In vitro calcification in human osteoblastic cell line derived from periosteum.

Human osteoblastic cell cultures were established from human periosteum, identified on the basis of high alkaline phosphatase activity in the confluent state. The cells in the growing state showed a fibroblastic morphology and grew to form multiple layers. The cells could spontaneously calcify, and the process was accelerated by alpha-glycerophosphate. Minerals deposited on the cells consisted exclusively of calcium and phosphorus, and matured into hydroxyapatite crystals. The calcification was stimulated by the treatment with 1 alpha,25-dihydroxy-vitamin D3. These results indicate that the osteoblastic cells have the capacity to differentiate into osteocytes and form calcified human bone tissue in vitro.