>> Research Projects >> Cartilage Tissue Engineering

1. Engineering cartilage using stem cell derived chondrocytes and elastic and bioactive hydrogels

Degeneration of the joint cartilage often results in joint pain, which is a major cause of disability in middle-aged and older people. The primary causes of cartilage degeneration are osteoarthritis and trauma. As many as 36 million Americans suffer from some form of arthritis and cartilage damage from sports injury is also common. Since cartilage shows very little tendency for self-repair, many techniques are explored to repair or regenerate lost cartilage. However, there has been little success and native cartilage tissue cannot be fully replaced by any engineered tissue graft developed to date. Normal joint cartilage with elastic hydrogel nature provides stable movement and support of joints and is responding to the physiological compression loading. Toward developing a tissue that close to the real joint cartilage in terms of histological and biomechanical properties, three major building blocks in cartilage tissue engineering are developed in Dr. Wen's group: 1) a light-curable, highly elastic, porous, bioactive and biodegradable polyurethane based hydrogel scaffold mimicking the mechanical properties of native hyaline cartilage; 2) stem cell derived chondrocytes; and 3) a mini-bioreactor that capable of generating physiological dynamic compression force on the cell-scaffold construct to accelerate the tissue engineering process. The picture below shows stem cell derived chondrocytes seeded in light curable hydrogel and secreted significant amount of cartilage extracellular matrix at three weeks when compression force was applied.

Figure: Stem cell derived chondrocytes cultured in porous light-curable elastic hydrogels. (A) and (B) show the cell-gel construct cultured in dynamic compressive force bioreactor. Cells are exhibit rounded, more natural morphology. (C) and (D) show cells in static culture and cells are more spreaded pattern, which is not the same as in native cartilage tissue. In addition,
The amount of aggrecan secretion (red) in compression bioreactor (B) is more than static condition (D).

In addition to the polyurethane based hydrogels mentioned above, elastic hydrogels modified from nature biomaterials, such as hyaluronic acid (hyaluronan), chitosan, collagen, are also developed for cartilage tissue engineering process.

2. Genetically engineering human stem cells for cartilage repair

Inflammatory response in joint is one major cause of osteoarthritis, especially rheumatoid arthritis. The approach is used in this study is to genetically engineer stem cell derived chondrocyte to secret bioactive factors, so that the inflammation can be controlled and new cartilage tissue can be regenerated in situ.