Rabbit Adipose-derived Stem Cells and tibia repair

Adipose-derived stem cells (ASCs) may represent, alone or in combination with different scaffolds, a novel and efficient approach for bone regeneration. Here, we describe how autologous rabbit ASCs (rbASCs) isolated from interscapular adipose tissue, expanded and characterized in vitro, are used to regenerate a full-thickness bone defect in the tibial crest of New Zealand rabbits. The animals have been divided in 4 groups: one group where the lesions have been treated with rbASCs seeded on hydroxyapatite-disk (rbASCs-HA), one group with only rbASCs, one with just HA, and one untreated group (just defect). The follow-up was of eight weeks. Meanwhile, rbASCs have been characterized in vitro: these progenitor cells show a homogenous high proliferation rate and a marked clonogenic ability. Moreover, rbASCs demonstrate an osteogenic potential that has been evaluated by the expression of specific bone markers such as alkaline phosphatase, collagen, osteonectin and extracellular calcified matrix deposition, both in the absence and in the presence of hydroxyapatite. Eight weeks after surgical interventions, gross appearance, X-rays, histological analyses and biomechanical tests were performed on all the animals. The macroscopic analyses of all the tibias show a satisfactory filling of the lesions without any significant difference in terms of stiffness. By X-rays, a good osteo-integration appears in both scaffold-treated groups; despite the fact that HA was not completely resorbed, cells-HA treated bones show a more efficient scaffold resorption than the other group. In addition, the scaffold-treated defects show a better bone formation compared to the control samples. In particular, the new bone, formed in the presence of rbASCs-HA, is more mature and similar to the native one showing an improvement in bone mechanical properties. These results indicate that autologous ASCs-hydroxyapatite bio-construct may be a potential treatment for the regeneration of bone defects.