Abstract: ObjectiveTo explore environmental conditions under which bone marrow stromal cells could be induced into osteogenic phenotype.MethodsRat bone marrow stromal cells were isolated and proliferated in vitro, and the 3rd passage was divided into the group A (control group), group B (cells cultured in the medium containing dexamethasone, β-glycerol disodium phosphate salt hydrate, vitamin C and active form of vitamin D₃), and group C (on the bases of group B, the cells were cultured additionally with fracture hematoma extract). On the post-induction day 5, 8, and 11, the morphological changes were observed and the osteogenic markers such as alkaline phosphotase (ALP), collagen type Ⅰ (Col Ⅰ) and osteocalcin (OCN) were assayed with immunohistochemical staining, the calcification was manifested with von Kossa staining.ResultsIn the group A, no evident osteogenic effects had been observed. In the group B, on 5th day post-induction, some bone marrow stromal cells underwent a morphological change, and mild expression of ALP and Col Ⅰ was observed but with no calcification effect. On 8th day post-induction, the ratio of morphologically changed cells increased, and the expression of ALP and Col Ⅰ increased still with no evident calcification. On 11th day post-induction, anti-OCN staining was positive and the calcium nodes were showed by von Kossa staining. The phenotype changes in the group C were similar to group B, but were more evident.ConclusionBone marrow stromal cells can be induced into osteogenic phenotype in vitro with small molecular inducers. Fracture hematoma extract can enhance this effect thus might be used as an addictive in osteogeneration.

Key words: bone marrow stromal cells, induced differentiation, fracture hematoma extraction, tissue engineering