In vivo functions of cartilage tissues formed from spheroid-scaffold complexes
To confirm the in vivo function of the cartilage formed from the spheroid-scaffold complexes, the cartilage was transplanted into immunosuppressed female rat models of cartilage damage at the hindlimb knee. Immunosuppression was induced in the rats by injecting a combination of busulfan and cyclophosphamide, then the injury was produced in the rat models by subchondral drilling of the hind limb knee using a drill with a 2 mm diameter needle after the skin was opened at the joint.
Rats were anesthetized during the procedure. The institutional ethical committee about animal usage and care approved all procedures (No. 10 Laboratory of Animal Usage and Care /SCI). After drilling, the cartilage was placed in the hole, then the skin was closed, and the wound was treated and monitored for 12 wk.
The animals were maintained at the Laboratory of Animal Usage and Care in the isolated cage at 21 ± 2°C and 60 ± 5% relative humidity with full ventilation under a 12 h light/dark cycle (7 a.m.-7 p.m.), and they had access to food and water ad libitum.
After 12 wk, the rats were killed, and the joints were collected to evaluate the phenotype of the cartilage at the transplantation sites using safranin O-fast red staining.
Five female rats were used in this experiment.