الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Large bone defects are considered a massive challenge in the field of oral and maxillofacial surgery. Cell Therapy using bone marrow-derived mesenchymal stem cells (BM-MSCs), as an alternative technique, has effective potential for bone regeneration. Mesenchymal stem cell-derived exosomes have emerged as cell-free therapy potential bypassing the disadvantages of stem cells and conventional bone treatment. Their ability to improve bone healing quality is examined in this study.
Aim of the study: To compare histologically and histomorphometrically the bone healing rate of critical size defects in rabbit tibia between defects treated with mesenchymal stem cells and their derived exosomes versus untreated defects and unseeded scaffolds.
Materials and Methods: Critical-sized defects were prepared on the tibia of rabbits. Experimental groups were divided into 4 groups: (a) Control group; untreated rabbits left for spontaneous healing, (b) collagen sponge with MSCs and exosomes vehicle(growth media) treated group, (c) collagen sponge with MSCs treated group and (d) collagen sponge with exosomes treated group. Sacrificing of rabbits was done at 2 and 6-week intervals. Specimens were analyzed histologically and histomorphometrically.
Results: Bone defects treated with both BM-MSCs and their derived exosomes had a significantly higher healing rate than the control and the positive control groups. The stem cells group showed the highest amount of bone formation in H&E sections while the exosomes group showed the highest activity of osteoblasts under the immunohistochemical staining using osteocalcin. Both the control group and the collagen sponge group demonstrated a significant lack of bone formation under H&E with no obvious osteocalcin staining in the defect. The collagen sponge group showed the least amount of scaffold remnants compared to the other groups where the collagen sponge was used.
Conclusion: BM-MSCs and their derived exosomes are a promising tool for bone regeneration.
Keywords: Mesenchymal stem cells, Exosomes, Critical-size defect, Bone regeneration.