Development and characterization of an in vitro fluorescently tagged 3D bone-cartilage interface model

Area of Science:

• Biomaterials Science
• Cell Biology
• Tissue Engineering

Background:

• Three-dimensional (3D) cultures are crucial for studying bone and cartilage interactions.
• Existing models often focus on pairwise cell interactions (e.g., osteoblast-osteoclast or osteoblast-chondrocyte).
• A model incorporating osteoblasts, osteoclasts, and chondrocytes is needed to mimic joint cellular interactions and study associated diseases.

Purpose of the Study:

• To develop a novel 3D bone-cartilage interface (3D-BCI) model.
• To incorporate osteoblasts, osteocytes, osteoclasts, and cartilage into a single 3D system.
• To utilize fluorescently tagged cell lines for assessing cell interactions during differentiation.

Main Methods:

• Development of fluorescently tagged mouse cell lines (MC3T3 for osteoblasts/osteocytes, Raw264.7 for osteoclasts).
• Establishment of a novel method for differentiating ATDC5 cells into cartilage spheroids.
• Integration of these components into a 3D-BCI model and assessment using Incucyte and functional analyses.

Main Results:

• Successful differentiation and integration of osteoblasts, osteocytes, osteoclasts, and cartilage were confirmed.
• Positive staining for TRAP, ALP, Alizarin red, and Alcian blue validated osteoblastogenesis, osteoclastogenesis, and cartilage formation.
• Gene expression analysis showed increased markers for osteoblasts (Alpl, Bglap, Col1A2, Runx2), cartilage (Acan, Col2A1, Plod2), and osteoclasts (Acp5, Rank, Ctsk).

Conclusions:

• A functional 3D bone-cartilage interface (3D-BCI) mouse model was successfully developed.
• The model accurately recapitulates the cellular composition and interactions found in joints.
• This 3D-BCI model provides a valuable platform for investigating joint diseases.