Mineralised Collagen Scaffolds Loaded with Stromal Cell-derived Factor-1 Improve Mandibular Bone Regeneration

Objective: To create an in situ matrix environment conducive to stem cells from host bone marrow to promote bone regeneration. Methods: Three-dimensional porous, mineralised collagen (MC) scaffolds were prepared using a freeze-drying process. The microstructure of scaffolds was observed by field emission scanning electron microscopy. The Bose BioDynamic test system was applied to examine their mechanical properties in wet conditions. The effect of scaffolds loaded with stromal cellderived factor-1α (SDF-1α) on migration of stem cells was assessed using a 24-well transwell system. SDF-1α-loaded scaffolds were implanted in the critical size defect in rats and histological staining was used to evaluate the new bone formation. Results: Mechanical testing showed that the MC scaffold featured an increased Young's modulus compared with the pure collagen (Col) scaffold in wet conditions. In addition, the MC scaffold loaded with SDF-1α chemokine improved bone marrow stromal cells' migration. When implanted in mandibular bone defects with 5 mm diameter, the MC scaffolds containing SDF-1α significantly improved the formation of new bone and blood capillaries within the scaffolds, compared with the SDF-1α-loaded Col scaffolds and the control group. Conclusion: The mineralised collagen scaffolds loaded with SDF-1α, which creates a matrix environment conducive to stem cell migration, can be exploited to improve bone self-repair as an alternative to contemporary cell seeding approaches. Keywords: mineralised collagen, scaffold, stromal cell-derived factor-1, mandibular bone, regeneration