Evaluation of bone regeneration with an injectable, in situ polymerizable Pluronic F127 hydrogel derivative combined with autologous mesenchymal stem cells in a goat tibia defect model.

In situ forming bone substitute materials are attractive candidates for filling irregularly shaped defects. In this study, a chemically modified form of the Pluronic® F127 hydrogel was used. Similar to the parent form, this derivative underwent a sol–gel transition in the body and additional radical curing resulted in a stable three-dimensional network gel with a controllable degradation rate. An extra cell source of autologous bone marrow-derived mesenchymal stem cells was mixed with the hydrogel to increase the ossification process, when implanted in noncritical size unicortical tibia defects. These cells were cultured and predifferentiated on two types of cell carrier systems, that is, gelatin CultiSpher-S® microcarriers and hydroxyapatite tubular carriers. Radiographic and histological evaluation revealed that bone regeneration was comparable in the defects with the bone substitute compositions and the untreated control defects at 2 and 4 weeks postimplantation and that newly formed bone originated fr...