Abstract:
Background In the past decades, various synthetic bone scaffolds have been developed and applied to bone defects. However, due to poor degradation properties or osteoinductive ability, it cannot be widely used. Magnesium phosphate cement (MPC) has received much attention in recent years due to its excellent properties.
Objective To investigate the biocompatibility of injectable magnesium phosphate cement and its effect in repairing bone defects in the femural condylar.
Methods Magnesium phosphate bone cement was prepared by acid-base reaction; Mechanical strength and injectability of MPC were tested by universal testing machine and weighing method, The setting time of MPC was determined by Vica apparatus, and the material was characterized by scanning electron microscopy. The cytocompatibility of MPC was detected by CCK-8 method and live-dead staining; MPC was used to repair femoral condyle defect with diameter of 2.5 mm in rats. Experimental groups were divided into blank group, Calcium phosphate cement (CPC) group, Calcium sulfate cement (CS) group and magnesium phosphate cement group according to different implants, with 6 SD rats in each group. The specimens were taken at 4 and 8 weeks after surgery and were analyzed by Micro-CT to assess bone regeneration in the defective area; HE staining and Masson trichrome staining were performed to observe the bone regeneration in the defect area of each group.
Results An injectable magnesium phosphate self-curing cement was prepared successfully. MPC had a compressive strength of (36.25 ± 0.72)MPa, an injectability of 98.87% ± 0.29% and a setting time of (15.16 ± 0.32)min. The results of SEM showed that the hydration product MgKPO4·6H2O exhibited a lamellar shape with tight accumulation. The results of CCK-8 and live-dead staining showed that the activity of MC3T3-E1 cells in the high concentration extract of MPC group decreased slightly compared with the blank group; The results of Micro-CT scan showed that MPC, CS and CPC did not cause obvious infection, and all three showed significantly different rates of degradation. The results of histological analysis showed no significant inflammatory reaction and no necrosis of bone tissue in all groups after scaffold implantation into the femoral condyles of rats.
Conclusion MPC has good injectability, mechanical strength and biocompatibility, and shows more suitable degradable behavior during bone repair, and can be used to repair femoral condylar bone defects in SD rats.