Experimental Study On Ectopic Osteogenesis Of Composite Of Tissue Engineered Nano-scaffold And Bone Marrow-originated Osteoblast

Bone defect and sejunctus bone,which are derived from trauma, infection, congenital malformation, malignant tumor, etc, are always the tough problems in the orthopedic field.The traditional restorative procedure including autogenous bone transplantation, variant bone transplantation and artificially synthetized substitutes and so on can't meet the clinical need of various kinds bone defect reconstruction due to its shortages. To obviate the need for harvesting of grafts and to avoid the failings for using biomaerials alone,a search for bone production via tissue engineering,a new emerging field in biomedicine has begun.In bone tissue engineering research,some kinds of ideal scaffolds providing three-dimensional space for cells growing and tissue formation,have to be investigated and have been the highlight one .In this study,the scaffold material of nanometer size, lysine diisocyanate-glycerol (LDIG) polymer which was obtained from a series of procedures of polymerization and supercritical anti-solvent precipitation(SAS), was an ideal biomaterial with favourable biocompatibility,osteophony and porous structure. In order to observe the osteogenesis and explore the feasibility and security of LDIG as the scaffold material for tissue-engineered bone construction,bone marrow-originated osteoblasts were seeded on the LDIG scaffold and the composite was then implanted into the subcutaneous tissue of nude mice.Methods: 1. Bone marrow cells obstained from immature New Zealand rabbits were cultured and differentiated into osteoblasts.The latter were seeded on the LDIG discs. The scaffold material in the control group was polylactic acid(PLA). Cell counting, collagen I staining, alkaline phosphatase activities(ALP) and scanning electron microscopy (SEM) were applied to test the osteoblast multiplication and osteogenesis activities.Results: Osteoblast multiplication and osteogenesis activities on the LDIG scaffold excelled those on PLA scaffold. 2.The 3rd generation bone marrow-originated osteoblasts obstained from immature New Zealand rabbits were seeded on the LDIG discs(density 1.75×10~6/ml) and the composites were then implanted into the subcutaneous back of nude mice. Meanwhile,the samples of LDIG alone were implanted as negative control group. The specimens were retrieved at 4 ,8 and 12 weeks. New bone formation was assessed by means of macroscopic observation, radiological and histologic examination.Results:After the composites of LDIG discs and osteoblasts were implanted,no and less new bone formation existed at postoperative 4 and 8 weeks, respectively. New bone formaton was obviously observed at 12 weeks.In LDIG alone group, the histologic and radiological features of all the control specimens demonstrated no new bone formation.Conclusions: 1.Lysine diisocyanate-glycerol (LDIG) polymer of nanometer size can be served as scaffold material for constructing of tissue engineering bone because of its ideal porous structure and good osteoblasts biocompatibility; 2. Osteoblats/LDIG composite present a promising prospect for bone defect reconstruction for its ectopic osteogenesis.