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Updated: Jun 26, 2026
3D Hydrogel Scaffolds for Articular Chondrocyte Culture and Cartilage Generation
Published on: October 7, 2015
Cartilage tissue engineering using pre-aggregated human articular chondrocytes
1Department of Surgery, University Hospital, Basel, Switzerland.
Insights
Human articular chondrocytes (HAC) aggregate culture shows limited expansion but enhances chondrogenic capacity. Aggregation before scaffold seeding improves engineered cartilage graft quality.
Area of Science:
- Biomedical Engineering
- Tissue Engineering
- Cell Biology
Background:
- Articular cartilage defects require effective tissue engineering solutions.
- Optimizing chondrocyte behavior in vitro is crucial for cartilage regeneration.
Purpose of the Study:
- To assess human articular chondrocyte (HAC) proliferation in aggregates.
- To evaluate the chondrogenic potential of aggregated HAC versus monolayer cultures.
- To determine the impact of HAC aggregation on engineered cartilage tissue quality.
Main Methods:
- HAC cultured in aggregates with chondrocyte mitogens (TGFβ-1, FGF-2, PDGF-BB).
- Proliferation assessed by DNA content; differentiation by type II collagen mRNA.
- Engineered tissues formed in pellets or Hyaff-11 scaffolds and analyzed for GAG and histology.
Main Results:
- Aggregate cultures showed significant DNA increase from day 2 to 6, but limited further expansion.
- Aggregated HAC exhibited significantly higher type II collagen mRNA expression than monolayer cells.
- Tissues derived from aggregated HAC demonstrated enhanced glycosaminoglycan (GAG) content and staining.
Conclusions:
- HAC aggregate culture does not support substantial cell expansion.
- Pre-culturing HAC in aggregates enhances chondrogenic capacity and tissue quality.
- HAC aggregation is a valuable intermediate step for manufacturing engineered cartilage grafts.
Abstract:
In this study, we first aimed at determining whether human articular chondrocytes (HAC) proliferate in aggregates in the presence of strong chondrocyte mitogens. We then investigated if the aggregated cells have an enhanced chondrogenic capacity as compared to cells cultured in monolayer. HAC from four donors were cultured in tissue culture dishes either untreated or coated with 1% agarose in the presence of TGFbeta-1, FGF-2 and PDGF-BB. Proliferation and stage of differentiation were assessed by measuring respectively DNA contents and type II collagen mRNA. Expanded cells were induced to differentiate in pellets or in Hyaff-11 meshes and the formed tissues were analysed biochemically for glycosaminoglycans (GAG) and DNA, and histologically by Safranin O staining. The amount of DNA in aggregate cultures increased significantly from day 2 to day 6 (by 3.2-fold), but did not further increase with additional culture time. Expression of type II collagen mRNA was about two orders of magnitude higher in aggregated HAC as compared to monolayer expanded cells. Pellets generated by aggregated HAC were generally more intensely stained for GAG than those generated by monolayer-expanded cells. Scaffolds seeded with aggregates accumulated more GAG (1.3-fold) than scaffolds seeded with monolayer expanded HAC. In conclusion, this study showed that HAC culture in aggregates does not support a relevant degree of expansion. However, aggregation of expanded HAC prior to loading into a porous scaffold enhances the quality of the resulting tissues and could thus be introduced as an intermediate culture phase in the manufacture of engineered cartilage grafts.
