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．