Potential use of craniosynostotic osteoprogenitors and bioactive scaffolds for bone engineering.

The cranial bone has a very limited regenerative capability. Patients with craniosynostosis (the premature fusion of cranial sutures, leading to skull abnormalities) often require extensive craniofacial reconstruction and repeated surgery. The possibility of grafting autologous osteoprogenitor cells seeded on bioabsorbable matrices is of great potential for inducing regeneration of craniofacial structure and protecting the brain from external insult. To this purpose we have studied the behaviour of normal and craniosynostotic mouse osteoblast cell lines, and of human primary osteoprogenitors from craniosynostotic patients. We have monitored their ability to grow and differentiate on plastic and on a scaffold composed of bioactive glass and bioabsorbable polymer by live fluorescent labelling and expression of bone differentiation markers. Cells from syndromic patients display a behaviour very similar to that observed in the stable mouse cell line we generated by introducing the human FGFR2-C278F, a mutation found in certain craniosynostosis, into MC3T3 osteblastic cells, indicating that the mutated cell line is a valuable model for studying the cellular response of human craniosynostotic osteoblasts. Both normal and mutated calvarial osteoprogenitors can attach to the bioactive scaffold, although mutated cells display adhesion defects when cultured on plastic. Furthermore, analysis of bone differentiation markers in human osteoblasts shows that the composite mesh, unlike PLGA(80) plates, supports bone differentiation. The ability of the mesh to support homing and differentiation in both normal and mutant osteoprogenitors is important, in view of further developing autologous biohybrids to repair cranial bone deficits also in craniosynostotic patients undergoing extensive reconstructive surgery.