Objective To investigate the effect of astragalus polysaccharides(AP) on chitosan／polylactic acid(AP／C／PLA)scaffolds and marrow stromal cells(MSCs)tissue engineering on periodontal regeneration of horizontal alveolar bone defects in dogs． Methods MSCs were isolatedfrom the bone marrow and then cultured in conditioned medium to be induced to become osteogenic．The MSCs were harvested and implanted into AP／C／PLA and C／PLA scaffolds．A horizontal alveolar bone defect(5 mm depth, 2 mm width)were produced surgically in the buccal side of the mandibular premolar 3 and 4 of 10 dogs．The defects were randomly divided into 4 groups(n=10)：Group A, root planning only(blank contro1); group B, AP／C／PLA with conditioned medium(medium contro1);group C, C／PLA with MSCs(scaffolds contro1); and group D, AP／C／PLA with MSCs(experimental group)．Eight weeks after surgery， block sections of the defects were collected for gross, histological and X-ray analysis. Results MSCs induced in vitro exhibited an osteogenic phenotype with expressingcollagen I and alkaline phosphatase． X-ray film observation showed that the bone density and height had no changes in group A; in group B, the bone density was increased to a certain extent and furcation area reached a few height, but no height was increased in interdental septum; in group C，the bone density was increased and furcation area nearly reached the native height,but interdental septum reached a few height;in group D,the bone density was increased significantly and furcation area and interdental septum reached the native height. Histological evaluation showed that there was greater tissue formation in group D than that in groups A, B and C, in which new alveolar bone, new cementum, periodontal ligament with Sharpey’s fibers, and new bone tissue was similar to native periodontal tissues. Ingroup A，B, C and D respectively, the amount of new alveolar bone regeneration was 0.83±0.30, 1.46±0.55, 2.67±0.26 and 2.90±0.41 mm; new cementum regeneration was 0.78±0.45，1.30±0.60，2.29±0.18 and 2.57±0.22 mm; the amount of connective tissue adhesion was 0.80±0.22，1.33±0.34，2.23±0.42 and 2.64±0.27 mm; all showing significant differenecs between group D and groups A, Band C (Plt;0.05)．Conclusion The technology of tissue engineering with AP／C／PLAscaffolds and induced MSCs may contribute to periodontal regeneration．
Objective To investigate the clinical effects of repairing massive bone defects in limbs by using vascularized free fibular autograft compoundingmassive bone allografts. Methods From January 2001 to December 2003, large bone defects in 19 patients (11 men and 8 women, aging from 6 to 35 years) were repaired by vascularized free fibular transplant with a monitoringflap compounding massive deep frozen bone allografts. The length of bone defects were 12 to 25 cm (16.6 cm on average), of vascularized free fibular 15 to 28 cm (18.3 cm on average), and of massive bone allografts 11 to 24 cm (16.1 cm on average). Thelocation of massive bone defects were humerus in 1 case, femur in 9 cases and tibia in 9 cases. Results After followup of 5 to 36 onths (18.2 months on average), wounds of donor and recipient sites were healed at Ⅰstage, monitoringflaps were alive, no obvious eject reaction of massive bone allografts was observed and no complications occurred in donor limbs. The radiographic evidence showed union in 15 patients 3 months and 3 patients 8 months after operation. One case of malignant synovioma of left lower femur recurred and amputation was performed 2.5 months after surgery. Internal fixation was removed in 5 patients, and complete bone unions werefound 1 year postoperatively. No massive bone allografts was absorbed or collapsed. Conclusion With strict indication, vascularized free fibular autograft compounding massive bone allografts, as an excellent method of repairing massive bone defects in limbs, can not only accelerate bone union but also activate and changer the final results of massive bone allografts from failure.
With the continuous progress of materials science and biology, the significance of biomaterials with dual characteristics of materials science and biology is keeping on increasing. Nowadays, more and more biomaterials are being used in tissue engineering, pharmaceutical engineering and regenerative medicine. In repairing bone defects caused by trauma, tumor invasion, congenital malformation and other factors, a variety of biomaterials have emerged with different characteristics, such as surface charge, surface wettability, surface composition, immune regulation and so on, leading to significant differences in repair effects. This paper mainly discusses the influence of surface charge of biomaterials on bone formation and the methods of introducing surface charge, aiming to promote bone formation by changing the charge distribution on the surface of the biomaterials to serve the clinical treatment better.