Induction of cartilage growth in a rabbit ear model: a pilot study

Identifying the control of cartilage regeneration is important both clinically and in tissue engineering research. A rabbit ear model was used to simulate surgery and trauma to explore the effect of perichondrial stripping on underlying cartilage in vivo. Ten rabbits (20 ears) formed four groups: two controls and two experimental groups. Group 1 served as the unoperated control group and underwent no treatment. Group 2 served as the operated control group and underwent elevation of auricular skin flaps without stripping the perichondrium. Groups 3 and 4 underwent increasing degrees of surgical insult. Group 3 underwent elevation of a skin flap with stripping of the perichondrium on both sides of the cartilage. Group 4 underwent both perichondrial stripping and the insertion of a thin silicone sheet as a barrier between the denuded cartilage and the skin flaps. At 3 months, punch biopsies of the cartilage were performed in each zone of insult, creating multiple thin sections. The results were analyzed using a computerized morphometry system. Histopathological examination of the groups revealed a regenerative layer of neocartilage which showed distinct hypercellular features of regeneration. The thickness of the new layer was proportional to the degree of the insult (p<0.01). A controlled insult to the perichondrium created a regenerative layer of cartilage; it seems that this layer of neocartilage is proportional to the insult. Further studies are in progress to clarify these findings.