Abstract: Bone marrow Mesenchymal stem cells（BMSCs）are a group of adult stem cells that exist in bone marrow tissue and have the potential to differentiate in multiple directions. In recent 20 years, a lot of scientific researches have proved the potential of BMSCs in the treatment of diseases. However, the effects of BMSCs donor sources on cell biological properties and transplantation efficacy remain to be investigated. In order to explore the effects of ages on the proliferation and differentiation, BMSCs from newborn and young dogs were isolated and cultured by the same method, and the BMSCs from two sources were compared. The results showed that both BMSCs could form dense cell colonies after 6 days of isolation and culture, but the growth morphology of the cells was different. BMSCs of newborn puppies（BMSCs-n）was longer and more fibrous, while BMSCs of young dogs（BMSCs-Y）was spindle-shaped. The population doubling time of BMSCs-N group（31.99±0.26）h was significantly shorter than that of BMSCs-Y group（34.66±1.15） h. The results of cell scratch test showed that the healing rate of BMSCs-N group was significantly higher than that of BMSCs-Y group（（45.51±1.58）% vs.（37.62±2.45）%, P<0.05）at 9 h after injury, and that of BMSCs-N group was（72.13±0.97）% at 24 h after injury, BMSCs-Y group was（50.28±3.53）%. Compared with BMSCs-Y group, the differentiation rate of adipocytes in BMSCs-N group was higher（（34.25±0.22）% vs. （25.23±1.82）%, P<0.01）, and that of osteoblasts in BMSCs-N group was higher than that of BMSCs-Y group（（31.34±3.88）% vs. （15.54±0.65）%, P<0.01）. The mRNA expression levels of pluripotency genes in BMSCs-N group were significantly higher than those in BMSCs-Y group（P<0.05）. It was found that BMSCs-N were more proliferative and differentiated in vitro than BMSCs-Y. The results of this study may provide a reference for the cell therapy by BMSCs.

Key words: bone marrow mesenchymal stem cells, proliferation, differentiation, age, canine