In-vivo tissue engineering of biological joint replacements

In The Lancet today, Chang Lee and colleagues

report the successful regeneration of entire humeral condyles in rabbits after radical resection of the original structures. Regeneration was achieved by implantation of customised anatomically shaped bioscaffolds that were infused with collagen gel containing transforming growth factor β3 to stimulate chondrogenic differentiation of cells. No preprepared stem cells or other cells were added to the scaffold before implantation. Instead, the investigators relied on endogenous cell homing, local tissue response, and functional stimulation to recreate the entire articulating cartilaginous joint surfaces together with subchondral bone. Impressively, only 3–5 weeks after surgery, the rabbits were able to move almost as well as animals that had not undergone the procedure. However, this study was in rabbits, not in human beings. How then are the results relevant to clinicians?