Poor osteoinductive potential of subcutaneous bone cement-induced membranes for tissue engineered bone

Large segmental bone defects remain a challenge for reconstructive surgeons. A two-stage repair strategy may offer a potential solution. Here, we sought to evaluate the osteoinductive potential of bone cement-induced membranes in an ectopic site.

First, bone cements were inserted into the subcutaneous tissues of 16 rabbits to induce membrane formation. After 2, 4, 6 and 8 weeks, the induced membranes were harvested to assess their vascularization and osteoinductive potential. Next, bone cements were subcutaneously inserted into 12 rabbits for 4 weeks. These bone cements were then harvested from the newly formed membranes and replaced with granular porous β-TCP, with or without bone mesenchymal stem cells. New bone formation was then evaluated after 3, 6 and 9 weeks.

The highest level of blood vessel formation and bone morphogenetic protein-2 expression in the membranes were found at 4 weeks (p < 0.05). In addition, vascular endothelial growth factor concentration was highest after 2 weeks (p < 0.001), persisting until 8 weeks. However, the results showed little ectopic bone formation at these time points.

While bone cement-induced membranes appear to provide a suitable environment for bone formation, they fail to drive osteoinduction in non-osseous sites for the purposes of bone tissue engineering.