Usefulness of a Nanostructured Fibrin-Agarose Bone Substitute in a Model of Severely Critical Mandible Bone Defect.

Critical defects of the mandibular bone are very difficult to manage with currently available materials and technology. In the present work, we generated acellular and cellular substitutes for human bone by tissue engineering using nanostructured fibrin-agarose biomaterials, with and without adipose-tissue-derived mesenchymal stem cells differentiated to the osteogenic lineage using inductive media. Then, these substitutes were evaluated in an immunodeficient animal model of severely critical mandibular bone damage in order to assess the potential of the bioartificial tissues to enable bone regeneration. The results showed that the use of a cellular bone substitute was associated with a morpho-functional improvement of maxillofacial structures as compared to negative controls. Analysis of the defect site showed that none of the study groups fully succeeded in generating dense bone tissue at the regeneration area. However, the use of a cellular substitute was able to improve the density of the regenerated tissue (as determined via CT radiodensity) and form isolated islands of bone and cartilage. Histologically, the regenerated bone islands were comparable to control bone for alizarin red and versican staining, and superior to control bone for toluidine blue and osteocalcin in animals grafted with the cellular substitute. Although these results are preliminary, cellular fibrin-agarose bone substitutes show preliminary signs of usefulness in this animal model of severely critical mandibular bone defect.

Usefulness of a bioengineered oral mucosa model for preventing palate bone alterations in rabbits with a mucoperiostial defect.

The use of mucoperiostial flaps during cleft palate surgery is associated with altered palatal bone growth and development. We analyzed the potential usefulness of a bioengineered oral mucosa in an in vivo model of cleft palate. First, a 4 mm palate defect was created in one side of the palate oral mucosa of 3 week-old New Zealand rabbits, and a complete autologous bioengineered oral mucosa (BOM) or acellular fibrin-agarose scaffold (AS) was implanted. No material was implanted in the negative controls (NC), and positive controls were not subjected to palatal defect (PC). Animals were allowed to grow for 6 months and the results were analyzed morphologically (palate mucosa and bone size) and histologically. Results show that palatal mucosa and bone growth and development were significantly altered in NC and AS animals, whereas BOM animals had similar results to PC and the bioengineered oral mucosa was properly integrated in the host palate. The amount and compaction of collagen fibers was similar between BOM and PC, and both groups of animals had comparable contents of proteoglycans and glycoproteins at the palate bone. No differences were found for decorin, osteocalcin and BMP2. The use of bioengineered oral mucosa substitutes is able to improve palate growth and maturation by preventing the alterations found in animals with denuded palate bone. These results support the potential clinical usefulness of BOM substitutes for the treatment of patients with cleft palate and other conditions in which palate mucosa grafts are necessary with consequent bone denudation.