Repair of critical bone defect in a rabbit model by autologous adipose-derived stem cells

OBJECTIVE Adipose-derived stem cells (ASCs), with their great availability and osteogenic potential may represent, alone or in combination with osteoconductive scaffold, a novel and efficient approach for bone regeneration. MATERIALS AND METHODS Rabbit ASCs were isolated from interscapular adipose tissue, expanded in vitro and used for regeneration of full-thickness bone defects in the tibial crest of New Zealand rabbits. The animals have been divided in 4 treatment groups: sham, disk of hydroxyapatite (HA), ASCs, and ASCs seeded on HA-disk. Meanwhile the ASCs have been in vitro characterized. Eight weeks after surgical interventions, gross appearance, X-ray, BMD and histological analyses were performed on all the animals of each group. RESULTS At first, each ASCs population shows a high proliferation rate, a marked clonogenic ability and osteogenic potential in the absence or in the presence of HA. The macroscopic analyses of all the tibias show a satisfactory filling of the lesion without any significant differences in term of stiffness between groups treated with or without cells. In both scaffold-treated groups, a good osteointegration was radiographically observed. Even if HA was not completely reabsorbed, ASCs-loaded HA showed a more efficient scaffold readsorption than the unloaded disks. Hystology shows a marked osteogenic ability of the scaffold-treated defects compared to the scaffold cell-free samples, and in particular, the new formed bone was more mature and similar to native bone in presence of scaffold + ASCs. CONCLUSIONS These results indicate that autologous ASCs-hydroxyapatite bio-construct is a potential treatment for the regeneration of bone defects.