Periosteal neochondrogenesis for biologically resurfacing joints: its cellular origin

The purpose of this study was to determine if the hyaline-like cartilage produced in major full-thickness defects of a joint surface, treated by a free periosteal graft and subjected to continuous passive motion (CPM), originated exclusively from the progenitor cells of the cambium of the graft. Free periosteal grafts were raised from the tibia of both hind legs of eight male New Zealand rabbits and transplanted into full-thickness defects across the entire width of the patellar groove of 15 female rabbits. Postoperatively, CPM was instituted and the animals were sacrificed after 3 weeks. Cells from the regenerated tissue were grown from tissue explants and their karyotypes determined. In 33% of the rabbits, all cells contained a Y (male) chromosome, indicating that regenerated tissue originated exclusively from the progenitor cell of the periosteal graft. Karyotypes of the cells from the other 67% were mosaics (both female and male); thus, their cellular origin was from both the periosteal allograft and the pluripotential mesenchymal cells in the subchondral tissues.