Effect of Matrix Elasticity on the Maintenance of the Chondrogenic Phenotype

Abstract

The aim of this study was to examine the influence of matrix elasticity on the maintenance of the chondrogenic phenotype of chondrocytes cultured in monolayer. We used a two-dimensional culturing system in which polyacrylamide gels with different concentrations of bis-acrylamide were coated with collagen type I. Matrices with a Young's modulus of 4, 10, 40, and 100 kPa were produced, as determined by atomic force microscopy. Porcine chondrocytes were cultivated on these matrices at a low density for 7 days. The proliferation of cells was analyzed by 5-Bromo-2'-deoxy-uridine incorporation. Maintenance of the chondrogenic phenotype was analyzed by measuring collagen type I, type II, and aggrecan gene expression, immunofluorescence staining for collagen type II, and phalloidin staining for actin filaments. Cellular proliferation and actin organization were decreased on matrices of 4 kPa compared with stiffer substrates. The differentiated phenotype of the chondrocytes grown on matrices of 4 kPa was stabilized, indicated by higher collagen type II and aggrecan, and lower collagen type I expression. These findings indicate that chondrocytes sense the elasticity of the matrix and might be used for the design of scaffolds with mechanical properties specifically tailored to support the chondrogenic phenotype in tissue engineering applications.

Cells Behave Distinctly Within Sponges and Hydrogels Due to Differences of Internal Structure

“…The strong expression of collagen type I was detected in chondrocytes residing in the sponges, showing signs of dedifferentiation. Enhanced cell proliferation in the sponges further hinted at de-differentiation of the chondrocytes in the sponges, as fully differentiated chondrocytes were known to undergo little proliferation, 29 a phenomenon that is also observed in our chondrocytes in the hydrogels. Scaffold structure may impact nutrient diffusion, which might affect cell proliferation, as sponges provided larger interconnected pores while hydrogels had less porous structure with a smaller pore size.…”

Pore orientation mediated control of mechanical behavior of scaffolds and its application in cartilage-mimetic scaffold design

“…Since in the native tissue, chondrocytes sense the mechanical properties of pericellular matrix, therefore, this soft scaffold may mechanically simulate the immediate physiologic surroundings of chondrocytes. Further, it has also been demonstrated that soft (4 kPa) scaffolds facilitate chondrogenesis, whereas stiffer ( Z40 kPa) scaffolds favor bone formation (Vickers et al, 2006;Zhong et al, 2013;Schuh et al, 2010). Therefore, the bulk moduli of the fabricated multizonal scaffolds were in the range desirable for cartilage tissue engineering.…”

Mesenchymal Stem Cell and Chondrocyte Fates in a Multishear Microdevice Are Regulated by Yes-Associated Protein

“…In contrast, rounded morphologies, soft substrates, and a lack of extrinsic mechanical force contribute to adipogenesis [2,12]. Similarly, chondrocytes with a rounded shape or exposed to soft substrates can maintain their phenotype; otherwise, these cells are likely to dedifferentiate [13,14].…”