Evaluation of the Biocompatibility and Osteoconduction of the Carbon Nanotube, Chitosan and Hydroxyapatite Nanocomposite with or without Mesenchymal Stem Cells as a Scaffold for Bone Regeneration in Rats

Background: Bone substitutes have been developed to assist bone regeneration in orthopedic surgeries. Mesenchymal stem cells can be added to these biomaterials to enhance bone regeneration. This study aimed to evaluate the biocompatibility and osteoconduction of a carbon nanotube, chitosan, and hydroxyapatite nanocomposite (CNCHN) that had either been enriched or not enriched with sheep bone marrow mesenchymal stem cells (BM-MSCs) in rats. Methods: A total of sixty rats were divided into groups, and an implant with or without BM-MSCs was performed subcutaneously in 20 animals (euthanized after 7 and 30 days), comparing them to 10 control animals, and in the calvaria of 20 animals (euthanized after 20 and 60 days), comparing to with 10 control animals. Subcutaneous and calvaria histologies were performed after euthanasia. Results: The subcutaneous tissue showed that CNCHN did not prompt an exacerbated inflammatory response or signs of necrosis. The histomorphological analysis by the calvaria score of the rats showed that the control group had lower scores at 20 and 60 days for bone neoformation, relative to the CNCHN groups, which showed no significant statistical differences, suggesting that the nanocomposite assisted in the regenerative process of defects in the calvaria, but with no repair potentiation when using BM-MSCs. Conclusion: CNCHN has biocompatibility and osteoconductive potential, showing promising results in bone defects.