Bone defect repair with tissue-engineered cartilage.

We tested the efficacy of a new approach for the tissue-engineered growth of cartilage developed in our laboratory in repairing surgically created bone defects in the craniums of rats. Large cranial defects were created bilaterally in the frontoparietotemporal bones of athymic nude rats (n = 10). There was gross evidence of new cartilage in 8 of 10 experimental defects that had been filled with a synthetic biocompatible, biodegradable polymer template that had been seeded in vitro with freshly isolated chondrocytes. The control defects, filled with either nothing at all or a polymer template without chondrocytes, showed no evidence of cartilaginous repair (0 of 10). Statistical analysis using McNemar's test with pooled samples showed significant differences between the two groups (p < 0.05). Prior reports concerning the biologic repair of bony defects involved stimulation of adjacent mesenchymal tissue and resulted in ingrowth of new bone. To our knowledge, this is the first report of structural cartilaginous repair of a bony defect with matrix secreted by implanted chondrocytes.