Molded vascularized neo-ossicle formation in silicone chambers.

Vascularized bone grafts generally achieve their aims but are not used frequently owing to donor site morbidity and limited supply. To bioengineer an alternate vascularized bone graft, we developed a novel silicone bone reactor capable of producing vascularized neo-ossicles when appropriate osteoprecursor elements are included in the implanted chambers. Requirements for ossicle production were assessed in the model, including osteoprogenitor cells (donor bone marrow), osteoinductive signals (rhBMP2 or demineralized bone matrix), and osteoconductive matrix (Collagraft). Ossicle production required patency of the vascular pedicle, and for samples not containing cancellous isograft, donor marrow viability and an osteoinductive signal. Ossicles were produced without the need for an implanted osteoinductive matrix. Bone production and maturation time course were similar in chambers containing cancellous isograft, marrow/rhBMP2, and marrow/demineralized bone matrix. The demineralized bone matrix group had delayed early bone production, and the rhBMP2 group had lower final bone area. All groups had central osteolysis in the vascularized neo-ossicles. We believe the approach is promising for selected applications.