Synovial Membrane and Articular Cartilage

Co-culture systems-based strategies for articular cartilage tissue engineering

Cartilage engineering facilitates repair and regeneration of damaged cartilage using engineered tissue that restores the functional properties of the impaired joint. The seed cells used most frequently in tissue engineering, are chondrocytes and mesenchymal stem cells. Seed cells activity plays a key role in the regeneration of functional cartilage tissue. However, seed cells undergo undesirable changes after in vitro processing procedures, such as degeneration of cartilage cells and induced hypertrophy of mesenchymal stem cells, which hinder cartilage tissue engineering. Compared to monoculture, which does not mimic the in vivo cellular environment, co-culture technology provides a more realistic microenvironment in terms of various physical, chemical, and biological factors. Co-culture technology is used in cartilage tissue engineering to overcome obstacles related to the degeneration of seed cells, and shows promise for cartilage regeneration and repair. In this review, we focus first on existing co-culture systems for cartilage tissue engineering and related fields, and discuss the conditions and mechanisms thereof. This is followed by methods for optimizing seed cell co-culture conditions to generate functional neo-cartilage tissue, which will lead to a new era in cartilage tissue engineering.

The classic: Cartilaginous-cup arthroplasty in ununited fractures of the neck of the femur. 1948

This Classic Article is a reprint of the original work by J. R. Moore, Cartilaginous-Cup Arthroplasty in Ununited Fractures of the Neck of the Femur. An accompanying biographical sketch of J.R. Moore is available at DOI 10.1007/s11999-011-1976-x. The Classic Article is ©1948 and is reprinted with permission from The Journal of Bone and Joint Surgery from Moore JR. Cartilaginous-cup arthroplasty in ununited fractures of the neck of the femur. J Bone Joint Surg Am. 1948;30:313–330.

Hypothesis: joints can heal

Although cartilage has a limited capacity for intrinsic repair, cells extrinsic to the cartilage can provide a mechanism for repair if the proper conditions exist. The new chondroid material produced, although not histologically or biochemically identical to mature hyaline articular cartilage, can nevertheless in many circumstances permit normal joint function and prevent further joint deterioration. The evidence suggests that joint healing results from establishing a source of cells, normalizing joint pressures, and encouraging joint motion. Much of the controversy surrounding the question of whether joints can heal results from a failure to view joint function, rather than cartilage appearance, as the most important component of the healing process, and to appreciate the significant role played by mechanical factors in promoting this response.