Cartilage generation using alginate-encapsulated autogenous chondrocytes in rabbits

In this study, we investigated the possible use of calcium alginate as a matrix for cartilage generation with autogenous chondrocytes, and examined whether the generated cartilage could keep its original volume over time when used as an implant for filling and contour restoration in the host body. Biodegradable, biocompatible, and injectable calcium alginate impregnated with isolated autogenous chondrocytes from the auricle was injected into the gluteus muscle of 12 New Zealand White rabbits. The volume of injected calcium alginate was always 3 mL, and the density of chondrocytes was 10 x 10(6) cells per milliliter. At 4 weeks (short-term period, n = 6) and 20 weeks (long-term period, n = 6) after injection, the histologic findings and the volume of the generated cartilaginous nodules were analyzed. At the time of harvest, 10 of the 12 specimens revealed findings characteristic of natural cartilage. However, histologic examination demonstrated scanty vascular and fibrous tissue ingrowth. Many osteoid matrices, including marrow-like cells, were noted in the vicinity of the neocartilage. The approximate original volume of the injected material was maintained over 20 weeks. These results suggest that although complete cartilage replacement was not always achieved, calcium alginate-autogenous chondrocytes may represent an injectable implant that can generate new autogenous fibro-osteo-cartilaginous tissue for volume augmentation.