Reconstruction of orbital defects by implantation of antigen-free bovine cancellous bone scaffold combined with bone marrow mesenchymal stem cells in rats.

BACKGROUND

Tissue-engineering approach can result in significant bone regeneration. We aimed to reconstruct the segmental orbital rim defects with antigen-free bovine cancellous bone (BCB) scaffolds combined with bone marrow mesenchymal stem cells (BMSCs) in rats.

METHODS

BCB was prepared by degreasing, deproteinization and partly decalcification. BMSCs isolated from green fluorescent protein (GFP) transgenic rats were osteogenically induced and seeded onto BCB scaffolds to construct induced BMSCs/BCB composites. An 8-mm full-thickness defect on the rat inferior-orbit rim was established. Induced BMSCs/BCB composites cultured for 5 days were implanted into the orbital defects as the experimental group. Noninduced BMSCs/BCB group, BCB group and exclusive group were set. General condition, spiral CT, 3D orbital reconstruction, histological and histomorphometric analysis were performed after implantation.

RESULTS

BCB presented reticular porous structure. GFP-BMSCs adhering to BCB appeared bright green fluorescence and grew vigorously. Infection and graft dislocation were not observed. In induced BMSCs/BCB group, CT and 3D reconstruction showed perfect orbital repair situation. Histological analysis indicated BCB was mostly biodegraded; newly formed bone and complete synostosis were observed. The percentage of newly formed bone was (57.12 ± 6.28) %. In contrast, more residual BCB, less newly formed bone and nonunion were observed in the noninduced BMSCs/BCB group. Slowly absorbed BCB enwrapped by fibrous connective tissue and a small amount of new bone occurred in BCB group. Fibrous connective tissue appeared in exclusive group.

CONCLUSIONS

Antigen-free bovine cancellous bone that retains natural bone porous structure and moderate mechanical strength with elimination of antigen is the ideal carrier for mesenchymal stem cells in vitro. BCB combined with BMSCs is a promising composite for tissue engineering, and can effectively reconstruct the orbit rim defects in rats.