Background: Mesenchymal stem cells have immense potential in applications of bone healing and regeneration. However, few studies have evaluated the therapeutic efficacy of adipose-derived stem cells (ASCs) and bone marrow stromal cells (BMSCs) in irradiated bone. The purpose of this study is to compare the ability of ASCs versus BMSCs to enhance healing outcomes in a murine model of irradiated mandibular fracture repair.
Methods: Forty-eight isogenic male Lewis rats underwent radiation therapy followed by mandibular osteotomy with intraoperative placement of either ASCs or BMSCs. Animals were killed on postoperative day 40. Mandibles were analyzed for union rate, biomechanical strength, vascularity, and mineralization. Groups were compared at P < 0.05 significance.
Results: The ASC and BMSC groups demonstrated 92% and 75% union rates. Compared with the BMSC group, the ASC group demonstrated a trending increase in maximum load ( P = 0.095) on biomechanical strength analysis and a significant increase in vessel number ( P = 0.001), vessel thickness ( P = 0.035), and vessel volume fraction ( P = 0.007) on micro-computed tomography angiography analysis. No significant differences in bone mineralization were identified on micro-computed tomography analysis.
Conclusion: This study demonstrates the superior therapeutic efficacy of ASCs over BMSCs in irradiated fracture healing as evidenced by union rate, vascular morphometry, and a trend in biomechanical strength. We posit that the robust vascular response induced by ASCs better recapitulates the sequence and synchronicity of physiologic bone healing compared with BMSCs, thereby improving the reliability of irradiated fracture repair.
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