[The fate of donor bone cells in different diameter bone grafts: an experiment study]

To investigate the fate of donor bone cells in bone grafts of different diameters during repairing bone defects.

One hundred sixteen female syngeneic inbred DA rats were established as radial defect model of 3 kinds: structural bone grafting group (n = 56), morselized bone grafting group (n = 56), and blank group (without bone grafting, n = 4), to be used as receptors The ilia of 58 male inbred DA rats, as donors, were harvested and made into structural bone grafts 2 mm in diameter and morselized bone grafts 0.3 - 0.5 mm in diameter to be transplanted into the radial defects of the female receptors. One and four days, and 1, 2, 4, 6, and 8 weeks after transplantation DNA was extracted from the grafted bones and polymerase chain reaction (PCR) specific for the sex-determining region of Y-chromosome (Sry) was performed to observe the presence and relative amount of Y-chromosome originating from the bone grafts, expression of the sex-determining gene Sry in the receptors' bones and the histology of the receptors' bones.

In structural bone grafting group, the amounts of Sry-specific bands decreased in the early time and disappeared 1 week after transplantation, and re-appeared 4 weeks after transplantation with the amount increasing with the lapse of time. In morselized bone grafting group, Sry-specific bands were detected all the time but their amounts decreased with the lapse of time. At each time point, morselized bone graft provided more living osteocytes with better effect of osteogenesis in comparison with the structural bone graft.

Bone grafts of different diameters provide donor cells in repairing bone defects. Having more surviving osteocytes, morselized bone grafts may accelerate the healing pf bone defects, thus providing a new and effective method to repair bone defects and spinal fusion clinically.