Expression and significance of osteogenic genes on porous tantalum-bone interface during osteogenesis / 中国组织工程研究

ABSTRACT

BACKGROUND:Previous studies have shown that home-made porous tantalum has non-toxicity and good biocompatibility, and can promote osteogenesis. Herein, we explore the mechanisms of tantalum-bone interface osseointegration.OBJECTIVE:To observe the morphological characteristics and expressions of integrin β1 and fibronectin on the interface between porous tantalum and bone tissues after implantation into the right rabbit femur, and to evaluate the biological mechanisms of tantalum-bone interface osseointegration.METHODS: Animal models of bilateral femoral condyle defects were made in Japanese big ear rabbits. Porous tantalum rod and allogeneic bone were respectively implanted into the left (experimental group) and right (control group) femur of rabbits. The animal specimens at the bone defect region were taken and made into paraffin sections and hard tissue sections at postoperative 2, 4, 8 weeks for morphological observation of new bone at the junction between the tantalum rod and host bone under light microscope, for osteogenic observation of the tantalum-bone interface under scanning electron microscope, and for immunohistochemical detection of integrin β1 and fibronectin expression.RESULTS AND CONCLUSION:Porous tantalum was bonded closely with the host bone. The loose and thick fibrous capsule was observed in the early stage and became thinner in the late stage shown by hematoxylin-eosin staining. The new bone was visible on tantalum-bone interface. Hard tissue slicing observation showed that the new bone was seen on the porous tantalum-bone interface, blood capillaries grew into the pores at postoperative 2 weeks and the pores were full of new bone tissues at postoperative 4 and 8 weeks. Under the scanning electron microscope, the osteoblasts appeared on the tantalum surface and in the pores at the early stage, and bone maturation and lamelar bone were seen at the late stage. The immunohistochemical results showed that the expression of integrin β1 in the experimental group was significantly lower than that in the control group at postoperative 2 weeks (P 0.05). In addition, there was a decline trend in the expression of integrin β1 and fibronectin atpostoperative 2, 4, 8 weeks. To conclude, the porous tantalum material is beneficial to enhance adhesion of osteoblasts on the surface and inside the micro-pores. Increased expression of integrin β1 and fibronectin on the tantalum-bone interface at early stage may promote early osteogenesis, while their decreased expression at bone maturing stage can promote osseointegration and bone remodeling.