Long-term preservation of Bone Morphogenetic Activity in stored demineralized murine incisors.

Demineralized bone or dentine implanted intramuscularly induce endochondral bone formation. This phenomenon, termed "bone induction" is triggered by non-collagenous signal molecules, named "Bone Morphogenetic Proteins" (BMPs), released from bone or dentine. Demineralization of bone/dentine prior their implantation facilitates the release of BMPs from the extracellular matrix allowing to reach a BMP threshold level needed to initiate the process of differentiation of mesenchymal cells towards an osteogenic/chondrogenic lineage. Unprocessed, mineralized tissues usually fail to induce cartilage/bone. Isolated BMPs are commercially available, and in clinical practice are an alternative for demineralized tissues, however, in many cases demineralized bone has advantages over soluble BMPs, as it combines both bone inducing principles and mechanical properties, a feature important for bridging bone fracture and filling bone defects. Demineralized bones are an inexpensive source of bone forming agents for bone-fracture healing or filling bone defects. In this report we demonstrated that storage of lyophilized demineralized murine incisors for 30 months does not deteriorate its osteoinductive potency and colonizing induced bone by bone marrow. Lyophylized incisors, stored for 0-30 months at refrigator were implanted intramuscularly and recovered, together with surrounding tissues at various time intervals ranging 10-450 days. Bone closely associated with implant was observed in about 87% of cases, regardless the storage duration. It is concluded that storage of demineralized and lyophilized incisor matrices for at least 30 months does not change their osteoinductive potency.