Osteogenic potential of cultured periosteal cells in a distracted bone gap in rabbits

Osteogenesis of cultured periosteal cells was investigated in a bone-defective gap that was created artificially by distraction in the tibia of 12-week-old rabbits. A 10-mm circumferential length of periosteum was stripped from each stump of the osteotomized tibia, and the tibia was distracted rapidly (2 mm/day), resulting in disturbance of callus formation. Periosteal-derived cells, which were isolated from the contralateral tibia, were introduced into cell culture, subcultured twice to a population of 5 x 10(7) cells, and then injected into the defective bone gap when distraction was complete. Following inoculation of the cultured cells, significant new bone formation in the bone gap was observed. The control group which did not undergo cell transplantation showed only slight new callus formation which is supposed to be formed by osteogenic cells from the bone marrow. The bone mineral content of newly formed bone between the distracted tibia was analyzed quantitatively on radiographs. Histologically, the transplanted cells initially formed a mass at the injected site and then gradually differentiated into bone tissue from the peripheral region. Bromodeoxyuridine immunohistochemical stain was utilized to investigate the localization of the transplanted cells. The present study confirms that the orthotopically implanted periosteum-derived cells facilitate osteogenesis in a bone defect created using distraction in rabbits.