Hyaline cartilage engineered by chondrocytes in pellet culture: histological, immunohistochemical and ultrastructural analysis in comparison with cartilage explants

Abstract

Cartilage engineering is a strategic experimental goal for the treatment of multiple joint diseases. Based on the process of embryonic chondrogenesis, we hypothesized that cartilage could be engineered by condensing chondrocytes in pellet culture and, in the present study, examined the quality of regenerated cartilage in direct comparison with native cartilage. Chondrocytes isolated from the sterna of chick embryos were cultured in pellets (4 × 10 6 cells per pellet) for 2 weeks. Cartilage explants from the same source were cultured as controls. After 2 weeks, the regenerated cartilage from pellet culture had a disc shape and was on average 9 mm at the longest diameter. The chondrocyte phenotype was stabilized in pellet culture as shown by the synthesis of type II collagen and aggrecan, which was the same intensity as in the explant after 7 days in culture. During culture, chondrocytes also continuously synthesized type IX collagen. Type X collagen was negatively stained in both pellets and explants.Except for fibril orientation, collagen fibril diameter and density in the engineered cartilage were comparable with the native cartilage. In conclusion, hyaline cartilage engineered by chondrocytes in pellet culture, without the transformation of cell phenotypes and scaffold materials, shares similarities with native cartilage in cellular distribution, matrix composition and density, and ultrastructure.

Cell–Nanofiber-Based Cartilage Tissue Engineering Using Improved Cell Seeding, Growth Factor, and Bioreactor Technologies

“…Geometric cues via cell-nanofiber interactions are likely to play a critical role for effective cartilage regeneration in this study. In addition, the centrifugation process tightly packs chondrocytes in the CNCs, promoting a spherical morphology, which also enhances chondrocytic phenotype 26 .…”

Differentiation of Human Mesenchymal Stem Cells Toward Quality Cartilage Using Fibrinogen‐Based Nanofibers

“…Thus, our in vitro results show that the chondrogenic activity of ADSCs in most nanofi brous scaffolds signifi cantly overrides those of the pallet cultures, which are the golden standard for in vitro cartilage production. [ 34,35 ] They also suggest that Col 2 and Col 10 are promising candidates for genes that are strongly affected by nanofi bers dimensionality and organization.…”

“…[ 41 ] A number of preceding studies, including ours, were focused on mimicking the fi brous protein structure of ECM utilizing different polymer-based fi brous scaffolds. [ 42 ] Up to this point, pellet cultures-thought of as the golden standard in cartilage engineering [ 35 ] was considered to work as positive control. Nevertheless, our nanofi bers scaffolds strongly supersede the pellets in their ability to enhance chondrogenic differentiation of ADSCs thus confi rming other studies indicating increased ECM production and cartilage specifi c gene expression on polymer fi brous scaffolds, while supporting cell proliferation.…”

Growth and integration of neocartilage with native cartilage in vitro

“…Chondrocytes, which are encaged within the semi-solid extracellular matrix of cartilage, demonstrate an unstable cell phenotype when grown on monolayer culture [3,22]. Previously, we studied chondrocytes originating from the non-calcified portion of chick embryo sternum in pellet culture [28]. During culture, chondrocytes retained their phenotype and subsequently produced a hyaline cartilage.…”