Reparación de defectos críticos mandibulares mediante constructos en un modelo porcino

Resum

Its wellknown that critical defects are very difficult to repair by themselves. Nowdays, tissue engineered techniques appeared with the objective to help these situations. However, bone substitutes were successfully onto relatively small defects. The objective of this work is to evaluate the efficiency of a biomaterial (nanocrystalline carbonated hydroxyapatite reinforced agarose hydrogel) as a scaffold and/or construct (scaffold plus cells) for bone regeneration in critical mandibular defects. The GELPOR3D shaping method can be used to create what are described as ceramic reinforced hydrogels where the structural components maintain both their original microstructural and textural properties and thus their functionality. Using this method, nanohydroxyapatite/agarose (80/20%) scaffolds containing undifferentiated mesenchymal cells of adipose tissue (MSCAT) or osteogenic differentiated cells (O-MSCAT) were prepared. Histological (von Kossa, alkaline phosphatase) and immunohistochemical techniques with antibodies specific for RUNX2, OCT3/4, Nanog, and osteopontin were used for characterize the cells. For in vivo studies, we created (n=6) four critical mandibular defects (35 mm x 15 mm) (2 hemiarcade) on which the scaffold plus cells was implemented (total number of defects = 24). The animals were sacrificed after 6 months. The samples obtained were decalcified and processed for extracellular matrix (ECM) examination using scanning electron microscopy, micro-CT techniques, PCR and immunological staining (osteopontin, osteocalcin, RUNX-2 and Collagen I and III). Data were analyzed using statistical package version 22.0 SPSS. MicroCT analysis showed an increase of ~20% in the size of the defect without scaffolds. In contrast, when scaffolds and MSCAT or O-MSCATS constructs were implanted, we obtained a more than 50 % diminution in defect size. Furthermore, evaluation of ECM area showed a 40 % increase in bone regenerated area. In conclusion, nanohydroxyapatite/agarose scaffolds containing undifferentiated mesenchymal cells offer a promising approach for repairing critical mandibular defects.