[Cartilage tissue engineering with acellular cartilage matrix as scaffold in rabbit model].

Objective: To study how to repair the cartilage defect according to the principles of tissue engineering with acellular cartilage matrix as scaffold material.
Methods: The ear cartilage was obtained from a New Zealand white rabbit (weighing 2.4 kg )and then treated by a modified Courtman's four-step method to produce the acellular cartilage matrix. Eighteen New Zealand white rabbits (aged 6 months, weighing 2.4-2.6 kg) with no sex limit were divided into three groups. For every rabbit, two pieces of ear cartilage measured 1 cm x 1 cm were excised in each ear. Defects were repaired as follows: group A with the combined graft of acellular cartilage matrix and perichondrium, group B with acellular cartilage matrix and group C with perichondrium. Three animals in each group were killed 4 and 12 weeks postoperatively, respectively. Tissue samples obtained were analyzed with gross observation, hematoxylin-eosin stain, Safranine O-alcian blue stain and type II collagen messenger RNA in situ hybridization respectively.
Results: In gross observation, the repaired sites in groups A and B were not change meaningfully in their shape 4 weeks postoperatively; but they felt a bit of thicker and harder 12 weeks postoperatively. In group C two repaired sites formed scabs at 2 weeks and perforated at 5 weeks. In histological observation, there was a slight inflammatory reaction surrounding the acellular cartilage matrix 4 weeks after it was implanted in groups A and B. The inflammatory cells were mainly lymphocytes. The perichondrium graft in group C was collapsed in the defects in HE stain. The defect sites were negative for Safranine O-alcian blue stain and type II collagen mRNA in situ hybridization in all groups. At 12 weeks cells were found in the acellular matrix which arranged in irregular manner in group A in HE stain and was positive for Safranine O-alcian blue stain and type II collagen mRNA in site hybridization. In groups B and C, no new cell was found in HE stain and the repaired sites were negative for Safranine O-alcian blue stain and type II collagen mRNA in situ hybridization.
Conclusion: Acellular cartilage matrix is a potential scaffold material to the cartilage tissue engineering. The combined graft of acellular cartilage matrix and perichondrium can be an alterative method for the repair of the wounded cartilage.