Stimulatory effect on bone formation exerted by a modified chitosan.

A novel modified chitosan carrying covalently linked imidazole groups (average molecular weight 700,000, degree of substitution 0.28, degree of acetylation 0.08) was used to stimulate bone formation in an animal model. Lesions (7 mm diameter) were surgically made in the femoral condyle of sheep and treated with the modified chitosan. Within 40 d after surgery, the neoformed tissue occluded the surgical hole and assumed a trabecular structure in the peripheral area of the lesion, while looking like a mineralization nodule in the central part in association with a fibrous component. In the control, no sign of osteoinduction or reparative process was observed and bone marrow was rich in adipocytes.