Potential of fortified fibrin/hyaluronic acid composite gel as a cell delivery vehicle for chondrocytes.

Numerous treatment methods have been applied for use in cartilage repair, including abrasion, drilling, and microfracture. Although chondrocyte transplantation is the preferred treatment, it has some shortcomings, such as difficulty of application (large and posterior condylar regions), poor chondrocyte distribution, and potential cell leakage from the defect region. The cell delivery system of the tissue engineering technique can be used to overcome these shortcomings. We chose fibrin/hyaluronan (HA) composite gel as an effective cell delivery system to resolve these issues. Both components are derived from natural extracellular matrix. In the first trial, fortified fibrin/HA composite gels with rabbit chondrocytes were tested by implantation in nude mice. At 4 weeks, glycosaminoglycan contents in the fibrin/HA composite (0.186 +/- 0.006 mg/mg) were significantly higher than those in the presence of fibrin alone (0.153 +/- 0.017 mg/mg). As a next step, we applied the fibrin/HA composite gel to animal cartilage defects using full thickness cartilage defect rabbit models. The fibrin/HA composite gel with rabbit chondrocytes (allogenic) was implanted into the experimental group, and the control group was implanted with the fibrin/HA composite gel alone. Implanted chondrocytes with the fibrin/HA composite showed improved cartilage formation. In conclusion, the key to successful regeneration of cartilage is to provide the repair site with a sufficient supply of chondrogenic cells with a suitable delivery vehicle to ensure maximal differentiation and deposition of the proper extracellular matrix. This study suggests the feasibility of tissue-engineered cartilage formation using fibrin/HA composite gel.