Revascularizing effect of basic fibroblast growth factor and partially deproteinised bone on femoral head defects in rabbits / 中国组织工程研究

ABSTRACT

BACKGROUND:The treatment of avascular necrosis of femoral head remains a clinical challenge. However, recent study shows that basic fibroblast growth factor (Bfgf) is an effective angiogenic growth factor. We suppose that Bfgf has the potential in treating avascular necrosis of femoral head through revascularizing effect and steogenesis.OBJECTIVE: To develop a rabbit model that simulates the clinical situation with trapdoor bone rafting and evaluate the revascularizing effect in the repair of femoral head defect with Bfgf/partially deproteinised bone (PDPB).DESIGN: A completely randomized controlled trial.SETTING: Animal Experimental Center of Kunming Medical College.MATERIALS The experiment was conducted in the Animal Experimental Center of Kunming Medical College between July 2002 and July 2003.Totally 27 adult male healthy New Zealand rabbits, weighing 2.2 to 2.8 kg,were recruited and randomly divided into Bfgf/composite PDPB group,single PDPB group, and blank control group with 9 rabbits in each group.INTERVENTIONS: ① Preparation of Bfgf/PDPB containing Bfgf 10 ng/mm3. ② Establishment and repair of femoral head defect modelTotally 27 rabbits were chosen. Bone defect model was stablished by opening a trapdoor between femoral head and femoral neck. Bfgf/PDPB was implanted in composite group; single PDPB was implanted in PDPB group; no implants were given in blank control group. The rabbits were killed after injection through blood vessels with prepared Chinese ink 2, 4and 8 weeks after operation, and then the femoral head of each rabbit was taken out as specimen.MAIN OUTCOME MEASURES: ① Histological examination and blood vessel counting. ② Image analysis of microvessel area.RESULTS: Twenty-seven rabbits all entered the result analysis. ① Histological examination and vessel count of femoral head specimens in rabbits8 weeks after operation, composite bone group implants were replaced with bone tissues and medullary cavity of bone formed. A lot of medullary vessels were present. DPB group implants were enwrapped by bonelike tissues and most of them were absorbed. Blank control group the area of femoral head defect was filled with fibrous tissues. New bonelike tissues and scattered chondrocyte island appeared in the adjacent connective tissues of defect area, with a small number of blood vessels. Microvessel count at week 2 in composite group was significantly higher than that in PDPB group and blank control group [(31.833±7.914) vs (22.917±2.079)and (11.250±4.220) (number of blood vessel/field), P ＜ 0.01, P ＜ 0.05].The number of microvessels at weeks 4 and 8 in composite bone group and DPB group was significantly greater than that in blank control group. ②Image analysis of microvessel area The transparent samples of 20 μm thick were observed under the optical microscope 2, 4 and 8 weeks after operation, there were many vessels woven into nets. Many vessels woven into nets were also found in PDPB group; there were scattered vessels in blank control group.CONCLUSION: Bfgf has the revascularizing effect on the repair of femoral head defect, and has the potential and advantages in treating avascular necrosis of femoral head.