The treatment of bone defects caused by diseases, trauma, or tumor has always been a great clinical challenge. Implantation of bone biomaterials into bone defect areas is an effective method for bone injury repair. In this study, we used three-dimensional (3D) printing technology to prepare nano-hydroxyapatite (nHA)/sodium alginate (SA)/gelatin (Gel) hydrogel scaffolds loaded with different ratios (0, 0.13, 0.26, 0.39, 0.53, and 0.79‰) of emodin (EM) (EM/nHA/SA/Gel). Scanning electron microscopy showed that the scaffolds had a smooth surface without fracture and nHA was evenly distributed on the surface. The cell proliferation and migration results showed that the 0.39‰ EM group, in particular, could significantly promote the proliferation and migration of mouse embryonic osteoblast precursor (MC3T3-E1) cells and significantly increase the mRNA expression of osteogenic differentiation-related genes (bone morphogenetic protein/BMP-2, BMP-9, osteocalcin). In addition, the 0.39‰ EM group exhibited the best effect on osteogenic differentiation-related proteins (alkaline phosphatase, Runx 2, OSX). The expression of M2 polarization-related genes (arginase-1, CD206) also significantly increased after the treatment with the 0.39‰ EM group. Micro-CT showed that in the rat skull defect model, the EM/nHA/SA/Gel scaffold group significantly promoted bone regeneration after being implanted into the skull for 30 days. Our results indicate that the EM/nHA/SA/Gel hydrogel scaffolds can not only directly promote the proliferation and differentiation of osteoblasts but also indirectly promote osteogenic differentiation by supporting M2 polarization of macrophages. EM/nHA/SA/Gel hydrogel scaffolds are potential bone tissue engineering materials for bone regeneration.
Background: Current studies still have a controversy on the effect and doses of irradiation (IR) on bone regeneration. Moreover, the mechanisms of IR to bone regeneration mainly focus on the direct effects on osteoblasts, with neglect to the role of the surrounding immune environment. Our purpose was to explore the effect of IR on osteoblasts proliferation and macrophages polarity.Results: Here in this study, we firstly established the rat cranial defects model and revealed that low-dose IR≤2 Gy gradually promoted bone regeneration, while high-dose IR>2Gy inhibited bone regeneration. The change of macrophage polarity in peripheral blood samples showed that low-dose IR≤2 Gy triggered M2 polarization of macrophages, high-dose IR>2 Gy led to M1 polarization. The cellular level also showed the similar results, mouse leukemia cells of monocyte macrophages cells (Raw264.7) exhibited M2 polarization under low-dose IR≤2 Gy, and M1 polarization under high-dose IR>2Gy. Furthermore low-dose IR≤2 Gy promoted the proliferation of osteoblasts, while high-dose IR>2 Gy exhibited the opposite result. The co-culture results showed that low-dose IR≤2 Gy not only promoted bone regeneration through osteoblasts proliferation, but also promoted bone regeneration through M2 polarization of Raw264.7 cells, while high-dose IR>2 Gy had the opposite effect.Conclusions: Our findings have revealed that low-dose IR≤2 Gy promotes bone regeneration by indirectly promoting macrophage M2 polarization and direct osteoblast proliferation, while high-dose IR>2 Gy has the opposite effect, which might offer inspirations for the related studies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.