FIG. 6.

Persistence of the chondrocyte phenotype in vivo. HACs seeded onto collagen sponges were transfected with an INTERFERin-siRNA complex (50 nM NC) siRNA, or 50 nM COL1A1 siRNA and/or 50 nM HtrA1 siRNA). HACs were then cultured in hypoxia (3% O₂) with or without BMP-2 (50 ng/mL) until day 7. They were next implanted subcutaneously in nude mice for 28 days as described in the “Materials and Methods” section. (A) Implantation of type I collagen sponges containing HACs under the skin of nude mice (left). Sponges were harvested 28 days later (right). (B) HES staining of the constructs at 28 days after implantation in mice. (C) Immunostaining of type I and II collagens and aggrecan in the neo-cartilage constructs at 28 days after implantation in mice. Images shown are representative of the experimental results of three independent experiments. Scale bar: 100 μm.