Experimental study of recombinant human bone morphogenetic protein 2 modified tissue engineered bone in reconstruction of orbital fracture

Abstract

Objective To study the efficiency of tissue engineered bone modified by recombinant human bone morphogenetic protein 2 (rhBMP-2) in reconstruction of orbital fracture.Methods Tissue engineered bone was established in vitro by using antologous bone marrow stromal cells as daughter cells,degradable absorbable biomaterial PLGA as vector and rhBMP-2 as growth factor.The laboratory animals were divided into control group (implanted with PLGA/rhBMP-2) and experimental group (implanted with tissue engineered bone).Wound healing,complications,orbit appearance,CT imaging and histological changes were observed at one,three and six months later after the surgery.Results All the animals were with well healed wounds.Neither complications nor enophthalmus was observed.The 3-D CT scan showed that orbital floor defect scope was smaller [ (25.1±6.8)mm2 vs (55.3±7.7)mm2] and CT values was higher in experiment group at 3 months later than in controls.Six months later after operation,the bone defect disappeared in experimental group but still existed in the controls.Marginal absorption of implanted bone with a small number of osteoblasts penetrating along the stent into the biomaterial was noted in the experimental group as early as one month later after operation,but not in the controls.At 3 months later,the experimental group showed strips of newly formed bone growing into or encapsulating the biomaterial,intersecting with each other and grew,with greater level of biomaterial degradation as compared with controls.At 6 months later,the implanted materials in experimental group were totally absorbed,replaced by newly formed osseous tissues,or fused perfectly with.inherent bone tissue.In contrast,the implants in controls showed only partial degradation and absorbance.Conclusions The tissue engineered bone modified by human bone morphogenetic protein 2 may well conduct and induce the activity of bone formation.Good biocompatibility and total degradability indicate that the implant is efficient in reconstruction of orbital fracture defects. Key words: Bone morphogenetic proteins; Poly-lactic- co- glycolic acid; tissue engneering; bone ; Orbital fractures