteration of the fibrocartilaginous nature of scaffoldless constructs formed from leporine meniscus cells and chondrocytes through manipulation of culture and processing conditions

Abstract

Articular cartilage and the menisci of the knee joint lack intrinsic repair capacity; thus, injuries to these tissues result in eventual osteoarthrotic changes to the joint. Tissue engineering offers the potential to replace damaged cartilage and mitigate long-term debilitating changes to the joint. In an attempt to enhance the ability of adult articular chondrocytes (ACs) and meniscus cells (MCs) to produce robust scaffoldless neocartilage, the effects of passage number, cryopreservation, and redifferentiation prior to construct formation were studied. By increasing passage number, smaller donor biopsies could be used to generate sufficient cells for tissue engineering and, in this study, no detrimental effects were observed when employing passage-4 versus passage-3 cells. Cryopreservation of cells would enable the generation of a cell bank thus reducing lead time and enhancing consistency of cell-based therapies. Interestingly, cryopreservation was shown to enhance the biomechanical properties of the resultant self-assembled constructs. With regard to redifferentiation prior to construct formation, aggregate redifferentiation was shown to enhance the biochemical and biomechanical properties of self-assembled constructs. By increasing passaging number, cryopreserving cells, and applying aggregate redifferentiation prior to neotissue formation, the utility of ACs and MCs in tissue engineering can be enhanced.

Figure 1

Gross Morphology. Representative images of constructs from each of the 24 experimental groups and 2 primary cells controls. The small bar in the lower right is equal to 3mm.

Figure 2

Acellular and Aproteinaceous Central Region. Morphological images and picrosirius red staining of bisected constructs taken illustrate the AACR and indicate that cryopreservation and aggregate redifferentiation reduced the size of the AACR. Scale bar in lower left is equal to 1mm.

Figure 3

Biochemical Properties. (A) Collagen per WW. (B) GAG/WW. Significant differences (p<0.05) exist between groups that do not contain the same letter.

Figure 4

Biomechanical Properties. (A) Compressive relaxation modulus. (B) Compressive instantaneous modulus. (C) Tensile Young’s modulus. Significant differences (p<0.05) exist between groups that do not contain the same letter.