[Joint resurfacing using allograft chondrocytes embedded in alginate gel].

Objective: To explore the feasibility of repairing the articular cartilage with allo-articular chondrocytes embedded in alginate gel.

Methods: Allo-articular chondrocytes were isolated from three adult New zealand rabbits. The cells were cultured in DMEM/F-12 supplemented with 20% fetal bovine serum (FBS). Chondrocytes of 2nd - 3rd passage were harvested and were diluted to 5.0 x 10(7) cells/ml with 1.2% alginate. Then alginate gel was formed by 102 mM CaCl(2). The gels were cultured subsequently for 1 week and then transferred to the full-thickness defects in the femoral condyles of adult rabbits. In control group the defects were left untreated. The animals were sacrificed in the 3rd and 6th month after operation respectively. The specimens were decalcified with 50% formic acid. The histologic sections were stained with safranin O-fast green, hematoxylin-eosin (H&E) and picric acid-Sirius red and immunohisto-stained for type II collagen and aggrecan. The repairing efficiency was evaluated according to Wakitani scoring.

Result: In the experiment group all 8 defects acquired repair, 7/8 were repaired with mature hyaline cartilage tissue, and 1/8 was with fibrocartilage tissue for less cell-gel inputted. The thick of repaired tissues were closed to the normal and the tissue integrated smoothly with cartilage around the defects. Safranin O staining of the matrix acted in accordance with the normal and immunostaining for type II collagen and aggrecan showed positive. Picric acid-Sirius red staining showed that the chondrocytes lined in lines and the collagen aligned like Gothic architecture structure by polarization microscopy. There was no evidence of residue of alginate and inflammation in 3rd month specimens and no obvious deterioration at 6th month. But in control group, only a small amount of fibrous, fibrocartilage, or hyaline-like tissue was seen on the surface of the defects. Wakitani scoring showed 1.75 points for the experiment group and 7.65 for the control group.

Conclusion: It is a promising way to repair the articular cartilage with homogeneous articular chondrocytes embedded in alginate gel.