Engineering of cartilage in recombinant human type II collagen gel in nude mouse model in vivo

Objective: Our goal was to test the recombinant human type II collagen (then) material as a gel-like scaffold for chondrocytes in a nude mouse model in vivo. Design: Isolated bovine chondrocytes (6 x 10(6)) were seeded into rhCII gels (rhCII-cell) and injected subcutaneously into the backs of nude mice. For comparison, chondrocytes (6 x 10(6)) in culture medium (Med-cell) and cell-free rhCII gels (rhCII-gel) were similarly injected (n = 24 animals, total of three injections/animal). After 6 weeks, the tissue constructs were harvested and analyzed. Results: Chondrocytes with or without rhCII-gel produced white resilient tissue, which in histological sections had chondrocytes in lacunae-like structures. Extracellular matrix stained heavily with toluidine blue stain and had strongly positive collagen type II immunostaining. The tissue did not show any evidence of vascular invasion or mineralization. The cell-free rhCII-gel constructs showed no signs of cartilage tissue formation. Cartilage tissue produced by Med-cell was thin and macroscopically uneven, while the rhCII-cell construct was smooth and rounded piece of neotissue. RhCII-cell constructs were statistically thicker than Med-cell ones. However, no statistical differences were found between the groups in terms of glycosaminoglycan (GAG) content or biomechanical properties. Conclusions: These results show that rhCII-gel provides good expansion and mechanical support for the formation of cartilage neotissue. RhCII material may allow favorable conditions in the repair of chondral lesions. (C) 2010 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.