Transplanted tissue-engineered cartilage

Objective: To evaluate the feasibility of transplanting sculpted autogenous tissue-engineered cartilage (TEC) with the hope that it will retain precise 3-dimensional morphologic features after transplantation. Transplanted TEC is described in terms of the gross morphologic and histologic characteristics in contrast to pretransplanted TEC. Methods: Synthetic scaffolds of a polyglycolic acid and poly-L-lactic acid polymer, coated with chondrocytes derived from rabbit auricular cartilage in concentrations ranging from 2.7 X 10(6)/mL to 6 X 10(7)/mL, were incubated in vivo on the dorsum of a rabbit for 8 weeks and then retrieved. The resultant TEC specimens were then sculpted into defined shapes and transplanted into a different location in the same rabbit, where they were allowed to incubate for another 8 weeks. The specimens were then retrieved and compared with the TEC before transplantation according to size, weight, and histomorphometric analysis. Results: Thirteen chondrocyte-laden templates were successfully engineered to develop TEC. In each case, they were sculpted and transplanted to a different site in the same rabbit. Eight weeks after transplantation, all sculpted TEC specimens lost their original 3-dimensional morphologic features and experienced a significant decrease in mass. Histologically, the staining intensity of both hemotoxylin-eosin and safranin O was dramatically reduced following transplantation. In addition, there was a reduction in chondrocyte viability. Two consistent histologic findings were a foreign-body reaction to the synthetic polymer and ongoing cellular activity directed toward the formation of bone. Conclusions: Transplanting autogenous TEC does not allow the preservation of precise morphologic features that are needed for clinical implantation. The osteogenic progression and foreign body reaction must also be controlled.